12583 + Mcqs in Physics Page 181 McqOptions

9001.	In a step-up transformer the voltage in the primary is 220 V and the current is 5A. The secondary voltage is found to be 22000V. The current in the secondary (neglect losses) is [Kerala PMT 2002]
A.	5 A
B.	50 A
C.	500 A
D.	0.05 A
Answer» E.

Discussion

9002.	Assertion : The position-time graph of a uniform motion in one dimension of a body can have negative slope. Reason : When the speed of body decreases with time, the position-time graph of the moving body has negative slope.
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

9003.	An infinitely long straight conductor is bent into the shape as shown in the figure. It carries a current of i ampere and the radius of the circular loop is r metre. Then the magnetic induction at its centre will be [MP PMT 1999]
A.	\[\frac{{{\mu }_{0}}}{4\pi }\frac{2i}{r}(\pi +1)\]
B.	\[\frac{{{\mu }_{0}}}{4\pi }\frac{2i}{r}(\pi -1)\]
C.	Zero
D.	Infinite
Answer» C. Zero

Discussion

9004.	Assertion : When a body is dropped or thrown horizontally from the same height, it would reach the ground at the same time. Reason : Horizontal velocity has no effect on the vertical direction.
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

9005.	A player caught a cricket ball of mass 150 gm moving at a rate of 20 m/s. If the catching process be completed in 0.1 s, then the force of the blow exerted by the ball on the hands of the player is [AFMC 1993; CBSE PMT 2001; BHU 2001]
A.	0.3 N
B.	30 N
C.	300 N
D.	3000 N
Answer» C. 300 N

Discussion

9006.	Work done in raising a box depends on
A.	How fast it is raised
B.	The strength of the man
C.	The height by which it is raised
D.	None of the above
Answer» D. None of the above

Discussion

9007.	The angular velocity of the earth with which it has to rotate so that acceleration due to gravity on 60o latitude becomes zero is (Radius of earth = 6400 km. At the poles \[g=10\,m{{s}^{-2}})\] [EAMCET 2000]
A.	\[2.5\times {{10}^{-3}}rad/s\]
B.	\[5.0\times {{10}^{-1}}rad/s\]
C.	\[10\times {{10}^{1}}rad/s\]
D.	\[7.8\times {{10}^{-2}}rad/s\]
Answer» B. \[5.0\times {{10}^{-1}}rad/s\]

Discussion

9008.	Assertion : Even when orbit of a satellite is elliptical, its plane of rotation passes through the centre of earth. Reason : According to law of conservation of angular momentum plane of rotation of satellite always remain same.
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

9009.	A monoatomic gas \[(\gamma =5/3)\] is suddenly compressed to \[\frac{1}{8}\] of its original volume adiabatically, then the pressure of the gas will change to [CPMT 1976, 83; MP PMT 1994; DPMT 1996; Roorkee 2000; KCET 2000; Pb. PMT 1999, 2001]
A.	\[\frac{24}{5}\]
B.	8
C.	\[\frac{40}{3}\]
D.	32 times its initial pressure
Answer» E.

Discussion

9010.	What should be the current in a circular coil of radius 5cm to annul \[{{B}_{H}}=5\times {{10}^{-5}}T\] [DCE 2001]
A.	0.4 A
B.	4 A
C.	40 A
D.	1 A
Answer» C. 40 A

Discussion

9011.	Assertion : Vector addition is commutative. Reason : \[(\vec{A}+\vec{B})\ne (\vec{B}+\vec{A}).\]
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

9012.	Assertion : A loosely round helix made of stiff wire is suspended vertically with the lower end just touching a dish of mercury. When a current is passed through the wire, the helical wire executes oscillatory motion with the lower end jumping out of and inside of mercury. Reason : When electric current is passed through helix, a magnetic field is produced both inside and outside the helix.
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

9013.	A capacitor is kept connected to the battery and a dielectric slab is inserted between the plates. During this process [MP PMT 1994]
A.	No work is done
B.	Work is done at the cost of the energy already stored in the capacitor before the slab is inserted
C.	Work is done at the cost of the battery
D.	Work is done at the cost of both the capacitor and the battery
Answer» D. Work is done at the cost of both the capacitor and the battery

Discussion

9014.	The disc of a siren containing 60 holes rotates at a constant speed of 360 rpm. The emitted sound is in unison with a tuning fork of frequency [KCET 2005]
A.	10 Hz
B.	360 Hz
C.	216 Hz
D.	6 Hz
Answer» C. 216 Hz

Discussion

9015.	In a hydrogen atom, an electron moves in a circular orbit of radius \[5.2\times {{10}^{-11}}\,m\] and produces a magnetic induction of 12.56 T at its nucleus. The current produced by the motion of the electron will be (Given \[{{\mu }_{0}}=4\pi \times {{10}^{-7}}\,Wb/A-m)\] [MP PET 1997]
A.	\[6.53\times {{10}^{-3}}\,ampere\]
B.	\[13.25\times {{10}^{-10}}\,ampere\]
C.	\[9.6\times {{10}^{6}}\,ampere\]
D.	\[1.04\times {{10}^{-3}}\,ampere\]
Answer» E.

