12583 + Mcqs in Physics Page 26 McqOptions

1251.	The temperature on Celsius scale is \[25{}^\circ C\]. What is the corresponding temperature on the Fahrenheit scale
A.	\[40{}^\circ F\]
B.	\[77{}^\circ F\]
C.	\[50{}^\circ F\]
D.	\[45{}^\circ F\]
Answer» C. \[50{}^\circ F\]

Discussion

1252.	What will be the wave velocity, if the radar gives 54 waves per min and wavelength of the given wave is 10 m [RPET 2000]
A.	4 m/sec
B.	6 m/sec
C.	9 m/sec
D.	5 m/sec
Answer» D. 5 m/sec

Discussion

1253.	A hollow smooth uniform sphere A of mass m rolls without sliding on a smooth horizontal surface. It collides head on elastically with another stationary smooth solid sphere B of the same mass m and same radius. The ratio of kinetic energy of B to that of A just after the collision is
A.	0.0423611111111111
B.	0.0854166666666667
C.	0.126388888888889
D.	None of these
Answer» D. None of these

Discussion

1254.	Assertion : Electron has higher mobility than hole in a semiconductor. Reason : Mass of electron is less than the mass of hole.
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

1255.	Assertion : An N-type semiconductor has a large number of electrons but still it is electrically neutral. Reason : An N-type semiconductor is obtained by doping an intrinsic semiconductor with a pentavalent impurity.
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

1256.	Assertion : The crystalline solids have a sharp melting point. Reason : All the bonds between the atoms or molecules of a crystalline solids are equally strong, that they get broken at the same 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» B. If both assertion and reason are true but reason is not the correct explanation of the assertion.

Discussion

1257.	A body is thrown horizontally from the top of a tower of height 5 m. It touches the ground at a distance of 10 m from the foot of the tower. The initial velocity of the body is \[\left( g=10m{{s}^{2}} \right)\]
A.	\[2.5m{{s}^{1}}\]
B.	\[5m{{s}^{1}}\]
C.	\[10m{{s}^{1}}\]
D.	\[20m{{s}^{1}}\]
Answer» D. \[20m{{s}^{1}}\]

Discussion

1258.	When 100 volt dc is applied across a coil, a current of 1 amp flows through it. When 100 volt ac at 50 cycle\[{{s}^{-1}}\] is applied to the same coil, only 0.5 ampere current flows. The impedance of the coil is [Bihar MEE 1995]
A.	\[100\,\Omega \]
B.	\[200\,\Omega \]
C.	\[300\,\Omega \]
D.	\[400\,\Omega \]
Answer» C. \[300\,\Omega \]

Discussion

1259.	When a copper ball is heated, the largest percentage increase will occur in its [EAMCET 1992]
A.	Diameter
B.	Area
C.	Volume
D.	Density
Answer» D. Density

Discussion

1260.	A point object ?O? is at the center of curvature of a concave mirror. The mirror starts to move at a speed u, in a direction perpendicular to the principal axis. Then, the initial velocity of the image is
A.	2u, in the direction opposite to that of mirror's velocity
B.	2u, in the direction same as that of mirror's velocity
C.	zero
D.	u, in the direction same as that of mirror's velocity
Answer» C. zero

Discussion

1261.	In the following atoms and moleculates for the transition from n= 2 to n = 1, the spectral line of minimum wavelength will be produced by [IIT 1983]
A.	Hydrogen atom
B.	Deuterium atom
C.	Uni-ionized helium
D.	di-ionized lithium
Answer» E.

Discussion

1262.	Assertion : If the angles of the base of the prism are equal, then in the position of minimum deviation, the refracted ray will pass parallel to the base of prism. Reason : In the case of minimum deviation, the angle of incidence is equal to the angle of emergence.
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

1263.	Assertion : Dispersion of light occurs because velocity of light in a material depends upon its colour. Reason : The dispersive power depends only upon the material of the prism, not upon the refracting angle of the prism.
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

1264.	Assertion : An empty test tube dipped into water in a beaker appears silver, when viewed from a suitable direction. Reason : Due to refraction of light, the substance in water appears silvery.
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

