Three point charges \[+q,-2q\] and \[+q\] are placed at points \[(x=0,y=a,z=0),\] \[(x=0,y=0,z=0)\] and \[(x=a,y=0,z=0),\] respectively. The magnitude and direction of the electric dipole moment vector of this charge assembly are: [AIPMT (S) 2007]

\[qa\] along the line joining points \[(x=0,y=0,z=0)\] and \[(x=a,y=a,z=0)\]

\[\sqrt{2}\,qa\] along \[+y\] direction

\[\sqrt{2}\,qa\] along the line joining points \[(x=0,y=0,z=0)\] and \[(x=a,y=a,z=0)\]

\[qa\] along the line joining points \[(x=0,y=0,z=0)\] and \[(x=a,y=a,z=0)\]

\[\sqrt{2}\,qa\] along \[+x\] direction

A square surface of side L m is in the plane of the paper. A uniform electric field \[\vec{E}\] (V/m), also in the plane of the paper, is limited only to the lower half of the square surface, (see figure). The electric flux in SI units associated with the surface is: [AIPMT (S) 2006]

\[E{{L}^{2}}/(2{{\varepsilon }_{0}})\]

As per this diagram a point charge +q is placed at the origin O. Work done in taking another point chargeQ from the point A [co-ordinates \[(0,\,\,a)\]] to another points [co-ordinates \[(a,\text{ }0)\]] along the straight path AB is: [AIPMT (S) 2005]

\[\left( \frac{-qQ}{4\pi {{\varepsilon }_{0}}}\frac{1}{{{a}^{2}}} \right)\sqrt{2}a\]

\[\left( \frac{qQ}{4\pi {{\varepsilon }_{0}}}\frac{1}{{{a}^{2}}} \right)\cdot \frac{a}{\sqrt{2}}\]

\[\left( \frac{qQ}{4\pi {{\varepsilon }_{0}}}\frac{1}{{{a}^{2}}} \right)\sqrt{2}a\]

Three capacitors each of capacity \[4\,\mu F\] are to be connected in such a way that the effective capacitance is \[6\,\mu F\]. This can be done by: [AIPMT 2003]

connecting two in parallel and one in series

connecting two in series and one in parallel

connecting two in parallel and one in series

connecting all of diem in series

connecting all of them in parallel

A charge q is located at the centre of a cube. The electric flux through any face is: [AIPMT 2003]

\[\frac{\pi q}{6(4\pi {{\varepsilon }_{0}})}\]

\[\frac{q}{6(4\pi {{\varepsilon }_{0}})}\]

\[\frac{2\pi q}{6(4\pi {{\varepsilon }_{0}})}\]

\[\frac{4\pi q}{6(4\pi {{\varepsilon }_{0}})}\]

An electron is moving round the nucleus of a hydrogen atom in a circular orbit of radius r. The coulomb force \[\vec{F}\] between the two is: [AIPMT 2003]

\[k\frac{{{e}^{2}}}{{{r}^{3}}}\vec{r}\]

\[-k\,\frac{{{e}^{2}}}{{{r}^{3}}}\vec{r}\]

\[k\frac{{{e}^{2}}}{{{r}^{2}}}\hat{r}\]

\[-k\frac{{{e}^{2}}}{{{r}^{3}}}\hat{r}\]

Identical charges \[(-q)\] are placed at each corners of a cube of side b, then the electrostatic potential energy of charge \[(+q)\] placed at the centre of the cube will be:

\[\frac{8\sqrt{2}{{q}^{2}}}{4\pi {{\varepsilon }_{0}}b}\]

\[-\frac{4\sqrt{2}{{q}^{2}}}{\pi {{\varepsilon }_{0}}}\]

\[\frac{8\sqrt{2}{{q}^{2}}}{\pi {{\varepsilon }_{0}}b}\]

\[-\frac{4{{q}^{2}}}{\sqrt{3}\pi {{\varepsilon }_{0}}b}\]

\[\frac{8\sqrt{2}{{q}^{2}}}{4\pi {{\varepsilon }_{0}}b}\]

A capacitor of capacity \[{{C}_{1}}\] is charged upto potential V volt and then connected in parallel to an uncharged capacitor of capacity \[{{C}_{2}}\]. The final potential difference across each capacitor will be: [AIPMT 2002]

\[\left( 1+\frac{{{C}_{2}}}{{{C}_{1}}} \right)V\]

\[\frac{{{C}_{2}}V}{{{C}_{1}}+{{C}_{2}}}\]

\[\frac{{{C}_{1}}V}{{{C}_{1}}+{{C}_{2}}}\]

\[\left( 1+\frac{{{C}_{2}}}{{{C}_{1}}} \right)V\]

\[\left( 1-\frac{{{C}_{2}}}{{{C}_{1}}} \right)V\]

Some charge is being given to a conductor then its potential is: [AIPMT 2002]

maximum somewhere between surface and centre

Torque acting on electric dipole of dipole moment \[\vec{p}\] placed in uniform electric field \[\vec{E}\] is: [AIPMT 2001]

\[\vec{p}\times \vec{E}\times \vec{p}\]

\[\frac{\vec{E}\,.\,\vec{p}}{{{p}^{2}}}\]

A charge \[q\mu C\] is placed at the centre of a cube of a side 0.1 m, then the electric flux diverging from each face of the cube is: [AIPMT 2001]

\[\frac{q\times {{10}^{-4}}}{12{{\varepsilon }_{0}}}\]

\[\frac{q\times {{10}^{-6}}}{24{{\varepsilon }_{0}}}\]

\[\frac{q\times {{10}^{-4}}}{{{\varepsilon }_{0}}}\]

\[\frac{q\times {{10}^{-6}}}{6{{\varepsilon }_{0}}}\]

\[\frac{q\times {{10}^{-4}}}{12{{\varepsilon }_{0}}}\]

In a parallel plate capacitor, the distance between the plates is d and potential difference across plates is V. Energy stored per unit volume between the plates of capacitor is: [AIPMT 2001]

\[\frac{{{Q}^{2}}}{2{{V}^{2}}}\]

\[\frac{1}{2}{{\varepsilon }_{0}}\frac{{{V}^{2}}}{{{d}^{2}}}\]

\[\frac{1}{2}\frac{{{V}^{2}}}{{{\varepsilon }_{0}}{{d}^{2}}}\]

\[\frac{1}{2}{{\varepsilon }_{0}}\frac{{{V}^{2}}}{{{d}^{2}}}\]