Discussion

9016.	A tuning fork makes 256 vibrations per second in air. When the velocity of sound is 330 m/s, then wavelength of the tone emitted is [KCET 1994; AFMC 1998; MH CET 1999; CBSE PMT 1999]
A.	0.56 m
B.	0.89 m
C.	1.11 m
D.	1.29 m
Answer» E.

Discussion

9017.	An underwater sonar source operating at a frequency of 60 KHz directs its beam towards the surface. If the velocity of sound in air is 330 m/s, the wavelength and frequency of waves in air are: [DPMT 2004]
A.	5.5 mm, 60 KHz
B.	330 m, 60 KHz
C.	5.5 mm, 20 KHz
D.	5.5 mm, 80 KHz
Answer» B. 330 m, 60 KHz

Discussion

9018.	The strength of the magnetic field at a point r near a long straight current carrying wire is B. The field at a distance \[\frac{r}{2}\] will be [MP PMT 1990]
A.	\[\frac{B}{2}\]
B.	\[\frac{B}{4}\]
C.	2B
D.	4B
Answer» D. 4B

Discussion

9019.	A step index fibre has a relative refractive index of 0.88%. What is the critical angle at the corecladding interface [Manipal 2003]
A.	60°
B.	75°
C.	45°
D.	None of these
Answer» E.

Discussion

9020.	Assertion : Sound would travel faster on a hot summer day than on a cold winter day. Reason : Velocity of sound is directly proportional to the square of its absolute 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» D. If the assertion and reason both are false.

Discussion

9021.	Assertion : The basic of Laplace correction was that, exchange of heat between the region of compression and rarefaction in air is not possible. Reason : Air is a bad conductor of heat and velocity of sound in air is large.
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

9022.	Assertion : A body, whatever its motion is always at rest in a frame of reference which is fixed to the body itself. Reason : The relative velocity of a body with respect to itself is zero.
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

9023.	Assertion : An electric motor will maximum efficient when back e.m.f. is equal to applied e.m.f. Reason : Efficiency of electric motor is depends only on magnitude of back e.m.f..
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

9024.	Assertion : The threshold frequency of photoelectric effect supports the particle nature of sunlight. Reason : If frequency of incident light is less than the threshold frequency, electrons are not emitted from metal surface.
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

9025.	In an induction coil with resistance, the induced emf will be maximum when [RPMT 1996]
A.	The switch is put on due to high resistance
B.	The switch is put off due to high resistance
C.	The switch is put on due to low resistance
D.	The switch is put off due to low resistance
Answer» C. The switch is put on due to low resistance

Discussion

9026.	A ball falling in a lake of depth 200 m shows 0.1% decrease in its volume at the bottom. What is the bulk modulus of the material of the ball [AFMC 1997]
A.	\[19.6\times {{10}^{8}}\,N/{{m}^{2}}\]
B.	\[19.6\times {{10}^{-10}}\,N/{{m}^{2}}\]
C.	\[19.6\times {{10}^{10}}\,N/{{m}^{2}}\]
D.	\[19.6\times {{10}^{-8}}\,N/{{m}^{2}}\]
Answer» B. \[19.6\times {{10}^{-10}}\,N/{{m}^{2}}\]

Discussion

9027.	Assertion : An induced emf is generated when magnet is withdrawn from the solenoid. Reason : The relative motion between magnet and solenoid induces emf.
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

9028.	Assertion : A narrow pulse of light is sent through a medium. The pulse will retain its shape as it travels through the medium. Reason : A narrow pulse is made of harmonic waves with a large range of wavelengths.
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

9029.	Assertion : When a light wave travels from a rarer to a denser medium, it loses speed. The reduction in speed imply a reduction in energy carried by the light wave. Reason : The energy of a wave is proportional to velocity of wave.
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

9030.	Dynamo core is laminated because [MP PET 1995]
A.	Magnetic field increases
B.	Magnetic saturation level in core increases
C.	Residual magnetism in core decreases
D.	Loss of energy in core due to eddy currents decreases
Answer» E.

