A coil, a capacitor and an AC source of rms voltage 24V are connected in series. By varying the frequency of the source, a maximum rms current of 6A is observed. If coil is connected to a dc battery of emf 12 volt and internal resistance 4Ω, then current through it in steady state is :

1) 2.4A
2) 1.8A
3) 1.5A
4) 1.2A

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

Function of a grid in a triode is :

(1) to increase plate voltage

(2) to decrease plate voltage

(3) to reduce the effect of space charge

(4) None

If the degrees of freedom of a gas are f, the ratio of its two specific heats, C_P/C_V, is given by:

1) 1 - (1/f)
2) 1 – (2/f)
3) 1 + (1/f)
4) 1 + (2/f)

A worker does 500 J of work on a 10 kg box. If the box transfers 375 J of heat to the floor through the friction between the box and the floor, what is the velocity of the box after the work has been done on it?

1) 5 m/s
2) 10 m/s.
3) 12.5 m/s
4) 50 m/s

A bob is suspended from a crane by a cable of length l = 5m. The crane and load are moving at a constant speed v. the crane is stopped by a bumper and the bob on the cable swings out an angle of 60°. The initial speed v is ( g=9.8 m/s²)

1) 10 m/s
2) 7 m/s
3) 4 m/s
4) 2 m/s

A black body at high temp T K, radiates energy E. The temperature now fallen to T/ 2 K,the final radiated energy will be : 

1) $$\dfrac{E}{4}$$
2) $$\dfrac{E}{2}$$
3) $$2E$$
4) $$\dfrac{E}{16}$$

A man of mass 70 kg stands on a weighing scale in a lift. Which is moving upwards with a uniform acceleration of 5 m/s^-2?

The reading on the scale is

1) 35 kg

2) 70 kg

3) 105 kg

4) 120 kg

 A bullet with a mass of 10.0 grams and an initial speed of 800 m/s penetrates a distance 5 cm into a fixed block of wood before stopping. The average magnitude of the force exerted by the block on the bullet was

1) 1.3 x 10⁵ N        

2) 6.4 x 10⁵ N

3) 6.4 x 10⁴ N        

4) 1.3 x10³ N

  A kettle with 2 litre waters at 27ºC is heated by operating coil heater of power 1 kW. The heat is lost to the atmosphere at constant rate 160 J/sec when its lid is open. In how much time will water is heated to 77ºC (Sp heat of H2O = 4.2 kJ.mole )

(1)8 min 20 sec     (2) 6 min 2 sec     (3) 14 min     (4) 7 min