1265.	Two coherent monochromatic light beams of intensities I and 4I are superposed. The maximum and minimum possible intensities in the resulting beam are [IIT-JEE 1988; RPMT 1995; AIIMS 1997; MP PMT 1997;MP PET 1999; BHU 2002; KCET 2000, 05]
A.	5I and I
B.	5I and 3I
C.	9I and I
D.	9I and 3I
Answer» D. 9I and 3I

Discussion

1266.	Light appears to travel in straight lines since [RPMT 1997; CPMT 1987, 89, 90, 2001; AIIMS 1998, 2002; KCET 2002; BHU 2002; DCE 2003]
A.	It is not absorbed by the atmosphere
B.	It is reflected by the atmosphere
C.	Its wavelength is very small
D.	Its velocity is very large
Answer» D. Its velocity is very large

Discussion

1267.	The idea of secondary wavelets for the propagation of a wave was first given by [Orissa PMT 2004]
A.	Newton
B.	Huygen
C.	Maxwell
D.	Fresnel
Answer» C. Maxwell

Discussion

1268.	The wavelength of the matter wave is independent of
A.	Mass
B.	Velocity
C.	Momentum
D.	Charge
Answer» E.

Discussion

1269.	The wavelength associated with an electron accelerated through a potential difference of 100 V is nearly
A.	100 \[\overset{\text{o}}{\mathop{\text{A}}}\,\]
B.	123 \[\overset{\text{o}}{\mathop{\text{A}}}\,\]
C.	1.23 \[\overset{\text{o}}{\mathop{\text{A}}}\,\]
D.	0.123 \[\overset{\text{o}}{\mathop{\text{A}}}\,\]
Answer» D. 0.123 \[\overset{\text{o}}{\mathop{\text{A}}}\,\]

Discussion

1270.	In a full wave rectifiers, input ac current has a frequency ?n?. The output frequency of current is [BHU 2005]
A.	n/2
B.	n
C.	2n
D.	None of these
Answer» D. None of these

Discussion

1271.	According to classical theory, the circular path of an electron in Rutherford atom is [BHU 2001]
A.	Spiral
B.	Circular
C.	Parabolic
D.	Straight line
Answer» B. Circular

Discussion

1272.	A simple pendulum executing S.H.M. is falling freely along with the support. Then
A.	Its periodic time decreases
B.	Its periodic time increases
C.	It does not oscillate at all
D.	None of these
Answer» D. None of these

Discussion

1273.	A pendulum bob has a speed of 3 m/s at its lowest position. The pendulum is 0.5 m long. The speed of the bob, when the length makes an angle of \[{{60}^{o}}\] to the vertical, will be (If \[g=10m/{{s}^{2}}\]) [MP PET 1996]
A.	\[\frac{E}{4}\]
B.	\[\frac{3E}{4}\]
C.	\[\frac{\sqrt{3}}{4}E\]
D.	\[{{K}_{1}}\]
Answer» E.

Discussion

1274.	The bob of a pendulum of length l is pulled aside from its equilibrium position through an angle \[\theta \] and then released. The bob will then pass through its equilibrium position with a speed v, where v equals [Haryana CEE 1996]
A.	\[U=K{{X}^{2}}\]
B.	\[\sqrt{2gl(1+\cos \theta )}\]
C.	\[U=KX\]
D.	\[\frac{a}{2}\]
Answer» D. \[\frac{a}{2}\]

Discussion

1275.	The potential energy between two atoms in a molecule is given by \[U(x)=\frac{a}{{{x}^{12}}}-\frac{b}{{{x}^{6}}}\]; where a and b are positive constants and x is the distance between the atoms. The atom is in stable equilibrium when [CBSE PMT 1995]
A.	\[x=\sqrt[6]{\frac{11a}{5b}}\]
B.	\[x=\sqrt[6]{\frac{a}{2b}}\]
C.	\[x=0\]
D.	\[x=\sqrt[6]{\frac{2a}{b}}\]
Answer» E.