Discussion

9031.	Assertion : Fax is a modulating and demodulating device. Reason : It is necessary for exact reproduction of a document.
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

9032.	The minimum audible wavelength at room temperature is about [AFMC 1996]
A.	0.2 Å
B.	5 Å
C.	5 cm to 2 metre
D.	20 mm
Answer» E.

Discussion

9033.	The earth's magnetic induction at a certain point is \[7\times {{10}^{-5}}Wb/{{m}^{2}}.\] This is to be annulled by the magnetic induction at the centre of a circular conducting loop of radius 5 cm. The required current in the loop is [MP PET 1999; MP PMT 2002]
A.	0.56 A
B.	5.6 A
C.	0.28 A
D.	2.8 A
Answer» C. 0.28 A

Discussion

9034.	Assertion : Vector addition of two vectors \[\vec{A}\] and \[\vec{B}\] is commutative. Reason : \[\vec{A}+\vec{B}=\vec{B}+\vec{A}\]
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

9035.	The potentials of the two plates of capacitor are +10V and ?10 V. The charge on one of the plates is 40 C. The capacitance of the capacitor is [AFMC 2005]
A.	2 F
B.	4 F
C.	0.5 F
D.	0.25 F
Answer» B. 4 F

Discussion

9036.	Assertion : Gravitational force between two particles is negligibly small compared to the electrical force. Reason : The electrical force is experienced by charged particles only.
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

9037.	Two bodies of masses m and 2m have same momentum. Their respective kinetic energies \[{{E}_{1}}\] and \[{{E}_{2}}\] are in the ratio [MP PET 1997; KCET 2004]
A.	1 : 2
B.	2 : 1
C.	\[1:\sqrt{2}\]
D.	1 : 4
Answer» C. \[1:\sqrt{2}\]

Discussion

9038.	Assertion : The mirrors used in search lights are parabolic and not concave spherical. Reason : In a concave spherical mirror the image formed is always virtual.
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

9039.	Assertion : The size of the mirror affect the nature of the image. Reason : Small mirrors always forms a virtual image.
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

9040.	A beaker contains 200 gm of water. The heat capacity of the beaker is equal to that of 20 gm of water. The initial temperature of water in the beaker is 20°C. If 440 gm of hot water at 92°C is poured in it, the final temperature (neglecting radiation loss) will be nearest to [NSEP 1994]
A.	58°C
B.	68°C
C.	73°C
D.	78°C
Answer» C. 73°C

Discussion

9041.	During constant temperature, we feel colder on a day when the relative humidity will be [Pb. PMT 1996]
A.	25%
B.	12.5%
C.	50%
D.	75%
Answer» B. 12.5%

Discussion

9042.	The time of revolution of an electron around a nucleus of charge Ze in nth Bohr orbit is directly proportional to [MP PET 2003]
A.	n
B.	\[\frac{{{n}^{3}}}{{{Z}^{2}}}\]
C.	\[\frac{{{n}^{2}}}{Z}\]
D.	\[\frac{Z}{n}\]
Answer» C. \[\frac{{{n}^{2}}}{Z}\]

Discussion

9043.	Energy E of a hydrogen atom with principal quantum number n is given by \[E=\frac{-13.6}{{{n}^{2}}}eV\]. The energy of a photon ejected when the electron jumps from \[n=3\] state to \[n=2\] state of hydrogen is approximately [CBSE PMT 2004]
A.	1.5 eV
B.	0.85 eV
C.	3.4 eV
D.	1.9 eV
Answer» E.

Discussion

9044.	The sum of two forces acting at a point is 16 N. If the resultant force is 8 N and its direction is perpendicular to minimum force then the forces are [CPMT 1997]
A.	6 N and 10 N
B.	8 N and 8 N
C.	4 N and 12 N
D.	2 N and 14 N
Answer» B. 8 N and 8 N

Discussion

9045.	A charge of \[{{10}^{-9}}C\] is placed on each of the 64 identical drops of radius \[2cm\]. They are then combined to form a bigger drop. Find its potential [MP PET 1997]
A.	\[7.2\times {{10}^{3}}V\]
B.	\[7.2\times {{10}^{2}}V\]
C.	\[1.44\times {{10}^{2}}V\]
D.	\[1.44\times {{10}^{3}}V\]
Answer» B. \[7.2\times {{10}^{2}}V\]

Discussion

9046.	Unit of magnetic permeability is [AFMC 2002]
A.	Amp/metre
B.	Amp/\[{{m}^{2}}\]
C.	Henry
D.	Henry/metre
Answer» E.

Discussion

9047.	Assertion : Impulse and momentum have different dimensions. Reason : From Newton?s second law of motion, impulse is equal to change in 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» F.

