A copper wire of length ll is bent into a semicircle. It is moved with a velocity vv in a region where magnetic field is uniform and perpendicular to the plane of the wire. If the strength of the field is B then emf induced is

1) Blv
2) $$B\displaystyle \dfrac{l}{\pi}v$$
3) $$B\displaystyle \dfrac{2l}{\pi}v$$
4) none of these

A particle is projected up from a point at an angle θθ with the horizontal direction. At any time t, if P is the linear momentum, y is the vertical displacement, x is horizontal displacement, the graph among the following which does not represent the variation of kinetic energy KE of the particle is

1) graph (A)
2) graph (B)
3) graph (C)
4) graph (D)

The velocity of light in a medium is  2 x 10⁸ m /s. The refractive index of the medium is:

(1) 1.0
(2) 1.5
(3) 1.4
(4) 2.3

 A wire tension 225 N produces 6 beats per second when it tuked with a fork, when the tension changed to 256 N, it again tuned with the same tuning fork to no. of beats remained unchanged, the frequency of tuning fork will be

(1) 186             (2) 280

(3) 225             (4) 256

A metal rod expands by 1.00 mm when it is heated from 20 C to 80 C. Another rod of the same material, twice as long as the first at 20 C is heated from 20C to 50 C. The second rod will expand by
 
 (1) 0.25 mm
 (2) 0.50 mm
 (3) 1.00 mm
 (4) 2.00 mm

When an electron and a position collide:

(1) The mass is not converted into energy
(2) They Repel each other
(3) The total mass is converted into energy
(4) Part of the mass is converted into energy

 Work function for a surface is equal to :

(1) Φ = fermi energy – binding energy

(2) Φ =fremi energy

(3) Φ = binding energy – fermi energy

(4) Φ = binding energy

A 20μF capacitor is charged to potential of 500V and is connected to another 10μF capacitor charged to 200V in parallel. The charging batteries are disconnected. The final potential across the combination is:

1) 233.33V

2) 400V

3) 1200V

4) 600V

A conductor of length 2 m carrying current 2 A is held parallel to an infinitely long conductor carrying current of 12 A at a distance of 100 mm, the force j on a small conductor is:

1) 8.6 x 10⁻⁵N
2) 6.6 x 10⁻⁵N
3) 9.6 x 10⁻⁵N
4) 7.6 x 10⁻⁵N

A ball is dropped from rest. What is its speed after 3 seconds?
 
 (1) 15 m/s
 (2) 25 m/s
 (3) 30 m/s
 (4) 45 m/s