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 . 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
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
B.
8 cm
From displacement method, the length of object is given by
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