12583 + Mcqs in Physics Page 184 McqOptions

9151.	Laser beams are used to measure long distances because [DCE 2002, 03]
A.	They are monochromatic
B.	They are highly polarised
C.	They are coherent
D.	They have high degree of parallelism
Answer» E.

Discussion

9152.	Assertion : Mass of moving photon varies inversely as the wavelength. Reason : Energy of the particle \[=\text{ Mass }\times \text{ (Speed of light}{{\text{)}}^{\text{2}}}\] [AIIMS 2000]
A.	If both assertion and reason are true and the reason is the correct explanation of the assertion.
B.	If both assertion and reason are true but reason is not the correct explanation of the assertion.
C.	If assertion is true but reason is false.
D.	If the assertion and reason both are false.
E.	If assertion is false but reason is true.
Answer» C. If assertion is true but reason is false.

Discussion

9153.	Whenever a hydrogen atom emits a photon in the Balmer series [KCET 2002]
A.	It need not emit any more photon
B.	It may emit another photon in the Paschen series
C.	It must emit another photon in the Lyman series
D.	It may emit another photon in the Balmer series
Answer» D. It may emit another photon in the Balmer series

Discussion

9154.	Assertion : Soldiers are asked to break steps while crossing the bridge. Reason : The frequency of marching may be equal to the natural frequency of bridge and may lead to resonance which can break the bridge. [AIIMS 2001]
A.	If both assertion and reason are true and the reason is the correct explanation of the assertion.
B.	If both assertion and reason are true but reason is not the correct explanation of the assertion.
C.	If assertion is true but reason is false.
D.	If the assertion and reason both are false.
E.	If assertion is false but reason is true.
Answer» B. If both assertion and reason are true but reason is not the correct explanation of the assertion.

Discussion

9155.	Assertion : Gauss theorem is not applicable in magnetism. Reason : Mono magnetic pole does not exist.
A.	If both assertion and reason are true and the reason is the correct explanation of the assertion.
B.	If both assertion and reason are true but reason is not the correct explanation of the assertion.
C.	If assertion is true but reason is false.
D.	If the assertion and reason both are false.
E.	If assertion is false but reason is true.
Answer» B. If both assertion and reason are true but reason is not the correct explanation of the assertion.

Discussion

9156.	Work done in converting one gram of ice at ?10°C into steam at 100°C is [MP PET/PMT 1988; EAMCET (Med.) 1995; MP PMT 2003]
A.	3045 J
B.	6056 J
C.	721 J
D.	616 J
Answer» B. 6056 J

Discussion

9157.	Assertion : The amplitude of oscillation can never be infinite. Reason : The energy of oscillator is continuously dissipated.
A.	If both assertion and reason are true and the reason is the correct explanation of the assertion.
B.	If both assertion and reason are true but reason is not the correct explanation of the assertion.
C.	If assertion is true but reason is false.
D.	If the assertion and reason both are false.
E.	If assertion is false but reason is true.
Answer» B. If both assertion and reason are true but reason is not the correct explanation of the assertion.

Discussion

9158.	Weightlessness experienced while orbiting the earth in space-ship, is the result of [NCERT 1978; DPMT 1982]
A.	Inertia
B.	Acceleration
C.	Zero gravity
D.	Free fall towards earth
Answer» E.

Discussion

9159.	Assertion : The e.m.f. of the driver cell in the potentiometer experiment should be greater than the e.m.f. of the cell to be determined. Reason : The fall of potential across the potentiometer wire should not be less than the e.m.f. of the cell to be determined.
A.	If both assertion and reason are true and the reason is the correct explanation of the assertion.
B.	If both assertion and reason are true but reason is not the correct explanation of the assertion.
C.	If assertion is true but reason is false.
D.	If the assertion and reason both are false.
E.	If assertion is false but reason is true.
Answer» B. If both assertion and reason are true but reason is not the correct explanation of the assertion.