A point Q lies on die perpendicular bisector of an electrical dipole of dipole moment p. If the distance of Q from the dipole is r (much larger than the size of the dipole) then electric field at Q is proportional to: [AIPMT 1998]

\[{{p}^{-1}}\] and \[{{r}^{2}}\]

\[{{p}^{2}}\] and \[{{r}^{-3}}\]

A clock with a metal pendulum beating seconds keeps correct time at\[0{}^\circ C\]. If it loses 12.5 s a day at\[25{}^\circ C\], the coefficient of linear expansion of metal of pendulum is

\[\frac{1}{43200}/k{}^\circ C\]

\[\frac{1}{86400}/k{}^\circ C\]

\[\frac{1}{43200}/k{}^\circ C\]

\[\frac{1}{14400}/k{}^\circ C\]

\[\frac{1}{28800}/k{}^\circ C\]

Three discs A, B and C having radii 2m, 4m, and 6m respectively are coated with carbon black on their other surfaces. The wavelengths corresponding to maximum intensity are 300 nm, 400 nm and 500 nm, respectively. The power radiated by them are \[{{Q}_{a,\,}}{{Q}_{b,}}\,and\,{{Q}_{c}}\] respectively,

\[{{Q}_{a,\,}}={{Q}_{b,}}\,={{Q}_{c}}\]

A body cools in a surrounding which is at a constant temperature of\[{{\theta }_{0}}\]. Assume that it obeys Newton's law of cooling. Its temperature \[\theta \]is plotted against time \[t\]. Tangents are drawn to the curve at the points \[P(\theta ={{\theta }_{1}})\]and\[Q(\theta ={{\theta }_{2}})\]. These tangents meet the time axis at angles of \[{{\phi }_{2\,}}\] and \[{{\phi }_{1}}\], as shown

\[\frac{\tan {{\phi }_{1}}}{\tan {{\theta }_{2}}}=\frac{{{\theta }_{1}}}{{{\theta }_{2}}}\]

\[\frac{\tan {{\phi }_{2}}}{\tan {{\theta }_{1}}}=\frac{{{\theta }_{1}}-{{\theta }_{0}}}{{{\theta }_{2}}-{{\theta }_{0}}}\]

\[\frac{\tan {{\phi }_{2}}}{\tan {{\theta }_{1}}}=\frac{{{\theta }_{2}}-{{\theta }_{0}}}{{{\theta }_{1}}-{{\theta }_{0}}}\]

\[\frac{\tan {{\phi }_{1}}}{\tan {{\theta }_{2}}}=\frac{{{\theta }_{1}}}{{{\theta }_{2}}}\]

\[\frac{\tan {{\phi }_{1}}}{\tan {{\theta }_{2}}}=\frac{{{\theta }_{2}}}{{{\theta }_{1}}}\]

Three rods of equal length / are joined to form an equilateral triangle PQR. 0 is the mid point of R PQ. Distance OR remains same for small change in temperature. Coefficient of linear expansion for PR and RQ is same i.e. \[{{\alpha }_{2}}\] but that for PQ is \[{{\alpha }_{1}}\].Then

\[{{\alpha }_{2}}=3{{\alpha }_{1}}\]

\[{{\alpha }_{2}}=4{{\alpha }_{1}}\]

\[{{\alpha }_{1}}=3{{\alpha }_{2}}\]

\[{{\alpha }_{1}}=4{{\alpha }_{2}}\]

A solid copper sphere (density \[\rho \] and specific heat capacity c) of radius \[r\] at an initial temperature 200 K is suspended inside a chamber whose walls are at almost 0 K. The time required (in \[\mu s\]) for the temperature of the sphere to drop to 100 K is

\[\frac{27}{7}\frac{r\rho c}{\sigma }\]

\[\frac{72}{7}\frac{r\rho c}{\sigma }\]

\[\frac{7}{72}\frac{r\rho c}{\sigma }\]

\[\frac{27}{7}\frac{r\rho c}{\sigma }\]

\[\frac{7}{27}\frac{r\rho c}{\sigma }\]

A solid whose volume does not change with temperature floats in a liquid. For two different temperatures \[{{t}_{1}}\] and \[{{t}_{2}}\] of the liquid, fractions \[{{f}_{1}}\]and \[{{f}_{2}}\]of the volume of the solid remain submerged in the liquid. The coefficient of volume expansion of the liquid is equal to

\[\frac{{{f}_{1}}-{{f}_{2}}}{{{f}_{1}}{{t}_{1}}-{{f}_{2}}{{t}_{2}}}\]

\[\frac{{{f}_{1}}-{{f}_{2}}}{{{f}_{2}}{{t}_{1}}-{{f}_{1}}{{t}_{2}}}\]

\[\frac{{{f}_{1}}-{{f}_{2}}}{{{f}_{1}}{{t}_{1}}-{{f}_{2}}{{t}_{2}}}\]

\[\frac{{{f}_{1}}+{{f}_{2}}}{{{f}_{2}}{{t}_{1}}-{{f}_{1}}{{t}_{2}}}\]

\[\frac{{{f}_{1}}+{{f}_{2}}}{{{f}_{1}}{{t}_{1}}-{{f}_{1}}{{t}_{2}}}\]

Assuming the sun to be a spherical body of radius\[R\] at a temperature of \[T\] kelvin, evaluate the total radiant power incident on the earth at a distance r from the sun.

\[{{r}^{2}}_{0}{{R}^{2}}\sigma \frac{{{T}^{4}}}{4\pi {{r}^{2}}}\]

\[{{R}^{2}}\frac{\sigma {{T}^{4}}}{{{r}^{2}}}\]

\[4\pi {{r}^{2}}_{0}{{R}^{2}}\frac{\sigma {{T}^{4}}}{{{r}^{2}}}\]

\[\pi r_{0}^{2}{{R}^{2}}\frac{\sigma {{T}^{4}}}{{{r}^{2}}}\]

