12583 + Mcqs in Physics Page 201 McqOptions

10001.	The magnetic field \[d\overrightarrow{B}\] due to a small current element \[d\overrightarrow{l\,}\] at a distance \[\overrightarrow{r\,}\] and element carrying current i is, or Vector form of Biot-savart's law is [CBSE PMT 1996; MP PET 2002; MP PMT 2000]
A.	\[d\overrightarrow{B}=\frac{{{\mu }_{0}}}{4\pi }i\,\left( \frac{d\overrightarrow{l\,}\times \overrightarrow{r\,}}{r} \right)\]
B.	\[d\overrightarrow{B}=\frac{{{\mu }_{0}}}{4\pi }{{i}^{2}}\,\left( \frac{d\overrightarrow{l\,}\times \overrightarrow{r\,}}{r} \right)\]
C.	\[d\overrightarrow{B}=\frac{{{\mu }_{0}}}{4\pi }{{i}^{2}}\,\left( \frac{d\overrightarrow{l\,}\times \overrightarrow{r\,}}{{{r}^{2}}} \right)\]
D.	\[d\overrightarrow{B}=\frac{{{\mu }_{0}}}{4\pi }i\,\left( \frac{d\overrightarrow{l\,}\times \overrightarrow{r\,}}{{{r}^{3}}} \right)\]
Answer» E.

Discussion

10002.	Assertion : A block of wood is floating in a tank containing water. The apparent weight of the floating block is equal to zero. Reason : Because the entire weight of the block is supported by the buoyant force (the upward thrust) due to water.
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

10003.	An alternating voltage is represented as \[E=20\sin 300t.\] The average value of voltage over one cycle will be [MP PMT 2002]
A.	Zero
B.	10 volt
C.	\[20\sqrt{2}\] volt
D.	\[\frac{20}{\sqrt{2}}\] volt
Answer» B. 10 volt

Discussion

10004.	When the temperature is increased the angle of contact of a liquid [AIIMS 1980]
A.	Increases
B.	Decreases
C.	Remains the same
D.	First increases and then decreases
Answer» C. Remains the same

Discussion

10005.	What is the ratio of wavelength of radiations emitted when an electron in hydrogen atom jump from fourth orbit to second orbit and from third orbit to second orbit [MH CET 2004]
A.	27 : 25
B.	20 : 27
C.	20 : 25
D.	25 : 27
Answer» C. 20 : 25

Discussion

10006.	If the momentum of a body increases by 0.01%, its kinetic energy will increase by [MP PET 2001]
A.	0.01%
B.	0.02%
C.	0.04%
D.	0.08%
Answer» C. 0.04%

Discussion

10007.	Assertion : If the net external force on the body is zero, then its acceleration is zero. Reason : Acceleration does not depend on force.
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

10008.	Assertion : A domestic electrical appliance, working on a three pin will continue working even if the top pin is removed. [AIIMS 1995] Reason : The third pin is used only as a safety device.
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

10009.	At \[{{27}^{o}}C\] a gas is suddenly compressed such that its pressure becomes \[\frac{1}{8}th\] of original pressure. Temperature of the gas will be \[(\gamma =5/3)\] [BHU 2000]
A.	420K
B.	\[{{327}^{o}}C\]
C.	\[300K\]
D.	\[-{{142}^{o}}C\]
Answer» E.

Discussion

10010.	A bullet of mass 0.1 kg is fired with a speed of 100 m/sec, the mass of gun is 50 kg. The velocity of recoil is [AFMC 1995; JIPMER 2000; Pb.PMT 2002]
A.	0.2 m/sec
B.	0.1 m/sec
C.	0.5 m/sec
D.	0.05 m/sec
Answer» B. 0.1 m/sec

Discussion

10011.	Assertion : Water can be boiled inside satellite by convection. Reason : Convection is the process in which heat is transmitted from a place of higher temperature to a place of lower temperature by means of particles with their migrations from one place to another.
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