Discussion

9048.	Which of the following transition will have highest emission wavelength [BHU 2003]
A.	\[n=2\text{ to} n=1\]
B.	\[n=1\text{ to }n=2\]
C.	\[n=2\text{ }\,\text{to}\,\,n=5\]
D.	\[n=5\text{ to }n=2\]
Answer» E.

Discussion

9049.	Assertion : The positively charged nucleus of an atom has a radius of almost \[{{10}^{-15}}m.\] Reason : In a-particle scattering experiment, the distance of closest approach for a-particles is ≃\[{{10}^{-15}}m.\]
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

9050.	The efficiency of transformer is very high because [MP PET 1994]
A.	There is no moving part in a transformer
B.	It produces very high voltage
C.	It produces very low voltage
D.	None of the above
Answer» B. It produces very high voltage

Discussion

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

In a step-up transformer the voltage in the primary is 220 V and the current is 5A. The secondary voltage is found to be 22000V. The current in the secondary (neglect losses) is [Kerala PMT 2002]

Assertion : The position-time graph of a uniform motion in one dimension of a body can have negative slope. Reason : When the speed of body decreases with time, the position-time graph of the moving body has negative slope.

An infinitely long straight conductor is bent into the shape as shown in the figure. It carries a current of i ampere and the radius of the circular loop is r metre. Then the magnetic induction at its centre will be [MP PMT 1999]

Assertion : When a body is dropped or thrown horizontally from the same height, it would reach the ground at the same time. Reason : Horizontal velocity has no effect on the vertical direction.

A player caught a cricket ball of mass 150 gm moving at a rate of 20 m/s. If the catching process be completed in 0.1 s, then the force of the blow exerted by the ball on the hands of the player is [AFMC 1993; CBSE PMT 2001; BHU 2001]

Work done in raising a box depends on

The angular velocity of the earth with which it has to rotate so that acceleration due to gravity on 60o latitude becomes zero is (Radius of earth = 6400 km. At the poles \[g=10\,m{{s}^{-2}})\] [EAMCET 2000]

Assertion : Even when orbit of a satellite is elliptical, its plane of rotation passes through the centre of earth. Reason : According to law of conservation of angular momentum plane of rotation of satellite always remain same.

A monoatomic gas \[(\gamma =5/3)\] is suddenly compressed to \[\frac{1}{8}\] of its original volume adiabatically, then the pressure of the gas will change to [CPMT 1976, 83; MP PMT 1994; DPMT 1996; Roorkee 2000; KCET 2000; Pb. PMT 1999, 2001]

What should be the current in a circular coil of radius 5cm to annul \[{{B}_{H}}=5\times {{10}^{-5}}T\] [DCE 2001]

Assertion : Vector addition is commutative. Reason : \[(\vec{A}+\vec{B})\ne (\vec{B}+\vec{A}).\]

A capacitor is kept connected to the battery and a dielectric slab is inserted between the plates. During this process [MP PMT 1994]

The disc of a siren containing 60 holes rotates at a constant speed of 360 rpm. The emitted sound is in unison with a tuning fork of frequency [KCET 2005]

In a hydrogen atom, an electron moves in a circular orbit of radius \[5.2\times {{10}^{-11}}\,m\] and produces a magnetic induction of 12.56 T at its nucleus. The current produced by the motion of the electron will be (Given \[{{\mu }_{0}}=4\pi \times {{10}^{-7}}\,Wb/A-m)\] [MP PET 1997]

A tuning fork makes 256 vibrations per second in air. When the velocity of sound is 330 m/s, then wavelength of the tone emitted is [KCET 1994; AFMC 1998; MH CET 1999; CBSE PMT 1999]

An underwater sonar source operating at a frequency of 60 KHz directs its beam towards the surface. If the velocity of sound in air is 330 m/s, the wavelength and frequency of waves in air are: [DPMT 2004]

The strength of the magnetic field at a point r near a long straight current carrying wire is B. The field at a distance \[\frac{r}{2}\] will be [MP PMT 1990]

A step index fibre has a relative refractive index of 0.88%. What is the critical angle at the corecladding interface [Manipal 2003]

Assertion : Sound would travel faster on a hot summer day than on a cold winter day. Reason : Velocity of sound is directly proportional to the square of its absolute temperature.