A sphere and a cube of same material and same volume are heated up to same temperature and allowed to cool in the same surroundings. The ratio of the amounts of radiations emitted in equa time intervals will be

\[\frac{1}{2}{{\left( \frac{4\pi }{3} \right)}^{1/3}}:1\]

\[{{\left( \frac{\pi }{6} \right)}^{1/3}}:1\]

\[\frac{1}{2}{{\left( \frac{4\pi }{3} \right)}^{1/3}}:1\]

Two plates identical in size, one of black and rough surface (\[{{B}_{1}}\]) and the other smooth and polished (\[{{A}_{2}}\]) are interconnected by a thin horizontal pipe with a mercury pellet at the centre. Two more plates \[{{A}_{1}}\] (identical to\[{{A}_{2}}\]) and\[{{B}_{2}}\] (identical to\[{{B}_{1}}\]) are heated to the same temperature and placed closed to the plates \[{{B}_{1}}\] and \[{{A}_{2}}\] as shown in figure. The mercury pellet

starts oscillating left and right

A piece of metal weight 46 g in air, when it is immersed in the liquid of specific gravity 1.24 at \[27{}^\circ C\]it weighs 30 g. When the temperature of liquid is raised to \[42{}^\circ C\]the metal piece weight 30.5 g, specific gravity of the liquid at \[42{}^\circ C\] is 1.20, then the linear expansion of the metal will be

\[4.316\times {{10}^{-5}}{{/}^{0}}C\]

\[3.316\times {{10}^{-5}}{{/}^{0}}C\]

\[2.316\times {{10}^{-5}}{{/}^{0}}C\]

\[4.316\times {{10}^{-5}}{{/}^{0}}C\]

The unit of percentage error is

Errors have got their own units which are different from that of physical quantity measured

Same as that of physical quantity

Different from that of physical quantity

Errors have got their own units which are different from that of physical quantity measured

A physical quantity is given by \[X={{M}^{a}}{{L}^{b}}{{T}^{c}}\]. The percentage error in measurement of \[M,L\]and T are \[\alpha ,\beta \]and \[\gamma \] respectively. Then maximum percentage error in the quantity X is [Orissa JEE 2005]

\[\frac{a}{\alpha }+\frac{b}{\beta }+\frac{c}{\gamma }\]

383 + Mcqs in Physics in NEET Page 3 McqOptions

101.	Three point charges \[+q,-2q\] and \[+q\] are placed at points \[(x=0,y=a,z=0),\] \[(x=0,y=0,z=0)\] and \[(x=a,y=0,z=0),\] respectively. The magnitude and direction of the electric dipole moment vector of this charge assembly are: [AIPMT (S) 2007]
A.	\[\sqrt{2}\,qa\] along \[+y\] direction
B.	\[\sqrt{2}\,qa\] along the line joining points \[(x=0,y=0,z=0)\] and \[(x=a,y=a,z=0)\]
C.	\[qa\] along the line joining points \[(x=0,y=0,z=0)\] and \[(x=a,y=a,z=0)\]
D.	\[\sqrt{2}\,qa\] along \[+x\] direction
Answer» C. \[qa\] along the line joining points \[(x=0,y=0,z=0)\] and \[(x=a,y=a,z=0)\]

Discussion

102.	A square surface of side L m is in the plane of the paper. A uniform electric field \[\vec{E}\] (V/m), also in the plane of the paper, is limited only to the lower half of the square surface, (see figure). The electric flux in SI units associated with the surface is: [AIPMT (S) 2006]
A.	\[E{{L}^{2}}/(2{{\varepsilon }_{0}})\]
B.	\[E{{L}^{2}}/2\]
C.	zero
D.	\[E{{L}^{2}}\]
Answer» D. \[E{{L}^{2}}\]

Discussion

103.	A parallel plate air capacitor is charged to a potential difference of V volts. After disconnecting the charging battery the distance between the plates of the capacitor is increased using an insulating handle. As a result the potential difference between the plates: [AIPMT (S) 2006]
A.	decreases
B.	does not change
C.	becomes zero
D.	increases
Answer» E.

Discussion

104.	An electric dipole of moment \[\vec{p}\] is lying along a uniform electric field \[\vec{E}\]. The work done in rotating the dipole by \[{{90}^{o}}\] is. [AIPMT (S) 2006]
A.	\[\sqrt{2}\,pE\]
B.	\[\frac{pE}{2}\]
C.	\[2\text{ }pE\]
D.	pE
Answer» E.

Discussion

105.	Two charges \[{{q}_{1}}\] and \[{{q}_{2}}\] are placed 30 cm apart as shown in the figure. A third charge \[{{q}_{3}}\] is moved along the arc of a circle of radius 40 cm from C to D. The change in the potential energy of the system is \[\frac{{{q}_{3}}}{4\pi {{\varepsilon }_{0}}}\,k,\] where k is: [AIPMT (S) 2005]
A.	\[8\,{{q}_{2}}\]
B.	\[8\,{{q}_{1}}\]
C.	\[6\,{{q}_{2}}\]
D.	\[6\,{{q}_{1}}\]
Answer» B. \[8\,{{q}_{1}}\]

Discussion

106.	As a result of change in the magnetic flux linked to the closed loop shown in the figure, an emf V volt is induced in the loop. The work done (joules) in taking a charge Q coulomb once along the loop is: [AIPMT (S) 2005]
A.	QV
B.	zero
C.	2 QV
D.	QV/2
Answer» B. zero

Discussion

107.	As per this diagram a point charge +q is placed at the origin O. Work done in taking another point chargeQ from the point A [co-ordinates \[(0,\,\,a)\]] to another points [co-ordinates \[(a,\text{ }0)\]] along the straight path AB is: [AIPMT (S) 2005]
A.	zero
B.	\[\left( \frac{-qQ}{4\pi {{\varepsilon }_{0}}}\frac{1}{{{a}^{2}}} \right)\sqrt{2}a\]
C.	\[\left( \frac{qQ}{4\pi {{\varepsilon }_{0}}}\frac{1}{{{a}^{2}}} \right)\cdot \frac{a}{\sqrt{2}}\]
D.	\[\left( \frac{qQ}{4\pi {{\varepsilon }_{0}}}\frac{1}{{{a}^{2}}} \right)\sqrt{2}a\]
Answer» B. \[\left( \frac{-qQ}{4\pi {{\varepsilon }_{0}}}\frac{1}{{{a}^{2}}} \right)\sqrt{2}a\]