10012.	Cathode rays consist of [DCE 1999]
A.	Photons
B.	Electrons
C.	Protons
D.	\[\alpha \]-particles
Answer» C. Protons

Discussion

10013.	Two identical square rods of metal are welded end to end as shown in figure (i), 20 calories of heat flows through it in 4 minutes. If the rods are welded as shown in figure (ii), the same amount of heat will flow through the rods in [NCERT 1982]
A.	1 minute
B.	2 minutes
C.	4 minutes
D.	16 minutes
Answer» B. 2 minutes

Discussion

10014.	Wires A and B have identical lengths and have circular cross-sections. The radius of A is twice the radius of B \[i.e.\] \[{{r}_{A}}=2{{r}_{B}}\]. For a given temperature difference between the two ends, both wires conduct heat at the same rate. The relation between the thermal conductivities is given by
A.	\[{{K}_{A}}=4{{K}_{B}}\]
B.	\[{{K}_{A}}=2{{K}_{B}}\]
C.	\[{{K}_{A}}={{K}_{B}}/2\]
D.	\[{{K}_{A}}={{K}_{B}}/4\]
Answer» E.

Discussion

10015.	An ac generator produced an output voltage \[E=170\sin 377\,t\,volts\], where t is in seconds. The frequency of ac voltage is [MP PET 1994]
A.	50 Hz
B.	110 Hz
C.	60 Hz
D.	230 Hz
Answer» D. 230 Hz

Discussion

10016.	When work is done on a body by an external force, its
A.	Only kinetic energy increases
B.	Only potential energy increases
C.	Both kinetic and potential energies may increase
D.	Sum of kinetic and potential energies remains constant
Answer» D. Sum of kinetic and potential energies remains constant

Discussion

10017.	What should be the velocity of earth due to rotation about its own axis so that the weight at equator become 3/5 of initial value. Radius of earth on equator is 6400 km [AMU 1999]
A.	\[7.4\times {{10}^{-4}}\,rad/\sec \]
B.	\[6.7\times {{10}^{-4}}\,rad/\sec \]
C.	\[7.8\times {{10}^{-4}}\,rad/\sec \]
D.	\[8.7\times {{10}^{-4}}\,rad/\sec \]
Answer» D. \[8.7\times {{10}^{-4}}\,rad/\sec \]

Discussion

10018.	A parallel plate air capacitor is charged to a potential difference of V. After disconnecting the battery, distance between the plates of the capacitor is increased using an insulating handle. As a result, the potential difference between the plates [KCET 1999]
A.	Decreases
B.	Increases
C.	Becomes zero
D.	Does not change
Answer» C. Becomes zero

Discussion

10019.	Assertion : The isothermal curves intersect each other at a certain point. Reason : The isothermal change takes place slowly, so the isothermal curves have very little slope. [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» F.

Discussion

10020.	If the density of a small planet is the same as that of earth, while the radius of the planet is 0.2 times that of the earth, the gravitational acceleration on the surface of that planet is [UPSEAT 2004; CBSE PMT 2005]
A.	0.2 g
B.	0.4 g
C.	2 g
D.	4 g
Answer» B. 0.4 g

Discussion

10021.	A condenser of capacity \[50\,\mu F\]is charged to \[10\ volts\]. Its energy is equal to [CPMT 1978; MP PET 1994; MP PMT 2000]
A.	\[2.5\times {{10}^{-3}}\ joule\]
B.	\[2.5\times {{10}^{-4}}\ joule\]
C.	\[5\times {{10}^{-2}}\ joule\]
D.	\[1.2\times {{10}^{-8}}\ joule\]
Answer» B. \[2.5\times {{10}^{-4}}\ joule\]

Discussion

10022.	When \[{{10}^{14}}\] electrons are removed from a neutral metal sphere, the charge on the sphere becomes [Manipal JEE 1995]
A.	\[16\,\mu \,C\]
B.	\[-16\,\mu \,C\]
C.	\[32\,\mu \,C\]
D.	\[-32\,\mu \,C\]
Answer» B. \[-16\,\mu \,C\]

Discussion

10023.	Assertion : The amplitude of an oscillating pendulum decreases gradually with time Reason : The frequency of the pendulum decreases with time [AIIMS 2003]
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

10024.	Assertion : In S.H.M., the motion is ?to and fro? and periodic. Reason : Velocity of the particle \[(v)=\omega \sqrt{{{k}^{2}}-{{x}^{2}}}\] (where x is the displacement and k is amplitude) [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» C. If assertion is true but reason is false.

