41.

Two bulbs rated 200 W, 220V and 100 W, 220V, are connected in series, combination is connected to 220 V supply. Power consumed by the circuit is

• 8O W

• 67 W

• 76 W

• 65 W

Magnetic field intensify at the centre of coil of 50 turns, 0.5 m radius and carrying a current of 2A, is

• 5x 10^-5 T

• 3 x 10^-5 T

• 1.25 × 10^-4 T

• 0.5 x 10^-5 T

The minimum wavelength of X-ray emitted by X-ray tube is 0.4125 $\stackrel{\circ }{\mathrm{A}}$. The accelerating voltage is

• 30 kV

• 50 kV

• 80 kV

• 60 kV

A straight conductor of length 0.4 m is moved with a speed of 7 m/s perpendicular to the magnetic field of intensity of 0.9 Wb/m². The induced emf across the conductor will be

• 7.25 V

• 5.54 V

• 1.25 V

• 2.52 V

The nature of light waves is similar to

• cosmic rays

• cathode rays

• gamma rays

• alpha rays

A conducting sphere ofradius 30 cm is given a charge of 1.2 x 10^-8 C. What will be its potential ?

• 0.03 kV

• 0.9 kV

• 1.8 kV

• 3.6 kV

The energy of an X-ray photon is 2 keV, then its frequency will be

• 3.2 x 10^-6 per second

• 5 x 10¹⁷ per second

• 2 x 10¹⁷ per second

• 2 × 10¹⁸ per second

A convex lens makes a real image of 4 cm long on a screen when the lens is shifted to a new position without disturbing the object or the screen, we get a real image on the screen, which is 16 cm long, then the length of the object is

• 3/4 cm

• 8 cm

• 20 cm

• 2 cm

An astronomical telescope has an objective of focal length 100 cm and magnifying power of the distance between the two lenses in normal adjustment will be

• 106 cm

• 102 cm

• 92 cm

• 78 cm

Which of the following is not correct regarding the radio telescope?

• It cannot work at night

• It can detect a very faint radio signal

• It can be operated even in cloudly weather

• It is much cheaper than optical telescope