Discussion

108.	A network of four capacitors of capacity equal to \[{{C}_{1}}=C,\text{ }{{C}_{2}}=2C,\text{ }{{C}_{3}}=3C\] and \[{{C}_{4}}=4C\] are connected to a battery as shown in the figure The ratio of the charges on \[{{C}_{2}}\] an \[{{C}_{4}}\] is: [AIPMT (S) 2005]
A.	\[\frac{22}{3}\]
B.	\[\frac{3}{22}\]
C.	\[\frac{7}{4}\]
D.	\[\frac{4}{7}\]
Answer» C. \[\frac{7}{4}\]

Discussion

109.	A bullet of mass 2g is having a charge of \[2\,\mu C\]. Through what potential difference must it be accelerated, starting from rest, to acquire a speed of 10 m/s? [AIPMT (S) 2004]
A.	5 kV
B.	50 kV
C.	5 V
D.	50 V
Answer» C. 5 V

Discussion

110.	An electric dipole has the magnitude of its charge as q and its dipole moment is p. It is placed in a uniform electric field E. If its dipole moment is along the direction of the field, the force on it and its potential energy are respectively: [AIPMT (S) 2004]
A.	\[2qE\] and minimum.
B.	\[qE\] and \[pE\]
C.	zero and minimum
D.	\[qE\] and maximum
Answer» D. \[qE\] and maximum

Discussion

111.	Three capacitors each of capacity \[4\,\mu F\] are to be connected in such a way that the effective capacitance is \[6\,\mu F\]. This can be done by: [AIPMT 2003]
A.	connecting two in series and one in parallel
B.	connecting two in parallel and one in series
C.	connecting all of diem in series
D.	connecting all of them in parallel
Answer» B. connecting two in parallel and one in series

Discussion

112.	A charge q is located at the centre of a cube. The electric flux through any face is: [AIPMT 2003]
A.	\[\frac{\pi q}{6(4\pi {{\varepsilon }_{0}})}\]
B.	\[\frac{q}{6(4\pi {{\varepsilon }_{0}})}\]
C.	\[\frac{2\pi q}{6(4\pi {{\varepsilon }_{0}})}\]
D.	\[\frac{4\pi q}{6(4\pi {{\varepsilon }_{0}})}\]
Answer» E.

Discussion

113.	An electron is moving round the nucleus of a hydrogen atom in a circular orbit of radius r. The coulomb force \[\vec{F}\] between the two is: [AIPMT 2003]
A.	\[k\frac{{{e}^{2}}}{{{r}^{3}}}\vec{r}\]
B.	\[-k\,\frac{{{e}^{2}}}{{{r}^{3}}}\vec{r}\]
C.	\[k\frac{{{e}^{2}}}{{{r}^{2}}}\hat{r}\]
D.	\[-k\frac{{{e}^{2}}}{{{r}^{3}}}\hat{r}\]
Answer» E.

Discussion

114.	Identical charges \[(-q)\] are placed at each corners of a cube of side b, then the electrostatic potential energy of charge \[(+q)\] placed at the centre of the cube will be:
A.	\[-\frac{4\sqrt{2}{{q}^{2}}}{\pi {{\varepsilon }_{0}}}\]
B.	\[\frac{8\sqrt{2}{{q}^{2}}}{\pi {{\varepsilon }_{0}}b}\]
C.	\[-\frac{4{{q}^{2}}}{\sqrt{3}\pi {{\varepsilon }_{0}}b}\]
D.	\[\frac{8\sqrt{2}{{q}^{2}}}{4\pi {{\varepsilon }_{0}}b}\]
Answer» D. \[\frac{8\sqrt{2}{{q}^{2}}}{4\pi {{\varepsilon }_{0}}b}\]

Discussion

115.	A capacitor of capacity \[{{C}_{1}}\] is charged upto potential V volt and then connected in parallel to an uncharged capacitor of capacity \[{{C}_{2}}\]. The final potential difference across each capacitor will be: [AIPMT 2002]
A.	\[\frac{{{C}_{2}}V}{{{C}_{1}}+{{C}_{2}}}\]
B.	\[\frac{{{C}_{1}}V}{{{C}_{1}}+{{C}_{2}}}\]
C.	\[\left( 1+\frac{{{C}_{2}}}{{{C}_{1}}} \right)V\]
D.	\[\left( 1-\frac{{{C}_{2}}}{{{C}_{1}}} \right)V\]
Answer» C. \[\left( 1+\frac{{{C}_{2}}}{{{C}_{1}}} \right)V\]

Discussion

116.	Some charge is being given to a conductor then its potential is: [AIPMT 2002]
A.	maximum at surface
B.	maximum at centre
C.	same throughout the conductor
D.	maximum somewhere between surface and centre
Answer» D. maximum somewhere between surface and centre

Discussion

117.	Torque acting on electric dipole of dipole moment \[\vec{p}\] placed in uniform electric field \[\vec{E}\] is: [AIPMT 2001]
A.	\[\vec{p}\times \vec{E}\]
B.	\[\vec{p}\,.\,\vec{E}\]
C.	\[\vec{p}\times \vec{E}\times \vec{p}\]
D.	\[\frac{\vec{E}\,.\,\vec{p}}{{{p}^{2}}}\]
Answer» B. \[\vec{p}\,.\,\vec{E}\]

Discussion

118.	A charge \[q\mu C\] is placed at the centre of a cube of a side 0.1 m, then the electric flux diverging from each face of the cube is: [AIPMT 2001]
A.	\[\frac{q\times {{10}^{-6}}}{24{{\varepsilon }_{0}}}\]
B.	\[\frac{q\times {{10}^{-4}}}{{{\varepsilon }_{0}}}\]
C.	\[\frac{q\times {{10}^{-6}}}{6{{\varepsilon }_{0}}}\]
D.	\[\frac{q\times {{10}^{-4}}}{12{{\varepsilon }_{0}}}\]
Answer» D. \[\frac{q\times {{10}^{-4}}}{12{{\varepsilon }_{0}}}\]

Discussion

119.	In a parallel plate capacitor, the distance between the plates is d and potential difference across plates is V. Energy stored per unit volume between the plates of capacitor is: [AIPMT 2001]
A.	\[\frac{{{Q}^{2}}}{2{{V}^{2}}}\]
B.	\[\frac{1}{2}{{\varepsilon }_{0}}\frac{{{V}^{2}}}{{{d}^{2}}}\]
C.	\[\frac{1}{2}\frac{{{V}^{2}}}{{{\varepsilon }_{0}}{{d}^{2}}}\]
D.	\[\frac{1}{2}{{\varepsilon }_{0}}\frac{{{V}^{2}}}{{{d}^{2}}}\]
Answer» E.

