The alternating voltage induced in the secondary coil of a transformer is mainly due to
Photons of energy 1eV and 2.5 eV successively illuminate a metal whose work function is 0.5 eV. The ratio of the maximum speeds of the electrons emitted will be
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What is the de Broglie wavelength (in Å) of the alpha- particle accelerated through a potential difference V ?
A stationary nucleus of mass M emits an electron of mass 'm' with a velocity 'v'. If the recoil velocity of the nucleus is V, the ratio of the de Broglie wave lengths of the nucleus and the electron is
A body of mass m is moving in a circle of radius r with a constant speed υ. The force on the body is mυ2/r and is directed towards the centre. What is the work done by this force in moving the body over half the circumference of the circle
An electron beam is subjected to perpendicular magnetic and electric fields of 5 x 10 − 4 w b m − 2 and 3 x 10 3 V m − 1 resectively. If there is no deflection, the velocity of electrons is
In a Wheatstone's bridge, all the four arms have equal resistance R. If resistance of the galvanometer arm is also R, then equivalent resistance of the combination is
A photoelectric cell is illuminated by a point source of light 1 m away. When the source is shifted to 2 m, then
When yellow light is incident on a surface, no electrons are emitted while green light can emit. If red light is incident on the surface, then
For a given kinetic energy which of the following has the smallest de-Broglie wave-length ?
The effective value of a.c. in a circuit is 10 A. The peak value of current is
When light travels from air to water, which parameter does not change?
In an electromagnetic wave, the electric and magnetising fields are 100 Vm-1 and 0.265 Am-1. The maximum energy flow is
Three point charges -q, Q and -q are placed at equal distances on a straight line. If total potential energy of the system is zero, then the ratio of Q/q is
Figure shows a solid hemisphere with a charge of 5nC distributed uniformly through its volume. The hemisphere lies on a plane and point P is located on the plane, along a radial line from the centre of curvature at distance 15cm. The electric potential at point P due to the hemisphere is:
Two sphere of mass m and M are situated in air and the gravitational force between them is F. The space around the masses is now filled with a liquid of specific gravity 3. The gravitational force will now be
The specific heats at constant pressure is greater than that of the same gas at constant volume because
A body is imparted motion from rest to move in a straight line. If it is then obstructed by an opposing force, then
Two parallel wires of length 9m each are separated by a distance of 0.15m. If they carry equal currents in the same direction and exert a total force of 30 x 10 − 7 N on each other, the value of current must be
A body takes T minutes to cool from 62°C to 61°C when the surrounding temperature is 30°C. The time taken by the body to cool from 46°C to 45.5°C is
A vibration magnetometer is placed at South pole, then the time period will be
Which of the following materials is repelled by an external magnetic field?
If the radius of a soap bubble is four times that of another, then the ratio of their pressures will be
The extension in a string, obeying the Hooke's law, is x. The speed of sound in the stretched string is v. If the string is extended to 1.5 x, then speed of sound will be
If 200 Mev energy is released in the fission of a single nucleus of 92U235 , how many fissions must occur per second to produce a power of 1 kW?
A simple pendulum of length 'l' has a maximum angular displacement (θ). The energy of a bob of mass m at the end of the displacement is
In a Huygen's eye piece with an eyepiece of focal length F, the distance between the eye-piece and field lens should be
26 videos|287 docs|64 tests
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26 videos|287 docs|64 tests
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