Discussion

9160.	In Milikan's oil drop experiment, a charged drop falls with terminal velocity V. If an electric field E is applied in vertically upward direction then it starts moving in upward direction with terminal velocity 2V. If magnitude of electric field is decreased to \[\frac{E}{2}\], then terminal velocity will become [CBSE PMT 1999]
A.	\[\frac{V}{2}\]
B.	V
C.	\[\frac{3V}{2}\]
D.	2V
Answer» D. 2V

Discussion

9161.	A transformer connected to 220 volt line shows an output of 2 A at 11000 volt. The efficiency is 100%. The current drawn from the line is [MP PMT 1995]
A.	100 A
B.	200 A
C.	22 A
D.	11 A
Answer» B. 200 A

Discussion

9162.	The resultant of two vectors \[\overrightarrow{P}\] and \[\overrightarrow{Q}\] is \[\overrightarrow{R}.\] If Q is doubled, the new resultant is perpendicular to P. Then R equals
A.	P
B.	(P+Q)
C.	Q
D.	(P?Q)
Answer» D. (P?Q)

Discussion

9163.	Assertion : The alternating current lags behind the e.m.f. by a phase angle of \[\pi /2\], when ac flows through an inductor. Reason : The inductive reactance increases as the frequency of ac source decreases.
A.	If both assertion and reason are true and the reason is the correct explanation of the assertion.
B.	If both assertion and reason are true but reason is not the correct explanation of the assertion.
C.	If assertion is true but reason is false.
D.	If the assertion and reason both are false.
E.	If assertion is false but reason is true.
Answer» D. If the assertion and reason both are false.

Discussion

9164.	Radio frequency choke uses core of [AFMC 2004]
A.	Air
B.	Iron
C.	Air and iron
D.	None of these
Answer» B. Iron

Discussion

9165.	Assertion : In everyday life the Doppler?s effect is observed readily for sound waves than light waves. Reason : Velocity of light is greater than that of sound. [AIIMS 1995]
A.	If both assertion and reason are true and the reason is the correct explanation of the assertion.
B.	If both assertion and reason are true but reason is not the correct explanation of the assertion.
C.	If assertion is true but reason is false.
D.	If the assertion and reason both are false.
E.	If assertion is false but reason is true.
Answer» C. If assertion is true but reason is false.

Discussion

9166.	Assertion : In Young?s experiment, the fringe width for dark fringes is different from that for white fringes. Reason : In Young?s double slit experiment the fringes are performed with a source of white light, then only black and bright fringes are observed. [AIIMS 2001]
A.	If both assertion and reason are true and the reason is the correct explanation of the assertion.
B.	If both assertion and reason are true but reason is not the correct explanation of the assertion.
C.	If assertion is true but reason is false.
D.	If the assertion and reason both are false.
E.	If assertion is false but reason is true.
Answer» E. If assertion is false but reason is true.

Discussion

9167.	Assertion : Coloured spectrum is seen when we look through a muslin cloth. Reason : It is due to the diffraction of white light on passing through fine slits. [AIIMS 2002]
A.	If both assertion and reason are true and the reason is the correct explanation of the assertion.
B.	If both assertion and reason are true but reason is not the correct explanation of the assertion.
C.	If assertion is true but reason is false.
D.	If the assertion and reason both are false.
E.	If assertion is false but reason is true.
Answer» B. If both assertion and reason are true but reason is not the correct explanation of the assertion.

Discussion

9168.	The radii of two planets are respectively \[{{R}_{1}}\] and \[{{R}_{2}}\] and their densities are respectively \[{{\rho }_{1}}\] and \[{{\rho }_{2}}\]. The ratio of the accelerations due to gravity at their surfaces is [MP PET 1994]
A.	\[{{g}_{1}}:{{g}_{2}}=\frac{{{\rho }_{1}}}{R_{1}^{2}}:\frac{{{\rho }_{2}}}{R_{2}^{2}}\]
B.	\[{{g}_{1}}:{{g}_{2}}={{R}_{1}}{{R}_{2}}:{{\rho }_{1}}{{\rho }_{2}}\]
C.	\[{{g}_{1}}:{{g}_{2}}={{R}_{1}}{{\rho }_{2}}:{{R}_{2}}{{\rho }_{1}}\]
D.	\[{{g}_{1}}:{{g}_{2}}={{R}_{1}}{{\rho }_{1}}:{{R}_{2}}{{\rho }_{2}}\]
Answer» E.

Discussion

9169.	Magnitude of vector which comes on addition of two vectors, \[6\hat{i}+7\hat{j}\] and \[3\hat{i}+4\hat{j}\] is [BHU 2000]
A.	\[\sqrt{136}\]
B.	\[\sqrt{13.2}\]
C.	\[\sqrt{202}\]
D.	\[\sqrt{160}\]
Answer» D. \[\sqrt{160}\]

Discussion

9170.	A \[700\,pF\] capacitor is charged by a \[50V\] battery. The electrostatic energy stored by it is [MH CET 2000]
A.	\[17.0\times {{10}^{-8}}\,J\]
B.	\[13.6\times {{10}^{-9}}\,J\]
C.	\[9.5\times {{10}^{-9}}\,J\]
D.	\[8.7\times {{10}^{-7}}\,J\]
Answer» E.