Discussion

120.	When a proton is accelerated through 1V its kinetic energy will be: [AIPMT 1999]
A.	1540 eV
B.	13.6 eV
C.	1 eV
D.	zero
Answer» D. zero

Discussion

121.	A capacitor is charged by connecting a battery across its plates. It stores energy U. Now the battery is disconnected and another identical capacitor is connected across it, then the energy stored by both capacitors of the system will be: [AIPMT 2000]
A.	U
B.	\[\frac{U}{2}\]
C.	2U
D.	\[\frac{3}{2}U\]
Answer» C. 2U

Discussion

122.	A particle of mass m and charge q is placed at rest in a uniform electric field E and then released. The kinetic energy attained by the particle after moving a distance y is : [AIPMT 1998]
A.	\[qE{{y}^{2}}\]
B.	\[q{{E}^{2}}y\]
C.	\[qEy\]
D.	\[{{q}^{2}}Ey\]
Answer» D. \[{{q}^{2}}Ey\]

Discussion

123.	A point Q lies on die perpendicular bisector of an electrical dipole of dipole moment p. If the distance of Q from the dipole is r (much larger than the size of the dipole) then electric field at Q is proportional to: [AIPMT 1998]
A.	\[{{p}^{-1}}\] and \[{{r}^{2}}\]
B.	\[p\] and \[{{r}^{-2}}\]
C.	\[{{p}^{2}}\] and \[{{r}^{-3}}\]
D.	\[p\] and \[{{r}^{-3}}\]
Answer» E.

Discussion

124.	A vessel contains \[M\] grams of water at a certain temperature and water at certain other temperature is passed into it at a. constant. Rate of\[mg/s\]. The variation - of temperature of the & mixture with time is shown in figure. The values of \[m\] and ware, respectively (the heat exchanged after a long Time (sec) time is 800 cal)
A.	40 and 2
B.	40 and 4
C.	20 and 4
D.	20 and 2
Answer» C. 20 and 4

Discussion

125.	A clock with a metal pendulum beating seconds keeps correct time at\[0{}^\circ C\]. If it loses 12.5 s a day at\[25{}^\circ C\], the coefficient of linear expansion of metal of pendulum is
A.	\[\frac{1}{86400}/k{}^\circ C\]
B.	\[\frac{1}{43200}/k{}^\circ C\]
C.	\[\frac{1}{14400}/k{}^\circ C\]
D.	\[\frac{1}{28800}/k{}^\circ C\]
Answer» B. \[\frac{1}{43200}/k{}^\circ C\]

Discussion

126.	Three discs A, B and C having radii 2m, 4m, and 6m respectively are coated with carbon black on their other surfaces. The wavelengths corresponding to maximum intensity are 300 nm, 400 nm and 500 nm, respectively. The power radiated by them are \[{{Q}_{a,\,}}{{Q}_{b,}}\,and\,{{Q}_{c}}\] respectively,
A.	\[{{Q}_{a,\,}}\]is maximum
B.	\[{{Q}_{b,}}\]is maximum
C.	\[{{Q}_{c}}\]is maximum
D.	\[{{Q}_{a,\,}}={{Q}_{b,}}\,={{Q}_{c}}\]
Answer» C. \[{{Q}_{c}}\]is maximum

Discussion

127.	A body cools in a surrounding which is at a constant temperature of\[{{\theta }_{0}}\]. Assume that it obeys Newton's law of cooling. Its temperature \[\theta \]is plotted against time \[t\]. Tangents are drawn to the curve at the points \[P(\theta ={{\theta }_{1}})\]and\[Q(\theta ={{\theta }_{2}})\]. These tangents meet the time axis at angles of \[{{\phi }_{2\,}}\] and \[{{\phi }_{1}}\], as shown
A.	\[\frac{\tan {{\phi }_{2}}}{\tan {{\theta }_{1}}}=\frac{{{\theta }_{1}}-{{\theta }_{0}}}{{{\theta }_{2}}-{{\theta }_{0}}}\]
B.	\[\frac{\tan {{\phi }_{2}}}{\tan {{\theta }_{1}}}=\frac{{{\theta }_{2}}-{{\theta }_{0}}}{{{\theta }_{1}}-{{\theta }_{0}}}\]
C.	\[\frac{\tan {{\phi }_{1}}}{\tan {{\theta }_{2}}}=\frac{{{\theta }_{1}}}{{{\theta }_{2}}}\]
D.	\[\frac{\tan {{\phi }_{1}}}{\tan {{\theta }_{2}}}=\frac{{{\theta }_{2}}}{{{\theta }_{1}}}\]
Answer» C. \[\frac{\tan {{\phi }_{1}}}{\tan {{\theta }_{2}}}=\frac{{{\theta }_{1}}}{{{\theta }_{2}}}\]

Discussion

128.	Three rods of equal length / are joined to form an equilateral triangle PQR. 0 is the mid point of R PQ. Distance OR remains same for small change in temperature. Coefficient of linear expansion for PR and RQ is same i.e. \[{{\alpha }_{2}}\] but that for PQ is \[{{\alpha }_{1}}\].Then
A.	\[{{\alpha }_{2}}=3{{\alpha }_{1}}\]
B.	\[{{\alpha }_{2}}=4{{\alpha }_{1}}\]
C.	\[{{\alpha }_{1}}=3{{\alpha }_{2}}\]
D.	\[{{\alpha }_{1}}=4{{\alpha }_{2}}\]
Answer» E.

