An ac source is rated at 220V, 50Hz. The time taken for voltage to change from its peak value to zero is
X - rays which can penetrate through longer distances in substances are called
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An air capacitor of capacity C = 10μ F is connected to a constant voltage battery of 12 volt. Now the space between the plates is filled with a liquid of dielectric constant 5. The charge that flows now from battery to the capacitor is
An oxide coated filament is useful in vacuum tubes because essentially
A bomb of 12 kg explodes into two pieces of masses 4 kg and 8 kg. The velocity of 8 kg mass is 6 m/sec. The kinetic energy of the other mass is
An electrical cable having a resistance of 0.2 Ω delivers 10 kW at 200 V.D.C. to a factory. What is the efficiency of transmission?
Which of the following law is used in the Millikan's method for the determination of charge?
A generator at a utility company produces 100 A of current at 4000 V. The voltage is stepped up to 240000 V by a transformer before it is sent on a high voltage transmission line. The current in transmission line is
Which quantity is increased in step-down transformer ?
A rectangular, a square, a circular and an elliptical loop, all in the (x - y) plane, are moving out of a uniform magnetic field with a constant velocity, The magnetic field is directed along the negative z axis direction. The induced emf, during the passage of these loops, out of the field region, will not remain constant for:
The pressure exerted by an electromegnetic wave of intensity I on a non-reflecting surface is (where c = Velocity of light)
What is the value of inductance L for which the current is a maximum in series LCR circuit with C = 10 μF and ω = 1000s−1 ?
An electric dipole is kept in a uniform electric field. It experiences
Two capacitors of capacity 4μF and 6μF are connected in series and a battery is connected to the combination the energy stored is E1. If they are connected in parallel and if the same battery is connected to this combination the energy stored is E2. The ratio of E1 and E2 is
The same retarding force is applied to stop a train. The train stops after 80 m. If the speed is doubled, then the distance will be
A light and a heavy body have equal kinetic energy. Which one has a greater momentum ?
The energy emitted per second by a black body at 27ºC is 10 J. If the temperature of the black body is increased to 327ºC, the energy emitted per second will be
A 4μ F conductor is charged to 400 volts and then its plates are joined through a resistance of 1 k Ω. The heat produced in the resistance is
A certain amount of current when flowing in a properly set tangent galvanometer, produces a deflection of 45º. If the current be reduced by a factor of √3, the deflection would
A steel wire of length 'L' has a magnetic moment 'M'. The wire is bent into a semi circular arc its magnetic moment will be
If rope of lift breaks suddenly, the tension exerted by the surface of lift (a=acceleration of lift)
The work done in stretching a wire by 1 mm is 4 J. The work done in stretching another wire of the same material, but with double the radius and half the length by 2 mm is
The P.E. of a simple harmonic oscillator, when the particle is half way to its end point is
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): A parallel plate capacitor is connected across battery through a key. A dielectric slab of constant K is introduced between the plates. The energy stored becomes K times.
Reason(R): The surface density of charge on the plates remains constant or unchanged.
In the following question, a Statement-1 is given followed by a corresponding Statement-2 just below it. Read the statements carefully and mark the correct answer-
Statement-1:
Two cylinders, one hollow (metal) and the other solid (wood) with the same mass and identical dimensions are simultaneously allowed to roll without slipping down an inclined plane from the same height. The hollow cylinder will reach the bottom of the inclined plane first.
Statement-2:
By the principle of conservation of energy, the total kinetic energies of both the cylinders are identical when they reach the bottom of the incline.
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): Infrared radiations are used to preserve food stuffs.
Reason(R): Infrared radiations are produced by ionised gases.
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A):Nuclei having number about 60 are most stable.
Reason(R):When two or more light nuclei are combined into a heavier nucleus, then the binding energy per nucleon will increase.
3 videos|44 docs|66 tests
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3 videos|44 docs|66 tests
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