A step-up transformer is used on a 120V line to provide a potential difference of 2400 V. If the primary coil has 75 turns, the number of turns in the secondary coil is
The more readily fissionable isotope of uranium has an atomic mass of
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A bomb of mass 9Kg explodes into two pieces of masses 3Kg and 6Kg. The velocity of the 3Kg mass is 16 ms-1. Then kinetic energy of 6Kg mass is
Two inclined plane have same height but different lengths (and therefore different angles). If a solid sphere is allowed to roll down from the top of these inclined planes
Cathode rays are produced when the pressure is of the order of
To convert a galvanometer into a voltmeter one should connect a
A two meter wire is moving with a velocity of 1 m/s perpendicular to a magnetic field of 0.5 Wb/m2. The emf induced in it will be
A transistor is operated in CB mode. If the collector base voltage is reduced to zero keeping the input current undisturbed, the output current will be:
Two bodies having the same mass 2 kg each have different surface areas 50 m2 and 100 m2 in contact with a horizontal plane. If the coefficient of friction is 0.2, the forces of friction that come into play when they are in motion will be in the ratio
Figure shows two large cylindrical shells having uniform linear charge densities + λ and - λ . Radius of inner aylinder is 'a' and that of outer cylinder is 'b'. A charged particle of mass m , charge q revolves in a circle of radius r. Then its speed 'V' is:
[Neglect gravity and assume the radii of both cylinders to be very small in comparison to their length]
A slab consists of two parallel layers of two different materials of same thickness having thermal conductivities k₁ and k₂. The equivalent conductivity of the combination is
The eccentricity of earth's orbit is 0.0167. The ratio of its maximum speed in its orbit to its minimum speed is
When volume of system is increased two times and temperature is decreased half of its initial temperture, then pressure becomes
A spring balance is attached to the ceiling of a lift. A man hangs his bag on the spring and the balance reads 49 N when the lift is stationary. If the lift moves downwards with an acceleration of 5 m/s2, the reading of the spring balance would be
A conductor of length l carrying current i is placed perpendicular to magnetic field of induction B. The force experienced by it is
In a deflection magnetometer experiment the deflections produced separately by two short bar magnets kept at the same distance are 45o and 30o . Then the ratio of the magnetic moments of the two magnets is
If ball A is dropped from the top of a building and another ball B is thrown horizontally from the same height at the same moment with the same velocity, then ball
A boat crosses a river from port A to port B, which are just on the opposite side. The speed of the water is Vw and that of boat is VB relative to water. Assume VB = 2 VW. What is the time taken by the boat, if it has to cross the river directly on the AB line?
A gun fires a bullet of mass 50gm with a velocity of 30m/s. Because of this gun is pushed back with a velocity of 1m/s. Mass of the gun is
A particle of mass 10 grams is executing simple harmonic motion with an amplitude of 0.5 m and angular frequency 10 radians/sec. The maximum value of the force acting on the particle during the course of the oscillation is
A particle reaches its highest point when it has covered exactly one half of its horizontal range. The corresponding point on the displacement time graph is characterised by
At what temperature is the r.m.s velocity of a hydrogen molecule equal to that of an oxygen molecule at 47oC?
The maximum energy received by the earth from the sun is in the form of
The moment of Inertia of a solid cylinder of mass M and radius R about a line parallel to the axis of the cylinder but lying on the surface of the cylinder is
Which of the following is example of a scalar quaintly?
Two pieces of glass plate one upon the other with a little water in between them cannot be separated easily because of
Electric room radiator which operates at 225 volts has resistance of 50 ohms. Power of the radiator is approximately
Two marks on a glass rod 10cm apart are found to increase their distance by 0.08mm when the rod is heated from 0 oC to 100 oC. A flask made of the same glass as that of rod measures a volume 1000c.c at 0 oC. The volume it measures at 100 oC in c.c is