Discussion

129.	Hot water cools from \[60{}^\circ C\]to \[50{}^\circ C\]in the first 10 minutes and to \[42{}^\circ C\] in the next 10 minutes. The temperature of the surrounding is
A.	\[5{}^\circ C\]
B.	\[10{}^\circ C\]
C.	\[15{}^\circ C~~~~\]
D.	\[20{}^\circ C\]
Answer» C. \[15{}^\circ C~~~~\]

Discussion

130.	A student takes 50 g wax (specific heat\[=0.6\text{ }kcal/kg{}^\circ C\]) and heats it till it boils. The graph between temperature and time is as follows. Heat supplied to the wax per minute ? and boiling point are, respectively
A.	500 cal, \[50{}^\circ C\]
B.	1000 cal,\[100{}^\circ C\]
C.	1500 cal,\[200{}^\circ C\]
D.	1000 cal,\[200{}^\circ C\]
Answer» D. 1000 cal,\[200{}^\circ C\]

Discussion

131.	A solid copper sphere (density \[\rho \] and specific heat capacity c) of radius \[r\] at an initial temperature 200 K is suspended inside a chamber whose walls are at almost 0 K. The time required (in \[\mu s\]) for the temperature of the sphere to drop to 100 K is
A.	\[\frac{72}{7}\frac{r\rho c}{\sigma }\]
B.	\[\frac{7}{72}\frac{r\rho c}{\sigma }\]
C.	\[\frac{27}{7}\frac{r\rho c}{\sigma }\]
D.	\[\frac{7}{27}\frac{r\rho c}{\sigma }\]
Answer» C. \[\frac{27}{7}\frac{r\rho c}{\sigma }\]

Discussion

132.	A solid whose volume does not change with temperature floats in a liquid. For two different temperatures \[{{t}_{1}}\] and \[{{t}_{2}}\] of the liquid, fractions \[{{f}_{1}}\]and \[{{f}_{2}}\]of the volume of the solid remain submerged in the liquid. The coefficient of volume expansion of the liquid is equal to
A.	\[\frac{{{f}_{1}}-{{f}_{2}}}{{{f}_{2}}{{t}_{1}}-{{f}_{1}}{{t}_{2}}}\]
B.	\[\frac{{{f}_{1}}-{{f}_{2}}}{{{f}_{1}}{{t}_{1}}-{{f}_{2}}{{t}_{2}}}\]
C.	\[\frac{{{f}_{1}}+{{f}_{2}}}{{{f}_{2}}{{t}_{1}}-{{f}_{1}}{{t}_{2}}}\]
D.	\[\frac{{{f}_{1}}+{{f}_{2}}}{{{f}_{1}}{{t}_{1}}-{{f}_{1}}{{t}_{2}}}\]
Answer» B. \[\frac{{{f}_{1}}-{{f}_{2}}}{{{f}_{1}}{{t}_{1}}-{{f}_{2}}{{t}_{2}}}\]

Discussion

133.	The wavelength of maximum energy released during an atomic explosion was \[2.93\times {{10}^{-10}}\] m. Given that Wien's constant is \[2.93\times {{10}^{-3}}\] m-K, the maximum temperature attained must be of the order of
A.	\[{{10}^{-7}}K\]
B.	\[{{10}^{7}}K\]
C.	\[{{10}^{-}}^{13}K\]
D.	\[5.86\times {{10}^{7}}K\]
Answer» C. \[{{10}^{-}}^{13}K\]

Discussion

134.	An electrically heated coil is immersed in a calorimeter containing 360 g of water at\[10{}^\circ C\]. The coil consumes energy at the rate of 90 W. The water equivalent of calorimeter and coil is 40 g. The temperature of water after 10 min is
A.	\[4.214{}^\circ C\]
B.	\[42.14{}^\circ C\]
C.	\[30{}^\circ C\]
D.	None of these
Answer» C. \[30{}^\circ C\]

Discussion

135.	Assuming the sun to be a spherical body of radius\[R\] at a temperature of \[T\] kelvin, evaluate the total radiant power incident on the earth at a distance r from the sun.
A.	\[{{r}^{2}}_{0}{{R}^{2}}\sigma \frac{{{T}^{4}}}{4\pi {{r}^{2}}}\]
B.	\[{{R}^{2}}\frac{\sigma {{T}^{4}}}{{{r}^{2}}}\]
C.	\[4\pi {{r}^{2}}_{0}{{R}^{2}}\frac{\sigma {{T}^{4}}}{{{r}^{2}}}\]
D.	\[\pi r_{0}^{2}{{R}^{2}}\frac{\sigma {{T}^{4}}}{{{r}^{2}}}\]
Answer» E.

Discussion

136.	An external pressure \[P\] is applied on a cube at \[0{}^\circ C\]so that it is equally compressed from all sides. K is the bulk modulus of the material of the cube and a is its coefficient of linear expansion. Suppose we want to bring the cube to its original size by heating. The temperature should be raised by
A.	\[\frac{3\alpha }{PK}\]
B.	\[3PK\alpha \]
C.	\[\frac{P}{3\alpha K}\]
D.	\[\frac{P}{\alpha K}\]
Answer» D. \[\frac{P}{\alpha K}\]

Discussion

137.	An incandescent lamp consuming \[P=54\text{ }W\]is immersed into a transparent calorimeter containing \[V={{10}^{3}}c{{m}^{3}}\]of water. In 420s the water is heated by\[4{}^\circ C\]. The percentage of the energy consumed by the lamp that passes out of the calorimeter in the form of radiant energy is
A.	81.5%
B.	0.26
C.	40.5%
D.	0.515
Answer» C. 40.5%

Discussion

138.	A body cools in 7 min from \[60{}^\circ C\]to\[40{}^\circ C\]. What will be its temperature after the next 7 min? The temperature of surroundings is\[10{}^\circ C\].
A.	\[28{}^\circ C\]
B.	\[25{}^\circ C\]
C.	\[30{}^\circ C\]
D.	\[22{}^\circ C\]
Answer» B. \[25{}^\circ C\]