Discussion

9171.	Two small spheres each having the charge \[+Q\] are suspended by insulating threads of length \[L\] from a hook. This arrangement is taken in space where there is no gravitational effect, then the angle between the two suspensions and the tension in each will be [IIT 1986]
A.	\[{{180}^{o}},\,\frac{1}{4\pi {{\varepsilon }_{0}}}\frac{{{Q}^{2}}}{{{(2L)}^{2}}}\]
B.	\[{{90}^{o}},\,\frac{1}{4\pi {{\varepsilon }_{0}}}\frac{{{Q}^{2}}}{{{L}^{2}}}\]
C.	\[{{180}^{o}},\,\frac{1}{4\pi {{\varepsilon }_{0}}}\frac{{{Q}^{2}}}{2{{L}^{2}}}\]
D.	\[{{180}^{o}},\,\frac{1}{4\pi {{\varepsilon }_{0}}}\frac{{{Q}^{2}}}{{{L}^{2}}}\]
Answer» B. \[{{90}^{o}},\,\frac{1}{4\pi {{\varepsilon }_{0}}}\frac{{{Q}^{2}}}{{{L}^{2}}}\]

Discussion

9172.	Assertion : The slope of momentum versus time curve give us the acceleration. Reason : Acceleration is given by the rate of change of momentum.
A.	If both assertion and reason are true and the reason is the correct explanation of the assertion.
B.	If both assertion and reason are true but reason is not the correct explanation of the assertion.
C.	If assertion is true but reason is false.
D.	If the assertion and reason both are false.
E.	If assertion is false but reason is true.
Answer» E. If assertion is false but reason is true.

Discussion

9173.	The moon's radius is 1/4 that of the earth and its mass is 1/80 times that of the earth. If g represents the acceleration due to gravity on the surface of the earth, that on the surface of the moon is [MP PMT 1997; MP PET 2000, 01; RPET 2000; Pb. PET 2001]
A.	g/4
B.	g/5
C.	g/6
D.	g/8
Answer» C. g/6

Discussion

9174.	A body has a weight 90 kg on the earth's surface, the mass of the moon is 1/9 that of the earth's mass and its radius is 1/2 that of the earth's radius. On the moon the weight of the body is [Pb. PET 2003]
A.	45 kg
B.	202.5 kg
C.	90 kg
D.	40 kg
Answer» E.

Discussion

9175.	64 drops of mercury each charged to a potential of \[10V\]. They are combined to form one bigger drop. The potential of this drop will be (Assume all the drops to be spherical) [MP PET 2003]
A.	160 V
B.	80 V
C.	10 V
D.	640 V
Answer» B. 80 V

Discussion

9176.	Assertion : The acceleration produced by a force in the motion of a body depends only upon its mass. Reason : Larger is the mass of the body, lesser will be the acceleration produced.
A.	If both assertion and reason are true and the reason is the correct explanation of the assertion.
B.	If both assertion and reason are true but reason is not the correct explanation of the assertion.
C.	If assertion is true but reason is false.
D.	If the assertion and reason both are false.
E.	If assertion is false but reason is true.
Answer» C. If assertion is true but reason is false.

Discussion

9177.	Assertion : Electron capture occurs more often than positron emission in heavy elements. Reason : Heavy elements exhibit radioactivity.
A.	If both assertion and reason are true and the reason is the correct explanation of the assertion.
B.	If both assertion and reason are true but reason is not the correct explanation of the assertion.
C.	If assertion is true but reason is false.
D.	If the assertion and reason both are false.
E.	If assertion is false but reason is true.
Answer» C. If assertion is true but reason is false.