Discussion

10025.	Assertion : The surface wave propagation is used for medium wave band and for television broadcasting. Reason : The surface waves travel directly from transmitting antenna to receiver antenna through atmosphere.
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

10026.	Every series of hydrogen spectrum has an upper and lower limit in wavelength. The spectral series which has an upper limit of wavelength equal to 18752 Å is [MP PMT 1993]
A.	Balmer series
B.	Lyman series
C.	Paschen series
D.	Pfund series (Rydberg constant \[R=1.097\times {{10}^{7}}\]per metre)
Answer» D. Pfund series (Rydberg constant \[R=1.097\times {{10}^{7}}\]per metre)

Discussion

10027.	A transformer has turn ratio 100/1. If secondary coil has 4 amp current then current in primary coil is [RPET 2000]
A.	4 A
B.	0.04 A
C.	0.4 A
D.	400 A
Answer» C. 0.4 A

Discussion

10028.	Assertion : A direct current flows through a metallic rod, produced magnetic field only outside the rod. Reason : There is no flow of charge carriers inside the rod.
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

10029.	Assertion : In the phenomenon of mutual induction, self induction of each of the coils persists. Reason : Self induction arises when strength of current in same coil changes. In mutual induction, current is changing in both the individual coils.
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

10030.	A man is standing between two parallel cliffs and fires a gun. If he hears first and second echoes after 1.5 s and 3.5s respectively, the distance between the cliffs is (Velocity of sound in air = 340 ms?1) [EAMCET (Med.) 2000]
A.	1190 m
B.	850 m
C.	595 m
D.	510 m
Answer» C. 595 m

Discussion

10031.	Two monoatomic ideal gases 1 and 2 of molecular masses m1 and m2 respectively are enclosed in separate containers kept at the same temperature. The ratio of the speed of sound in gas 1 to that in gas 2 is given by [IIT-JEE Screening 2000]
A.	\[\sqrt{\frac{{{m}_{1}}}{{{m}_{2}}}}\]
B.	\[\sqrt{\frac{{{m}_{2}}}{{{m}_{1}}}}\]
C.	\[\frac{{{m}_{1}}}{{{m}_{2}}}\]
D.	\[\frac{{{m}_{2}}}{{{m}_{1}}}\]
Answer» C. \[\frac{{{m}_{1}}}{{{m}_{2}}}\]

Discussion

10032.	The energy levels of the hydrogen spectrum is shown in figure. There are some transitions A, B, C, D and E. Transition A, B and C respectively represent [CPMT 1986, 88]
A.	First member of Lyman series, third spectral line of Balmer series and the second spectral line of Paschen series
B.	Ionization potential of hydrogen, second spectral line of Balmer series and third spectral line of Paschen series
C.	Series limit of Lyman series, third spectral line of Balmer series and second spectral line of Paschen series
D.	Series limit of Lyman series, second spectral line of Balmer series and third spectral line of Paschen series
Answer» D. Series limit of Lyman series, second spectral line of Balmer series and third spectral line of Paschen series

Discussion

10033.	Two identical charged spherical drops each of capacitance C merge to form a single drop. The resultant capacitance is [AFMC 1993]
A.	Equal to \[2C\]
B.	Greater than \[2C\]
C.	Less than \[2C\] but greater than C
D.	Less than C
Answer» D. Less than C

Discussion

10034.	A liquid of mass m and specific heat c is heated to a temperature 2T. Another liquid of mass m/2 and specific heat 2c is heated to a temperature T. If these two liquids are mixed, the resulting temperature of the mixture is [EAMCET 1992]
A.	(2/3)T
B.	(8/5)T
C.	(3/5)T
D.	(3/2)T
Answer» E.