Assertion : The basic of Laplace correction was that, exchange of heat between the region of compression and rarefaction in air is not possible. Reason : Air is a bad conductor of heat and velocity of sound in air is large.

Assertion : A body, whatever its motion is always at rest in a frame of reference which is fixed to the body itself. Reason : The relative velocity of a body with respect to itself is zero.

Assertion : An electric motor will maximum efficient when back e.m.f. is equal to applied e.m.f. Reason : Efficiency of electric motor is depends only on magnitude of back e.m.f..

Assertion : The threshold frequency of photoelectric effect supports the particle nature of sunlight. Reason : If frequency of incident light is less than the threshold frequency, electrons are not emitted from metal surface.

In an induction coil with resistance, the induced emf will be maximum when [RPMT 1996]

A ball falling in a lake of depth 200 m shows 0.1% decrease in its volume at the bottom. What is the bulk modulus of the material of the ball [AFMC 1997]

Assertion : An induced emf is generated when magnet is withdrawn from the solenoid. Reason : The relative motion between magnet and solenoid induces emf.

Assertion : A narrow pulse of light is sent through a medium. The pulse will retain its shape as it travels through the medium. Reason : A narrow pulse is made of harmonic waves with a large range of wavelengths.

Assertion : When a light wave travels from a rarer to a denser medium, it loses speed. The reduction in speed imply a reduction in energy carried by the light wave. Reason : The energy of a wave is proportional to velocity of wave.

Dynamo core is laminated because [MP PET 1995]

Assertion : Fax is a modulating and demodulating device. Reason : It is necessary for exact reproduction of a document.

The minimum audible wavelength at room temperature is about [AFMC 1996]

The earth's magnetic induction at a certain point is \[7\times {{10}^{-5}}Wb/{{m}^{2}}.\] This is to be annulled by the magnetic induction at the centre of a circular conducting loop of radius 5 cm. The required current in the loop is [MP PET 1999; MP PMT 2002]

Assertion : Vector addition of two vectors \[\vec{A}\] and \[\vec{B}\] is commutative. Reason : \[\vec{A}+\vec{B}=\vec{B}+\vec{A}\]

The potentials of the two plates of capacitor are +10V and ?10 V. The charge on one of the plates is 40 C. The capacitance of the capacitor is [AFMC 2005]

Assertion : Gravitational force between two particles is negligibly small compared to the electrical force. Reason : The electrical force is experienced by charged particles only.

Two bodies of masses m and 2m have same momentum. Their respective kinetic energies \[{{E}_{1}}\] and \[{{E}_{2}}\] are in the ratio [MP PET 1997; KCET 2004]

Assertion : The mirrors used in search lights are parabolic and not concave spherical. Reason : In a concave spherical mirror the image formed is always virtual.

Assertion : The size of the mirror affect the nature of the image. Reason : Small mirrors always forms a virtual image.

A beaker contains 200 gm of water. The heat capacity of the beaker is equal to that of 20 gm of water. The initial temperature of water in the beaker is 20°C. If 440 gm of hot water at 92°C is poured in it, the final temperature (neglecting radiation loss) will be nearest to [NSEP 1994]

During constant temperature, we feel colder on a day when the relative humidity will be [Pb. PMT 1996]

The time of revolution of an electron around a nucleus of charge Ze in nth Bohr orbit is directly proportional to [MP PET 2003]

Energy E of a hydrogen atom with principal quantum number n is given by \[E=\frac{-13.6}{{{n}^{2}}}eV\]. The energy of a photon ejected when the electron jumps from \[n=3\] state to \[n=2\] state of hydrogen is approximately [CBSE PMT 2004]

The sum of two forces acting at a point is 16 N. If the resultant force is 8 N and its direction is perpendicular to minimum force then the forces are [CPMT 1997]

A charge of \[{{10}^{-9}}C\] is placed on each of the 64 identical drops of radius \[2cm\]. They are then combined to form a bigger drop. Find its potential [MP PET 1997]

Unit of magnetic permeability is [AFMC 2002]

Assertion : Impulse and momentum have different dimensions. Reason : From Newton?s second law of motion, impulse is equal to change in momentum.

Which of the following transition will have highest emission wavelength [BHU 2003]

Assertion : The positively charged nucleus of an atom has a radius of almost \[{{10}^{-15}}m.\] Reason : In a-particle scattering experiment, the distance of closest approach for a-particles is ≃\[{{10}^{-15}}m.\]

The efficiency of transformer is very high because [MP PET 1994]