Discussion

9178.	The ratio of the longest to shortest wavelengths in Brackett series of hydrogen spectra is [EAMCET (Engg.) 2000]
A.	\[\frac{25}{9}\]
B.	\[\frac{17}{6}\]
C.	\[\frac{9}{5}\]
D.	\[\frac{4}{3}\]
Answer» B. \[\frac{17}{6}\]

Discussion

9179.	The magnetic field at the centre of coil of n turns, bent in the form of a square of side 2l , carrying current i, is [AMU (Engg.) 1999]
A.	\[\frac{\sqrt{2}{{\mu }_{0}}nI}{\pi l}\]
B.	\[\frac{\sqrt{2}{{\mu }_{0}}nI}{2\pi l}\]
C.	\[\frac{\sqrt{2}{{\mu }_{0}}nI}{4\pi l}\]
D.	\[\frac{2{{\mu }_{0}}nI}{\pi l}\]
Answer» B. \[\frac{\sqrt{2}{{\mu }_{0}}nI}{2\pi l}\]

Discussion

9180.	The peak value of an alternating e.m.f. E is given by \[E={{E}_{0}}\cos \omega \,t\]is 10 volts and its frequency is 50 Hz. At time\[t=\frac{1}{600}sec\], the instantaneous e.m.f. is [MP PMT 1990; MP PET 2004]
A.	10 V
B.	\[5\sqrt{3}\,V\]
C.	5 V
D.	1 V
Answer» C. 5 V

Discussion

9181.	A capillary tube when immersed vertically in liquid records a rise of 3 cm. If the tube is immersed in the liquid at an angle of \[{{60}^{0}}\]with the vertical. The length of the liquid column along the tube is [MH CET (Med.)1999]
A.	9cm
B.	6cm
C.	3cm
D.	2cm
Answer» C. 3cm

Discussion

9182.	Assertion : The properties of paramagnetic and ferromagnetic substance are not effected by heating. Reason : As temperature rises, the alignment of molecular magnets gradually decreases.
A.	If both assertion and reason are true and the reason is the correct explanation of the assertion.
B.	If both assertion and reason are true but reason is not the correct explanation of the assertion.
C.	If assertion is true but reason is false.
D.	If the assertion and reason both are false.
E.	If assertion is false but reason is true.
Answer» F.

Discussion

9183.	A particle moving along the x-axis executes simple harmonic motion, then the force acting on it is given by [CBSE PMT 1994]
A.	? A Kx
B.	A cos (Kx)
C.	A exp (? Kx)
D.	A Kx Where A and K are positive constants
Answer» B. A cos (Kx)

Discussion

9184.	The energy required to excite an electron from the ground state of hydrogen atom to the first excited state, is [Pb. PMT 1999]
A.	\[1.602\times {{10}^{-14}}\,J\]
B.	\[1.619\times {{10}^{-16}}\,J\]
C.	\[1.632\times {{10}^{-18}}J\]
D.	\[1.656\times {{10}^{-20}}J\]
Answer» D. \[1.656\times {{10}^{-20}}J\]

Discussion

9185.	Assertion : On going away from a point charge or a small electric dipole, electric field decreases at the same rate in both the cases. Reason : Electric field is inversely proportional to square of distance from the charge or an electric dipole.
A.	If both assertion and reason are true and the reason is the correct explanation of the assertion.
B.	If both assertion and reason are true but reason is not the correct explanation of the assertion.
C.	If assertion is true but reason is false.
D.	If the assertion and reason both are false.
E.	If assertion is false but reason is true.
Answer» E. If assertion is false but reason is true.

Discussion

9186.	Assertion : For higher temperature, the peak emission wavelength of a black body shifts to lower wavelengths. Reason : Peak emission wavelength of a blackbody is proportional to the fourth power of temperature. [AIIMS 2005]
A.	If both assertion and reason are true and the reason is the correct explanation of the assertion.
B.	If both assertion and reason are true but reason is not the correct explanation of the assertion.
C.	If assertion is true but reason is false.
D.	If the assertion and reason both are false.
E.	If assertion is false but reason is true.
Answer» D. If the assertion and reason both are false.

Discussion

9187.	A conductor has \[14.4\times {{10}^{-19}}coulombs\] positive charge. The conductor has (Charge on electron \[=1.6\times {{10}^{-19}}coulombs\])
A.	9 electrons in excess
B.	27 electrons in short
C.	27 electrons in excess
D.	9 electrons in short
Answer» E.

Discussion

9188.	Assertion : V-i characteristic of P-N junction diode is same as that of any other conductor. Reason : P-N junction diode behave as conductor at room temperature.
A.	If both assertion and reason are true and the reason is the correct explanation of the assertion.
B.	If both assertion and reason are true but reason is not the correct explanation of the assertion.
C.	If assertion is true but reason is false.
D.	If the assertion and reason both are false.
E.	If assertion is false but reason is true.
Answer» E. If assertion is false but reason is true.