Discussion

10035.	Assertion : We can measure the potential barrier of a PN junction by putting a sensitive voltmeter across its terminals. Reason : The current through the PN junction is not same in forward and reversed bias.
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

10036.	The magnetic field B with in the solenoid having n turns per metre length and carrying a current of i ampere is given by [MP PET 1993]
A.	\[\frac{{{\mu }_{0}}ni}{e}\]
B.	\[{{\mu }_{0}}ni\]
C.	\[4\pi {{\mu }_{0}}ni\]
D.	ni
Answer» C. \[4\pi {{\mu }_{0}}ni\]

Discussion

10037.	An electric motor operates on a 50 volt supply and a current of 12A. If the efficiency of the motor is 30%, what is the resistance of the winding of the motor [Kerala PET 2002]
A.	\[6\Omega \]
B.	\[4\Omega \]
C.	\[2.9\,\Omega \]
D.	\[3.1\Omega \]
Answer» D. \[3.1\Omega \]

Discussion

10038.	Assertion : Leclanche cell is used, when constant supply of electric current is not required. Reason : The e.m.f. of a Leclanche cell falls, if it is used continuously.
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

10039.	The motion of a rocket is based on the principle of conservation of [AFMC 2000]
A.	Mass
B.	Kinetic energy
C.	Linear momentum
D.	Angular momentum
Answer» D. Angular momentum

Discussion

10040.	The diagram shows-the energy levels for an electron in a certain atom. Which transition shown represents the emission of a photon with the most energy [AIEEE 2005]
A.	I
B.	II
C.	III
D.	IV
Answer» D. IV

Discussion

10041.	A circular coil ?A? has a radius R and the current flowing through it is I. Another circular coil ?B? has a radius 2R and if 2I is the current flowing through it, then the magnetic fields at the centre of the circular coil are in the ratio of (i.e.\[{{B}_{A}}\] to \[{{B}_{B}}\]) [CBSE PMT1993; AIEEE 2002]
A.	4 : 1
B.	2 : 1
C.	3 : 1
D.	1 : 1
Answer» E.

Discussion

10042.	A body of mass M at rest explodes into three pieces, two of which of mass M/4 each are thrown off in perpendicular directions with velocities of 3 m/s and 4 m/s respectively. The third piece will be thrown off with a velocity of [CPMT 1990]
A.	1.5 m/s
B.	2.0 m/s
C.	2.5 m/s
D.	3.0 m/s
Answer» D. 3.0 m/s

Discussion

10043.	Two spherical conductors each of capacity \[C\] are charged to potentials \[V\] and \[-V\]. These are then connected by means of a fine wire. The loss of energy will be [MP PMT 1997]
A.	Zero
B.	\[\frac{1}{2}C{{V}^{2}}\]
C.	\[C{{V}^{2}}\]
D.	\[2C{{V}^{2}}\]
Answer» D. \[2C{{V}^{2}}\]

Discussion

10044.	If velocity of a body is twice of previous velocity, then kinetic energy will become [AFMC 1996]
A.	2 times
B.	\[\frac{1}{2}\]times
C.	4 times
D.	1 times
Answer» D. 1 times

Discussion

10045.	A long straight wire carries an electric current of 2A. The magnetic induction at a perpendicular distance of 5m from the wire is [EAMCET (Med.) 2000]
A.	\[4\times {{10}^{-8}}T\]
B.	\[8\times {{10}^{-8}}T\]
C.	\[12\times {{10}^{-8}}T\]
D.	\[16\times {{10}^{-8}}T\]
Answer» C. \[12\times {{10}^{-8}}T\]

Discussion

10046.	Beats are produced with the help of two sound waves of amplitudes 3 and 5 units. The ratio of maximum to minimum intensity in the beats is [MP PMT 1999]
A.	2 : 1
B.	5 : 3
C.	4 : 1
D.	16 : 1
Answer» E.