Discussion

1276.	A block of mass 0.50 kg is moving with a speed of \[2.00\text{ }m{{s}^{-1}}\] on a smooth surface. It strikes another mass of 1.00 kg and then they move together as a single body. The energy loss during the collision is
A.	0.16 J
B.	1.00 J
C.	0.67 J
D.	0.34 J
Answer» D. 0.34 J

Discussion

1277.	Assertion : The equivalent thermal conductivity of two plates of same thickness in contact (series) is less than the smaller value of thermal conductivity. Reason : For two plates of equal thickness in contact (series) the equivalent thermal conductivity is given by [AIIMS 1997] \[\frac{1}{K}=\frac{1}{{{K}_{1}}}+\frac{1}{{{K}_{2}}}\]
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

1278.	A 20 kg block is initially at rest on a rough horizontal surface. A horizontal force of 75 N is required to set the block in motion. After it is in motion, a horizontal force of 60 N is required to keep the block moving with constant speed. The coefficient of static friction is [AMU 1999]
A.	0.38
B.	0.44
C.	0.52
D.	0.60
Answer» B. 0.44

Discussion

1279.	A conducting sphere of radius 10cm is charged \[10\mu \,C\]. Another uncharged sphere of radius 20 cm is allowed to touch it for some time. After that if the sphere are separated, then surface density of charges, on the spheres will be in the ratio of [AIIMS 2002]
A.	1 : 4
B.	1 : 3
C.	2 : 1
D.	1 : 1
Answer» D. 1 : 1

Discussion

1280.	A body of mass 5kg is suspended by a spring balance on an inclined plane as shown in figure. The spring balance measure
A.	50 N
B.	25 N
C.	500 N
D.	10 N
Answer» C. 500 N

Discussion

1281.	Assertion : Radio waves can be polarised. Reason : Sound waves in air are longitudinal in nature. [AIIMS 1998]
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

1282.	Assertion : The earth without atmosphere would be inhospitably cold. Reason : All heat would escape in the absence of atmosphere. [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

1283.	If \[{{R}_{p}}=7K\Omega ,\,{{g}_{m}}=2.5\] millimho, then on increasing plate voltage by \[50V\], how much the grid voltage is changed so that plate current remains the same [RPET 1996]
A.	? 2.86 V
B.	? 4 V
C.	+ 4 V
D.	+ 2 V
Answer» B. ? 4 V

Discussion

1284.	Moment of inertia does not depend upon
A.	distribution of mass
B.	axis of rotation
C.	point of application of force
D.	None of these
Answer» D. None of these

Discussion

1285.	Speed of sound in mercury at a certain temperature is 1450 m/s. Given the density of mercury as 13.6 ´ 103 kg / m3, the bulk modulus for mercury is [JIPMER 2000]
A.	2.86 ´1010 N/m3
B.	3.86 ´1010 N/m3
C.	4.86 ´1010 N/m3
D.	5.86 ´1010 N/m3
Answer» B. 3.86 ´1010 N/m3

Discussion

1286.	A micro-wave and an ultrasonic sound wave have the same wavelength. Their frequencies are in the ratio (approximately) [Kerala (Engg.) 2002]
A.	106 : 1
B.	104 : 1
C.	102 : 1
D.	10 : 1
Answer» B. 104 : 1

Discussion

1287.	Two sound sources when sounded simultaneously produce four beats in 0.25 second. the difference in their frequencies must be [BCECE 2003]
A.	4
B.	8
C.	16
D.	1
Answer» D. 1

Discussion

1288.	Assertion : \[\vec{A}.\vec{B}=\vec{B}.\vec{A}\] Reason : Dot product of two vectors is commutative.
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

1289.	The equation \[\overrightarrow{\varphi \,}(x,\,t)=\overrightarrow{j\,}\sin \,\left( \frac{2\pi }{\lambda }v\,t \right)\cos \,\left( \frac{2\pi }{\lambda }x \right)\] represents [MNR 1994]
A.	Transverse progressive wave
B.	Longitudinal progressive wave
C.	Longitudinal stationary wave
D.	Transverse stationary wave
Answer» E.