Discussion

9189.	Assertion : The current gain in common base circuit is always less than one. Reason : At constant collector voltage the change in collector current is more than the change in emitter current.
A.	If both assertion and reason are true and the reason is the correct explanation of the assertion.
B.	If both assertion and reason are true but reason is not the correct explanation of the assertion.
C.	If assertion is true but reason is false.
D.	If the assertion and reason both are false.
E.	If assertion is false but reason is true.
Answer» D. If the assertion and reason both are false.

Discussion

9190.	Assertion : The electrical conductivity of earth's atmosphere decreases with altitude. Reason : The high energy particles (i.e. g-rays and cosmic rays) coming from outer space and entering our earth's atmosphere cause ionisation of the atoms of the gases present there and the pressure of gases decreases with increase in altitude.
A.	If both assertion and reason are true and the reason is the correct explanation of the assertion.
B.	If both assertion and reason are true but reason is not the correct explanation of the assertion.
C.	If assertion is true but reason is false.
D.	If the assertion and reason both are false.
E.	If assertion is false but reason is true.
Answer» F.

Discussion

9191.	Water rises upto 10 cm height in a long capillary tube. If this tube is immersed in water so that the height above the water surface is only 8 cm, then [MP PMT 1991]
A.	Water flows out continuously from the upper end
B.	Water rises upto upper end and forms a spherical surface
C.	Water only rises upto 6 cm height
D.	Water does not rise at all
Answer» C. Water only rises upto 6 cm height

Discussion

9192.	The minimum charge on an object is
A.	1 coulomb
B.	1 stat coulomb
C.	\[1.6\times {{10}^{-19}}\]coulomb
D.	\[3.2\times {{10}^{-19}}\]coulomb
Answer» D. \[3.2\times {{10}^{-19}}\]coulomb

Discussion

9193.	An electric current passes through a long straight wire. At a distance 5 cm from the wire, The magnetic field is B. The field at 20 cm from the wire would be [CPMT 2001; Pb PET 2002]
A.	\[\frac{B}{6}\]
B.	\[\frac{B}{4}\]
C.	\[\frac{B}{3}\]
D.	\[\frac{B}{2}\]
Answer» C. \[\frac{B}{3}\]

Discussion

9194.	An electron is revolving round a proton, producing a magnetic field of 16 weber/m2 in a circular orbit of radius 1Å. It?s angular velocity will be [RPMT 2002]
A.	1017 rad/sec
B.	1/2p ´ 1012 rad/sec
C.	2 p ´ 1012 rad/sec
D.	4 p ´ 1012 rad/sec
Answer» B. 1/2p ´ 1012 rad/sec

Discussion

9195.	Two protons A and B are placed in space between plates of a parallel plate capacitor charged upto V volts (See fig.) Forces on protons are \[{{F}_{A}}\] and \[{{F}_{B}}\], then [RPET 1999]
A.	\[{{F}_{A}}>{{F}_{B}}\]
B.	\[{{F}_{A}}<{{F}_{B}}\]
C.	\[{{F}_{A}}={{F}_{B}}\]
D.	Nothing can be said
Answer» D. Nothing can be said

Discussion

9196.	In transformer, core is made of soft iron to reduce [AIIMS 1998; UPSEAT 2001; AFMC 2005]
A.	Hysteresis losses
B.	Eddy current losses
C.	Force opposing electric current
D.	None of the above
Answer» B. Eddy current losses

Discussion

9197.	A long straight wire carrying current of 30A is placed in an external uniform magnetic field of induction 4 ´ 10?4T. The magnetic field is acting parallel to the direction of current. The magnitude of the resultant magnetic induction in tesla at a point 2.0 cm away from the wire is [EAMCET 2003]
A.	10?4
B.	3 ´ 10?4
C.	5 ´ 10?4
D.	6 ´ 10?4
Answer» D. 6 ´ 10?4