Discussion

10047.	Assertion : A rain drop after falling through some height attains a constant velocity. Reason : At constant velocity, the viscous drag is just equal to its weight.
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

10048.	A person will get more quantity of matter in kg ?wt. at [J & K CET 2004]
A.	Poles
B.	At latitude of 60o
C.	Equator
D.	Satellite
Answer» E.

Discussion

10049.	Assertion : The illumination of earth's surface from sun is more at noon than in the morning. Reason : Luminance of a surface refers to brightness of the 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

10050.	Assertion : The polar caps of earth are cold in comparison to equatorial plane. Reason : The radiation absorbed by polar caps is less than the radiation absorbed by equatorial plane.
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

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

The magnetic field \[d\overrightarrow{B}\] due to a small current element \[d\overrightarrow{l\,}\] at a distance \[\overrightarrow{r\,}\] and element carrying current i is, or Vector form of Biot-savart's law is [CBSE PMT 1996; MP PET 2002; MP PMT 2000]

Assertion : A block of wood is floating in a tank containing water. The apparent weight of the floating block is equal to zero. Reason : Because the entire weight of the block is supported by the buoyant force (the upward thrust) due to water.

An alternating voltage is represented as \[E=20\sin 300t.\] The average value of voltage over one cycle will be [MP PMT 2002]

When the temperature is increased the angle of contact of a liquid [AIIMS 1980]

What is the ratio of wavelength of radiations emitted when an electron in hydrogen atom jump from fourth orbit to second orbit and from third orbit to second orbit [MH CET 2004]

If the momentum of a body increases by 0.01%, its kinetic energy will increase by [MP PET 2001]

Assertion : If the net external force on the body is zero, then its acceleration is zero. Reason : Acceleration does not depend on force.

Assertion : A domestic electrical appliance, working on a three pin will continue working even if the top pin is removed. [AIIMS 1995] Reason : The third pin is used only as a safety device.

At \[{{27}^{o}}C\] a gas is suddenly compressed such that its pressure becomes \[\frac{1}{8}th\] of original pressure. Temperature of the gas will be \[(\gamma =5/3)\] [BHU 2000]

A bullet of mass 0.1 kg is fired with a speed of 100 m/sec, the mass of gun is 50 kg. The velocity of recoil is [AFMC 1995; JIPMER 2000; Pb.PMT 2002]

Assertion : Water can be boiled inside satellite by convection. Reason : Convection is the process in which heat is transmitted from a place of higher temperature to a place of lower temperature by means of particles with their migrations from one place to another.

Cathode rays consist of [DCE 1999]

Two identical square rods of metal are welded end to end as shown in figure (i), 20 calories of heat flows through it in 4 minutes. If the rods are welded as shown in figure (ii), the same amount of heat will flow through the rods in [NCERT 1982]

An ac generator produced an output voltage \[E=170\sin 377\,t\,volts\], where t is in seconds. The frequency of ac voltage is [MP PET 1994]

When work is done on a body by an external force, its

What should be the velocity of earth due to rotation about its own axis so that the weight at equator become 3/5 of initial value. Radius of earth on equator is 6400 km [AMU 1999]

A parallel plate air capacitor is charged to a potential difference of V. After disconnecting the battery, distance between the plates of the capacitor is increased using an insulating handle. As a result, the potential difference between the plates [KCET 1999]

Assertion : The isothermal curves intersect each other at a certain point. Reason : The isothermal change takes place slowly, so the isothermal curves have very little slope. [AIIMS 2001]

If the density of a small planet is the same as that of earth, while the radius of the planet is 0.2 times that of the earth, the gravitational acceleration on the surface of that planet is [UPSEAT 2004; CBSE PMT 2005]

A condenser of capacity \[50\,\mu F\]is charged to \[10\ volts\]. Its energy is equal to [CPMT 1978; MP PET 1994; MP PMT 2000]

When \[{{10}^{14}}\] electrons are removed from a neutral metal sphere, the charge on the sphere becomes [Manipal JEE 1995]

Assertion : The amplitude of an oscillating pendulum decreases gradually with time Reason : The frequency of the pendulum decreases with time [AIIMS 2003]

Assertion : In S.H.M., the motion is ?to and fro? and periodic. Reason : Velocity of the particle \[(v)=\omega \sqrt{{{k}^{2}}-{{x}^{2}}}\] (where x is the displacement and k is amplitude) [AIIMS 2002]

Assertion : The surface wave propagation is used for medium wave band and for television broadcasting. Reason : The surface waves travel directly from transmitting antenna to receiver antenna through atmosphere.