Discussion

1290.	The temperature of a wire of length 1 metre and area of cross-section \[1\,c{{m}^{2}}\] is increased from 0°C to 100°C. If the rod is not allowed to increase in length, the force required will be \[(\alpha ={{10}^{-5}}/{}^\circ C\] and \[Y={{10}^{11}}\,N/{{m}^{2}})\] [NCERT 1976; CPMT 1982, 91]
A.	\[{{10}^{3}}N\]
B.	\[{{10}^{4}}N\]
C.	\[{{10}^{5}}N\]
D.	\[{{10}^{9}}N\]
Answer» C. \[{{10}^{5}}N\]

Discussion

1291.	Two coherent sources separated by distance d are radiating in phase having wavelength X. A detector moves in a big circle around the two sources in the plane of the two sources. The angular position n=4 interference maxima is given as
A.	\[{{\sin }^{-1}}\frac{n\lambda }{d}\]
B.	\[{{\cos }^{-1}}\frac{4\lambda }{d}\]
C.	\[{{\tan }^{-1}}\frac{d}{4\lambda }\]
D.	\[{{\cos }^{-1}}\frac{\lambda }{4d}\]
Answer» C. \[{{\tan }^{-1}}\frac{d}{4\lambda }\]

Discussion

1292.	In YSDE, both slits are covered by transparent slab. Upper slit is covered by slab of R.I. 1.5 and thickness t and lower is covered by R.I. \[\frac{4}{3}\] and thickness 2t, then central maxima
A.	shifts in +ve y-axis direction
B.	shifts in -ve y-axis direction
C.	remains at same position
D.	may shift in upward or downward depending upon wavelength of light
Answer» C. remains at same position

Discussion

1293.	The capacity of a parallel plate condenser is \[10\,\mu \,F\], when the distance between its plates is 8 cm. If the distance between the plates is reduced to 4 cm, then the capacity of this parallel plate condenser will be [CBSE PMT 2001]
A.	\[5\,\mu \,F\]
B.	\[10\,\mu \,F\]
C.	\[20\,\mu \,F\]
D.	\[40\,\mu \,F\]
Answer» D. \[40\,\mu \,F\]

Discussion

1294.	The binding energy of deuteron \[(_{1}^{2}H)\] is 1.15 A MeV per nucleon and an alpha particle \[(_{2}^{4}He)\]has a binding energy of 7.1 MeV per nucleon. Then in the reaction \[_{1}^{2}He+_{1}^{2}He\to _{2}^{2}He+Q\] the energy released Q is:
A.	5.95 MeV
B.	26.1 MeV
C.	23.8 MeV
D.	289.4 MeV
Answer» D. 289.4 MeV

Discussion

1295.	Three charges are placed at the vertices of an equilateral triangle of side ?a? as shown in the following figure. The force experienced by the charge placed at the vertex A in a direction normal to BC is [AIIMS 2003]
A.	\[{{Q}^{2}}/(4\pi {{\varepsilon }_{0}}{{a}^{2}})\]
B.	\[-{{Q}^{2}}/(4\pi {{\varepsilon }_{0}}{{a}^{2}})\]
C.	Zero
D.	\[{{Q}^{2}}/(2\pi {{\varepsilon }_{0}}{{a}^{2}})\]
Answer» D. \[{{Q}^{2}}/(2\pi {{\varepsilon }_{0}}{{a}^{2}})\]

Discussion

1296.	A car travels north with a uniform velocity. It goes over a piece of mud which sticks to the tyre. The particles of the mud, as it leaves the ground are thrown
A.	Vertically upwards
B.	Vertically inwards
C.	Towards north
D.	Towards south
Answer» E.

Discussion

1297.	The capacity of a parallel plate condenser is \[15\mu \,F\], when the distance between its plates is 6 cm. If the distance between the plates is reduced to 2 cm, then the capacity of this parallel plate condenser will be [AFMC 2000]
A.	\[15\mu \,F\]
B.	\[30\mu \,F\]
C.	\[45\mu \,F\]
D.	\[60\mu \,F\]
Answer» D. \[60\mu \,F\]

Discussion

1298.	A block weighs W is held against a vertical wall by applying a horizontal force F. The minimum value of F needed to hold the block is [MP PMT 1993]
A.	Less than W
B.	Equal to W
C.	Greater than W
D.	Data is insufficient
Answer» D. Data is insufficient

Discussion

1299.	The cut-in voltage for silicon diode is approximately
A.	0.2 V
B.	0.6 V
C.	1.1 V
D.	1.4 V
Answer» C. 1.1 V

Discussion

1300.	A wire of length L and radius r is rigidly fixed at one end. On stretching the other end of the wire with a force F, the increase in its length is l. If another wire of same material but of length 2L and radius 2r is stretched with a force of 2F, the increase in its length will be [NCERT 1980; AIIMS 1980; MP PET 1989, 92; MP PET/PMT 1988; MP PMT 1996, 2002; UPSEAT 2002]
A.	l
B.	2l
C.	\[\frac{l}{2}\]
D.	\[\frac{l}{4}\]
Answer» B. 2l