Discussion

139.	A sphere and a cube of same material and same volume are heated up to same temperature and allowed to cool in the same surroundings. The ratio of the amounts of radiations emitted in equa time intervals will be
A.	\[1:1\]
B.	\[\frac{4\pi }{3}:1\]
C.	\[{{\left( \frac{\pi }{6} \right)}^{1/3}}:1\]
D.	\[\frac{1}{2}{{\left( \frac{4\pi }{3} \right)}^{1/3}}:1\]
Answer» D. \[\frac{1}{2}{{\left( \frac{4\pi }{3} \right)}^{1/3}}:1\]

Discussion

140.	Two plates identical in size, one of black and rough surface (\[{{B}_{1}}\]) and the other smooth and polished (\[{{A}_{2}}\]) are interconnected by a thin horizontal pipe with a mercury pellet at the centre. Two more plates \[{{A}_{1}}\] (identical to\[{{A}_{2}}\]) and\[{{B}_{2}}\] (identical to\[{{B}_{1}}\]) are heated to the same temperature and placed closed to the plates \[{{B}_{1}}\] and \[{{A}_{2}}\] as shown in figure. The mercury pellet
A.	moves to the right
B.	moves to the left
C.	remains stationary
D.	starts oscillating left and right
Answer» D. starts oscillating left and right

Discussion

141.	A piece of metal weight 46 g in air, when it is immersed in the liquid of specific gravity 1.24 at \[27{}^\circ C\]it weighs 30 g. When the temperature of liquid is raised to \[42{}^\circ C\]the metal piece weight 30.5 g, specific gravity of the liquid at \[42{}^\circ C\] is 1.20, then the linear expansion of the metal will be
A.	\[3.316\times {{10}^{-5}}{{/}^{0}}C\]
B.	\[2.316\times {{10}^{-5}}{{/}^{0}}C\]
C.	\[4.316\times {{10}^{-5}}{{/}^{0}}C\]
D.	None of these
Answer» C. \[4.316\times {{10}^{-5}}{{/}^{0}}C\]

Discussion

142.	The unit of percentage error is
A.	Same as that of physical quantity
B.	Different from that of physical quantity
C.	Percentage error is unit less
D.	Errors have got their own units which are different from that of physical quantity measured
Answer» D. Errors have got their own units which are different from that of physical quantity measured

Discussion

143.	The percentage error in the above problem is
A.	7%
B.	5.95%
C.	8.95%
D.	9.85%
Answer» D. 9.85%

Discussion

144.	A body travels uniformly a distance of (13.8 ±0.2) m in a time (4.0 ± 0.3) s. The velocity of the body within error limits is
A.	(3.45 ± 0.2) ms-1
B.	(3.45 ± 0.3) ms-1
C.	(3.45 ± 0.4) ms-1
D.	(3.45 ± 0.5) ms-1
Answer» C. (3.45 ± 0.4) ms-1

Discussion

145.	Error in the measurement of radius of a sphere is 1%. The error in the calculated value of its volume is [AFMC 2005]
A.	1%
B.	3%
C.	5%
D.	7%
Answer» C. 5%

Discussion

146.	The mean time period of second's pendulum is 2.00s and mean absolute error in the time period is 0.05s. To express maximum estimate of error, the time period should be written as
A.	(2.00 ± 0.01) s
B.	(2.00 +0.025) s
C.	(2.00 ± 0.05) s
D.	(2.00 ± 0.10) s
Answer» D. (2.00 ± 0.10) s

Discussion

147.	What is the number of significant figures in 0.310×103
A.	2
B.	3
C.	4
D.	6
Answer» C. 4

Discussion

148.	The random error in the arithmetic mean of 100 observations is x; then random error in the arithmetic mean of 400 observations would be
A.	4x
B.	\[\frac{1}{4}x\]
C.	2x
D.	\[\frac{1}{2}x\]
Answer» C. 2x

Discussion

149.	A physical quantity A is related to four observable \[a,b,c\] and d as follows, \[A=\frac{{{a}^{2}}{{b}^{3}}}{c\sqrt{d}}\], the percentage errors of measurement in \[a,b,c\] and d are 1%,3%,2% and 2% respectively. What is the percentage error in the quantity A [Kerala PET 2005]
A.	12%
B.	7%
C.	5%
D.	14%
Answer» E.

Discussion

150.	A physical quantity is given by \[X={{M}^{a}}{{L}^{b}}{{T}^{c}}\]. The percentage error in measurement of \[M,L\]and T are \[\alpha ,\beta \]and \[\gamma \] respectively. Then maximum percentage error in the quantity X is [Orissa JEE 2005]
A.	\[a\alpha +b\beta +c\gamma \]
B.	\[a\alpha +b\beta -c\gamma \]
C.	\[\frac{a}{\alpha }+\frac{b}{\beta }+\frac{c}{\gamma }\]
D.	None of these
Answer» B. \[a\alpha +b\beta -c\gamma \]

Discussion

Explore topic-wise MCQs in NEET.

Three point charges \[+q,-2q\] and \[+q\] are placed at points \[(x=0,y=a,z=0),\] \[(x=0,y=0,z=0)\] and \[(x=a,y=0,z=0),\] respectively. The magnitude and direction of the electric dipole moment vector of this charge assembly are: [AIPMT (S) 2007]

A square surface of side L m is in the plane of the paper. A uniform electric field \[\vec{E}\] (V/m), also in the plane of the paper, is limited only to the lower half of the square surface, (see figure). The electric flux in SI units associated with the surface is: [AIPMT (S) 2006]

A parallel plate air capacitor is charged to a potential difference of V volts. After disconnecting the charging battery the distance between the plates of the capacitor is increased using an insulating handle. As a result the potential difference between the plates: [AIPMT (S) 2006]

An electric dipole of moment \[\vec{p}\] is lying along a uniform electric field \[\vec{E}\]. The work done in rotating the dipole by \[{{90}^{o}}\] is. [AIPMT (S) 2006]

As a result of change in the magnetic flux linked to the closed loop shown in the figure, an emf V volt is induced in the loop. The work done (joules) in taking a charge Q coulomb once along the loop is: [AIPMT (S) 2005]

As per this diagram a point charge +q is placed at the origin O. Work done in taking another point chargeQ from the point A [co-ordinates \[(0,\,\,a)\]] to another points [co-ordinates \[(a,\text{ }0)\]] along the straight path AB is: [AIPMT (S) 2005]

