In Bainbridge mass spectrograph a potential difference of 1000 V is applied between two plates distant 1 cm apart and magnetic field in B = 1T. The velocity of undeflected positive ions in m/s from the velocity selector is
|
(a) |
(b) |
(c) |
(d) |
(c) 
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The number of turns in the primary coil of a transformer is 200 and the number of turns in the secondary coil is 10. If 240 volt AC is applied to the primary, the output from the secondary will be
|
(a) 48 V |
(b) 24 V |
(c) 12 V |
(d) 6 V |
The dual nature of light is exhibited by
|
(a) Photoelectric effect |
(b) Refraction and interference |
|
(c) Diffraction and reflection |
(d) Diffraction and photoelectric effect |
Gases begin to conduct electricity at low pressure because
|
(a) At low pressure, gases turn to plasma |
|
(b) Colliding electrons can acquire higher kinetic energy due to increased mean free path leading to ionisation of atoms |
|
(c) Atoms break up into electrons and protons |
|
(d) The electrons in atoms can move freely at low pressure |
The idea of secondary wavelets for the propagation of a wave was first given by
|
(a) Newton |
(b) Huygen |
(c) Maxwell |
(d) Fresnel |
For a triode m = 64 and gm =1600 m mho. It is used as an amplifier and an input signal of 1V (rms) is applied. The signal power in the load of 40 kW will be
|
(a) 23.5 mW |
(b) 48.7 mW |
(c) 25.6 mW |
(d) None of these |
If a convex lens of focal length 80 cm and a concave lens of focal length 50 cm are combined together, what will be their resulting power
|
(a) + 6.5D |
(b) – 6.5 D |
(c) + 7.5 D |
(d) – 0.75 D |
Zener breakdown in a semi-conductor diode occurs when
|
(a) Forward current exceeds certain value |
(b) Reverse bias exceeds certain value |
|
(c) Forward bias exceeds certain value |
(d) Potential barrier is reduced to zero |