Discussion

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

The temperature on Celsius scale is \[25{}^\circ C\]. What is the corresponding temperature on the Fahrenheit scale

What will be the wave velocity, if the radar gives 54 waves per min and wavelength of the given wave is 10 m [RPET 2000]

A hollow smooth uniform sphere A of mass m rolls without sliding on a smooth horizontal surface. It collides head on elastically with another stationary smooth solid sphere B of the same mass m and same radius. The ratio of kinetic energy of B to that of A just after the collision is

Assertion : Electron has higher mobility than hole in a semiconductor. Reason : Mass of electron is less than the mass of hole.

Assertion : An N-type semiconductor has a large number of electrons but still it is electrically neutral. Reason : An N-type semiconductor is obtained by doping an intrinsic semiconductor with a pentavalent impurity.

Assertion : The crystalline solids have a sharp melting point. Reason : All the bonds between the atoms or molecules of a crystalline solids are equally strong, that they get broken at the same temperature.

A body is thrown horizontally from the top of a tower of height 5 m. It touches the ground at a distance of 10 m from the foot of the tower. The initial velocity of the body is \[\left( g=10m{{s}^{2}} \right)\]

When 100 volt dc is applied across a coil, a current of 1 amp flows through it. When 100 volt ac at 50 cycle\[{{s}^{-1}}\] is applied to the same coil, only 0.5 ampere current flows. The impedance of the coil is [Bihar MEE 1995]

When a copper ball is heated, the largest percentage increase will occur in its [EAMCET 1992]

A point object ?O? is at the center of curvature of a concave mirror. The mirror starts to move at a speed u, in a direction perpendicular to the principal axis. Then, the initial velocity of the image is

In the following atoms and moleculates for the transition from n= 2 to n = 1, the spectral line of minimum wavelength will be produced by [IIT 1983]

Assertion : If the angles of the base of the prism are equal, then in the position of minimum deviation, the refracted ray will pass parallel to the base of prism. Reason : In the case of minimum deviation, the angle of incidence is equal to the angle of emergence.

Assertion : Dispersion of light occurs because velocity of light in a material depends upon its colour. Reason : The dispersive power depends only upon the material of the prism, not upon the refracting angle of the prism.

Assertion : An empty test tube dipped into water in a beaker appears silver, when viewed from a suitable direction. Reason : Due to refraction of light, the substance in water appears silvery.

Two coherent monochromatic light beams of intensities I and 4I are superposed. The maximum and minimum possible intensities in the resulting beam are [IIT-JEE 1988; RPMT 1995; AIIMS 1997; MP PMT 1997;MP PET 1999; BHU 2002; KCET 2000, 05]

Light appears to travel in straight lines since [RPMT 1997; CPMT 1987, 89, 90, 2001; AIIMS 1998, 2002; KCET 2002; BHU 2002; DCE 2003]

The idea of secondary wavelets for the propagation of a wave was first given by [Orissa PMT 2004]

The wavelength of the matter wave is independent of

The wavelength associated with an electron accelerated through a potential difference of 100 V is nearly

In a full wave rectifiers, input ac current has a frequency ?n?. The output frequency of current is [BHU 2005]

According to classical theory, the circular path of an electron in Rutherford atom is [BHU 2001]

A simple pendulum executing S.H.M. is falling freely along with the support. Then

A pendulum bob has a speed of 3 m/s at its lowest position. The pendulum is 0.5 m long. The speed of the bob, when the length makes an angle of \[{{60}^{o}}\] to the vertical, will be (If \[g=10m/{{s}^{2}}\]) [MP PET 1996]

The bob of a pendulum of length l is pulled aside from its equilibrium position through an angle \[\theta \] and then released. The bob will then pass through its equilibrium position with a speed v, where v equals [Haryana CEE 1996]

The potential energy between two atoms in a molecule is given by \[U(x)=\frac{a}{{{x}^{12}}}-\frac{b}{{{x}^{6}}}\]; where a and b are positive constants and x is the distance between the atoms. The atom is in stable equilibrium when [CBSE PMT 1995]