A network of four capacitors of capacity equal to \[{{C}_{1}}=C,\text{ }{{C}_{2}}=2C,\text{ }{{C}_{3}}=3C\] and \[{{C}_{4}}=4C\] are connected to a battery as shown in the figure The ratio of the charges on \[{{C}_{2}}\] an \[{{C}_{4}}\] is: [AIPMT (S) 2005]

A bullet of mass 2g is having a charge of \[2\,\mu C\]. Through what potential difference must it be accelerated, starting from rest, to acquire a speed of 10 m/s? [AIPMT (S) 2004]

An electric dipole has the magnitude of its charge as q and its dipole moment is p. It is placed in a uniform electric field E. If its dipole moment is along the direction of the field, the force on it and its potential energy are respectively: [AIPMT (S) 2004]

Three capacitors each of capacity \[4\,\mu F\] are to be connected in such a way that the effective capacitance is \[6\,\mu F\]. This can be done by: [AIPMT 2003]

A charge q is located at the centre of a cube. The electric flux through any face is: [AIPMT 2003]

An electron is moving round the nucleus of a hydrogen atom in a circular orbit of radius r. The coulomb force \[\vec{F}\] between the two is: [AIPMT 2003]

Identical charges \[(-q)\] are placed at each corners of a cube of side b, then the electrostatic potential energy of charge \[(+q)\] placed at the centre of the cube will be:

A capacitor of capacity \[{{C}_{1}}\] is charged upto potential V volt and then connected in parallel to an uncharged capacitor of capacity \[{{C}_{2}}\]. The final potential difference across each capacitor will be: [AIPMT 2002]

Some charge is being given to a conductor then its potential is: [AIPMT 2002]

Torque acting on electric dipole of dipole moment \[\vec{p}\] placed in uniform electric field \[\vec{E}\] is: [AIPMT 2001]

A charge \[q\mu C\] is placed at the centre of a cube of a side 0.1 m, then the electric flux diverging from each face of the cube is: [AIPMT 2001]

In a parallel plate capacitor, the distance between the plates is d and potential difference across plates is V. Energy stored per unit volume between the plates of capacitor is: [AIPMT 2001]

When a proton is accelerated through 1V its kinetic energy will be: [AIPMT 1999]

A capacitor is charged by connecting a battery across its plates. It stores energy U. Now the battery is disconnected and another identical capacitor is connected across it, then the energy stored by both capacitors of the system will be: [AIPMT 2000]

A particle of mass m and charge q is placed at rest in a uniform electric field E and then released. The kinetic energy attained by the particle after moving a distance y is : [AIPMT 1998]

A point Q lies on die perpendicular bisector of an electrical dipole of dipole moment p. If the distance of Q from the dipole is r (much larger than the size of the dipole) then electric field at Q is proportional to: [AIPMT 1998]

A clock with a metal pendulum beating seconds keeps correct time at\[0{}^\circ C\]. If it loses 12.5 s a day at\[25{}^\circ C\], the coefficient of linear expansion of metal of pendulum is

Three rods of equal length / are joined to form an equilateral triangle PQR. 0 is the mid point of R PQ. Distance OR remains same for small change in temperature. Coefficient of linear expansion for PR and RQ is same i.e. \[{{\alpha }_{2}}\] but that for PQ is \[{{\alpha }_{1}}\].Then

Hot water cools from \[60{}^\circ C\]to \[50{}^\circ C\]in the first 10 minutes and to \[42{}^\circ C\] in the next 10 minutes. The temperature of the surrounding is

A student takes 50 g wax (specific heat\[=0.6\text{ }kcal/kg{}^\circ C\]) and heats it till it boils. The graph between temperature and time is as follows. Heat supplied to the wax per minute ? and boiling point are, respectively

A solid copper sphere (density \[\rho \] and specific heat capacity c) of radius \[r\] at an initial temperature 200 K is suspended inside a chamber whose walls are at almost 0 K. The time required (in \[\mu s\]) for the temperature of the sphere to drop to 100 K is

The wavelength of maximum energy released during an atomic explosion was \[2.93\times {{10}^{-10}}\] m. Given that Wien's constant is \[2.93\times {{10}^{-3}}\] m-K, the maximum temperature attained must be of the order of

An electrically heated coil is immersed in a calorimeter containing 360 g of water at\[10{}^\circ C\]. The coil consumes energy at the rate of 90 W. The water equivalent of calorimeter and coil is 40 g. The temperature of water after 10 min is

Assuming the sun to be a spherical body of radius\[R\] at a temperature of \[T\] kelvin, evaluate the total radiant power incident on the earth at a distance r from the sun.

A body cools in 7 min from \[60{}^\circ C\]to\[40{}^\circ C\]. What will be its temperature after the next 7 min? The temperature of surroundings is\[10{}^\circ C\].

A sphere and a cube of same material and same volume are heated up to same temperature and allowed to cool in the same surroundings. The ratio of the amounts of radiations emitted in equa time intervals will be

The unit of percentage error is

The percentage error in the above problem is

A body travels uniformly a distance of (13.8 ±0.2) m in a time (4.0 ± 0.3) s. The velocity of the body within error limits is

Error in the measurement of radius of a sphere is 1%. The error in the calculated value of its volume is [AFMC 2005]

The mean time period of second's pendulum is 2.00s and mean absolute error in the time period is 0.05s. To express maximum estimate of error, the time period should be written as

What is the number of significant figures in 0.310×103

The random error in the arithmetic mean of 100 observations is x; then random error in the arithmetic mean of 400 observations would be

A physical quantity A is related to four observable \[a,b,c\] and d as follows, \[A=\frac{{{a}^{2}}{{b}^{3}}}{c\sqrt{d}}\], the percentage errors of measurement in \[a,b,c\] and d are 1%,3%,2% and 2% respectively. What is the percentage error in the quantity A [Kerala PET 2005]

A physical quantity is given by \[X={{M}^{a}}{{L}^{b}}{{T}^{c}}\]. The percentage error in measurement of \[M,L\]and T are \[\alpha ,\beta \]and \[\gamma \] respectively. Then maximum percentage error in the quantity X is [Orissa JEE 2005]