Every series of hydrogen spectrum has an upper and lower limit in wavelength. The spectral series which has an upper limit of wavelength equal to 18752 Å is [MP PMT 1993]

A transformer has turn ratio 100/1. If secondary coil has 4 amp current then current in primary coil is [RPET 2000]

Assertion : A direct current flows through a metallic rod, produced magnetic field only outside the rod. Reason : There is no flow of charge carriers inside the rod.

Assertion : In the phenomenon of mutual induction, self induction of each of the coils persists. Reason : Self induction arises when strength of current in same coil changes. In mutual induction, current is changing in both the individual coils.

A man is standing between two parallel cliffs and fires a gun. If he hears first and second echoes after 1.5 s and 3.5s respectively, the distance between the cliffs is (Velocity of sound in air = 340 ms?1) [EAMCET (Med.) 2000]

Two monoatomic ideal gases 1 and 2 of molecular masses m1 and m2 respectively are enclosed in separate containers kept at the same temperature. The ratio of the speed of sound in gas 1 to that in gas 2 is given by [IIT-JEE Screening 2000]

The energy levels of the hydrogen spectrum is shown in figure. There are some transitions A, B, C, D and E. Transition A, B and C respectively represent [CPMT 1986, 88]

Two identical charged spherical drops each of capacitance C merge to form a single drop. The resultant capacitance is [AFMC 1993]

A liquid of mass m and specific heat c is heated to a temperature 2T. Another liquid of mass m/2 and specific heat 2c is heated to a temperature T. If these two liquids are mixed, the resulting temperature of the mixture is [EAMCET 1992]

Assertion : We can measure the potential barrier of a PN junction by putting a sensitive voltmeter across its terminals. Reason : The current through the PN junction is not same in forward and reversed bias.

The magnetic field B with in the solenoid having n turns per metre length and carrying a current of i ampere is given by [MP PET 1993]

An electric motor operates on a 50 volt supply and a current of 12A. If the efficiency of the motor is 30%, what is the resistance of the winding of the motor [Kerala PET 2002]

Assertion : Leclanche cell is used, when constant supply of electric current is not required. Reason : The e.m.f. of a Leclanche cell falls, if it is used continuously.

The motion of a rocket is based on the principle of conservation of [AFMC 2000]

The diagram shows-the energy levels for an electron in a certain atom. Which transition shown represents the emission of a photon with the most energy [AIEEE 2005]

A body of mass M at rest explodes into three pieces, two of which of mass M/4 each are thrown off in perpendicular directions with velocities of 3 m/s and 4 m/s respectively. The third piece will be thrown off with a velocity of [CPMT 1990]

Two spherical conductors each of capacity \[C\] are charged to potentials \[V\] and \[-V\]. These are then connected by means of a fine wire. The loss of energy will be [MP PMT 1997]

If velocity of a body is twice of previous velocity, then kinetic energy will become [AFMC 1996]

A long straight wire carries an electric current of 2A. The magnetic induction at a perpendicular distance of 5m from the wire is [EAMCET (Med.) 2000]

Beats are produced with the help of two sound waves of amplitudes 3 and 5 units. The ratio of maximum to minimum intensity in the beats is [MP PMT 1999]

Assertion : A rain drop after falling through some height attains a constant velocity. Reason : At constant velocity, the viscous drag is just equal to its weight.

A person will get more quantity of matter in kg ?wt. at [J & K CET 2004]

Assertion : The illumination of earth's surface from sun is more at noon than in the morning. Reason : Luminance of a surface refers to brightness of the surface.

Assertion : The polar caps of earth are cold in comparison to equatorial plane. Reason : The radiation absorbed by polar caps is less than the radiation absorbed by equatorial plane.