Discussion

9198.	Acceleration due to gravity on moon is 1/6 of the acceleration due to gravity on earth. If the ratio of densities of earth \[({{\rho }_{e}})\] and moon \[({{\rho }_{m}})\] is \[\left( \frac{{{\rho }_{e}}}{{{\rho }_{m}}} \right)=\frac{5}{3}\] then radius of moon Rm in terms of Re will be [MP PMT 2003]
A.	\[\frac{5}{18}{{R}_{e}}\]
B.	\[\frac{1}{6}{{R}_{e}}\]
C.	\[\frac{3}{18}{{R}_{e}}\]
D.	\[\frac{1}{2\sqrt{3}}{{R}_{e}}\]
Answer» B. \[\frac{1}{6}{{R}_{e}}\]

Discussion

9199.	Quantity that remains unchanged in a transformer is [MP PMT/PET 1998; AIIMS 1999; J & K CET 2005]
A.	Voltage
B.	Current
C.	Frequency
D.	None of the above
Answer» D. None of the above

Discussion

9200.	A parallel plate air capacitor is charged and then isolated. When a dielectric material is inserted between the plates of the capacitor, then which of the following does not change [Orissa JEE 2003]
A.	Electric field between the plates
B.	Potential difference across the plates
C.	Charge on the plates
D.	Energy stored in the capacitor
Answer» D. Energy stored in the capacitor

Discussion

Explore topic-wise MCQs in Joint Entrance Exam - Main (JEE Main).

Laser beams are used to measure long distances because [DCE 2002, 03]

Assertion : Mass of moving photon varies inversely as the wavelength. Reason : Energy of the particle \[=\text{ Mass }\times \text{ (Speed of light}{{\text{)}}^{\text{2}}}\] [AIIMS 2000]

Whenever a hydrogen atom emits a photon in the Balmer series [KCET 2002]

Assertion : Soldiers are asked to break steps while crossing the bridge. Reason : The frequency of marching may be equal to the natural frequency of bridge and may lead to resonance which can break the bridge. [AIIMS 2001]

Assertion : Gauss theorem is not applicable in magnetism. Reason : Mono magnetic pole does not exist.

Work done in converting one gram of ice at ?10°C into steam at 100°C is [MP PET/PMT 1988; EAMCET (Med.) 1995; MP PMT 2003]

Assertion : The amplitude of oscillation can never be infinite. Reason : The energy of oscillator is continuously dissipated.

Weightlessness experienced while orbiting the earth in space-ship, is the result of [NCERT 1978; DPMT 1982]

Assertion : The e.m.f. of the driver cell in the potentiometer experiment should be greater than the e.m.f. of the cell to be determined. Reason : The fall of potential across the potentiometer wire should not be less than the e.m.f. of the cell to be determined.

A transformer connected to 220 volt line shows an output of 2 A at 11000 volt. The efficiency is 100%. The current drawn from the line is [MP PMT 1995]

The resultant of two vectors \[\overrightarrow{P}\] and \[\overrightarrow{Q}\] is \[\overrightarrow{R}.\] If Q is doubled, the new resultant is perpendicular to P. Then R equals

Assertion : The alternating current lags behind the e.m.f. by a phase angle of \[\pi /2\], when ac flows through an inductor. Reason : The inductive reactance increases as the frequency of ac source decreases.

Radio frequency choke uses core of [AFMC 2004]

Assertion : In everyday life the Doppler?s effect is observed readily for sound waves than light waves. Reason : Velocity of light is greater than that of sound. [AIIMS 1995]

Assertion : In Young?s experiment, the fringe width for dark fringes is different from that for white fringes. Reason : In Young?s double slit experiment the fringes are performed with a source of white light, then only black and bright fringes are observed. [AIIMS 2001]

Assertion : Coloured spectrum is seen when we look through a muslin cloth. Reason : It is due to the diffraction of white light on passing through fine slits. [AIIMS 2002]

The radii of two planets are respectively \[{{R}_{1}}\] and \[{{R}_{2}}\] and their densities are respectively \[{{\rho }_{1}}\] and \[{{\rho }_{2}}\]. The ratio of the accelerations due to gravity at their surfaces is [MP PET 1994]

Magnitude of vector which comes on addition of two vectors, \[6\hat{i}+7\hat{j}\] and \[3\hat{i}+4\hat{j}\] is [BHU 2000]

A \[700\,pF\] capacitor is charged by a \[50V\] battery. The electrostatic energy stored by it is [MH CET 2000]

Two small spheres each having the charge \[+Q\] are suspended by insulating threads of length \[L\] from a hook. This arrangement is taken in space where there is no gravitational effect, then the angle between the two suspensions and the tension in each will be [IIT 1986]

Assertion : The slope of momentum versus time curve give us the acceleration. Reason : Acceleration is given by the rate of change of momentum.