A block of mass 0.50 kg is moving with a speed of \[2.00\text{ }m{{s}^{-1}}\] on a smooth surface. It strikes another mass of 1.00 kg and then they move together as a single body. The energy loss during the collision is

A 20 kg block is initially at rest on a rough horizontal surface. A horizontal force of 75 N is required to set the block in motion. After it is in motion, a horizontal force of 60 N is required to keep the block moving with constant speed. The coefficient of static friction is [AMU 1999]

A conducting sphere of radius 10cm is charged \[10\mu \,C\]. Another uncharged sphere of radius 20 cm is allowed to touch it for some time. After that if the sphere are separated, then surface density of charges, on the spheres will be in the ratio of [AIIMS 2002]

A body of mass 5kg is suspended by a spring balance on an inclined plane as shown in figure. The spring balance measure

Assertion : Radio waves can be polarised. Reason : Sound waves in air are longitudinal in nature. [AIIMS 1998]

Assertion : The earth without atmosphere would be inhospitably cold. Reason : All heat would escape in the absence of atmosphere. [AIIMS 2002]

If \[{{R}_{p}}=7K\Omega ,\,{{g}_{m}}=2.5\] millimho, then on increasing plate voltage by \[50V\], how much the grid voltage is changed so that plate current remains the same [RPET 1996]

Moment of inertia does not depend upon

Speed of sound in mercury at a certain temperature is 1450 m/s. Given the density of mercury as 13.6 ´ 103 kg / m3, the bulk modulus for mercury is [JIPMER 2000]

A micro-wave and an ultrasonic sound wave have the same wavelength. Their frequencies are in the ratio (approximately) [Kerala (Engg.) 2002]

Two sound sources when sounded simultaneously produce four beats in 0.25 second. the difference in their frequencies must be [BCECE 2003]

Assertion : \[\vec{A}.\vec{B}=\vec{B}.\vec{A}\] Reason : Dot product of two vectors is commutative.

The equation \[\overrightarrow{\varphi \,}(x,\,t)=\overrightarrow{j\,}\sin \,\left( \frac{2\pi }{\lambda }v\,t \right)\cos \,\left( \frac{2\pi }{\lambda }x \right)\] represents [MNR 1994]

The temperature of a wire of length 1 metre and area of cross-section \[1\,c{{m}^{2}}\] is increased from 0°C to 100°C. If the rod is not allowed to increase in length, the force required will be \[(\alpha ={{10}^{-5}}/{}^\circ C\] and \[Y={{10}^{11}}\,N/{{m}^{2}})\] [NCERT 1976; CPMT 1982, 91]

Two coherent sources separated by distance d are radiating in phase having wavelength X. A detector moves in a big circle around the two sources in the plane of the two sources. The angular position n=4 interference maxima is given as

In YSDE, both slits are covered by transparent slab. Upper slit is covered by slab of R.I. 1.5 and thickness t and lower is covered by R.I. \[\frac{4}{3}\] and thickness 2t, then central maxima

The capacity of a parallel plate condenser is \[10\,\mu \,F\], when the distance between its plates is 8 cm. If the distance between the plates is reduced to 4 cm, then the capacity of this parallel plate condenser will be [CBSE PMT 2001]

The binding energy of deuteron \[(_{1}^{2}H)\] is 1.15 A MeV per nucleon and an alpha particle \[(_{2}^{4}He)\]has a binding energy of 7.1 MeV per nucleon. Then in the reaction \[_{1}^{2}He+_{1}^{2}He\to _{2}^{2}He+Q\] the energy released Q is:

Three charges are placed at the vertices of an equilateral triangle of side ?a? as shown in the following figure. The force experienced by the charge placed at the vertex A in a direction normal to BC is [AIIMS 2003]

A car travels north with a uniform velocity. It goes over a piece of mud which sticks to the tyre. The particles of the mud, as it leaves the ground are thrown

The capacity of a parallel plate condenser is \[15\mu \,F\], when the distance between its plates is 6 cm. If the distance between the plates is reduced to 2 cm, then the capacity of this parallel plate condenser will be [AFMC 2000]

A block weighs W is held against a vertical wall by applying a horizontal force F. The minimum value of F needed to hold the block is [MP PMT 1993]

The cut-in voltage for silicon diode is approximately