The moon's radius is 1/4 that of the earth and its mass is 1/80 times that of the earth. If g represents the acceleration due to gravity on the surface of the earth, that on the surface of the moon is [MP PMT 1997; MP PET 2000, 01; RPET 2000; Pb. PET 2001]

A body has a weight 90 kg on the earth's surface, the mass of the moon is 1/9 that of the earth's mass and its radius is 1/2 that of the earth's radius. On the moon the weight of the body is [Pb. PET 2003]

64 drops of mercury each charged to a potential of \[10V\]. They are combined to form one bigger drop. The potential of this drop will be (Assume all the drops to be spherical) [MP PET 2003]

Assertion : The acceleration produced by a force in the motion of a body depends only upon its mass. Reason : Larger is the mass of the body, lesser will be the acceleration produced.

Assertion : Electron capture occurs more often than positron emission in heavy elements. Reason : Heavy elements exhibit radioactivity.

The ratio of the longest to shortest wavelengths in Brackett series of hydrogen spectra is [EAMCET (Engg.) 2000]

The magnetic field at the centre of coil of n turns, bent in the form of a square of side 2l , carrying current i, is [AMU (Engg.) 1999]

The peak value of an alternating e.m.f. E is given by \[E={{E}_{0}}\cos \omega \,t\]is 10 volts and its frequency is 50 Hz. At time\[t=\frac{1}{600}sec\], the instantaneous e.m.f. is [MP PMT 1990; MP PET 2004]

A capillary tube when immersed vertically in liquid records a rise of 3 cm. If the tube is immersed in the liquid at an angle of \[{{60}^{0}}\]with the vertical. The length of the liquid column along the tube is [MH CET (Med.)1999]

Assertion : The properties of paramagnetic and ferromagnetic substance are not effected by heating. Reason : As temperature rises, the alignment of molecular magnets gradually decreases.

A particle moving along the x-axis executes simple harmonic motion, then the force acting on it is given by [CBSE PMT 1994]

The energy required to excite an electron from the ground state of hydrogen atom to the first excited state, is [Pb. PMT 1999]

Assertion : On going away from a point charge or a small electric dipole, electric field decreases at the same rate in both the cases. Reason : Electric field is inversely proportional to square of distance from the charge or an electric dipole.

Assertion : For higher temperature, the peak emission wavelength of a black body shifts to lower wavelengths. Reason : Peak emission wavelength of a blackbody is proportional to the fourth power of temperature. [AIIMS 2005]

A conductor has \[14.4\times {{10}^{-19}}coulombs\] positive charge. The conductor has (Charge on electron \[=1.6\times {{10}^{-19}}coulombs\])

Assertion : V-i characteristic of P-N junction diode is same as that of any other conductor. Reason : P-N junction diode behave as conductor at room temperature.

Assertion : The current gain in common base circuit is always less than one. Reason : At constant collector voltage the change in collector current is more than the change in emitter current.

Water rises upto 10 cm height in a long capillary tube. If this tube is immersed in water so that the height above the water surface is only 8 cm, then [MP PMT 1991]

The minimum charge on an object is

An electric current passes through a long straight wire. At a distance 5 cm from the wire, The magnetic field is B. The field at 20 cm from the wire would be [CPMT 2001; Pb PET 2002]

An electron is revolving round a proton, producing a magnetic field of 16 weber/m2 in a circular orbit of radius 1Å. It?s angular velocity will be [RPMT 2002]

Two protons A and B are placed in space between plates of a parallel plate capacitor charged upto V volts (See fig.) Forces on protons are \[{{F}_{A}}\] and \[{{F}_{B}}\], then [RPET 1999]

In transformer, core is made of soft iron to reduce [AIIMS 1998; UPSEAT 2001; AFMC 2005]

A long straight wire carrying current of 30A is placed in an external uniform magnetic field of induction 4 ´ 10?4T. The magnetic field is acting parallel to the direction of current. The magnitude of the resultant magnetic induction in tesla at a point 2.0 cm away from the wire is [EAMCET 2003]

Quantity that remains unchanged in a transformer is [MP PMT/PET 1998; AIIMS 1999; J & K CET 2005]

A parallel plate air capacitor is charged and then isolated. When a dielectric material is inserted between the plates of the capacitor, then which of the following does not change [Orissa JEE 2003]