Explanation:
In insulators, the electrons are very tightly bound to the nucleus. At a room temperature, thermal energy is not enough to push electrons into conduction band. The energy band gap is very high. Thus the conduction band is empty and the valence band is filled with electrons.
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A long straight wire carries a current of π amp. The magnetic field due to it will be 5 
at what distance from the wire [
permeability of air]
|
(a) |
(b) |
(c) |
(d) |
A photocell stops emission if it is maintained at 2V negative potential. The energy of most energetic photoelectron is
|
(a) 2eV |
(b) 2J |
(c) 2kJ |
(d) 2keV |
With a change of load resistance of a triode, used as an amplifier, from 50 kilo ohms to 100 kilo ohms, its voltage amplification changes from 25 to 30. Plate resistance of the triode is
|
(a) 25 kW |
(b) 75 kW |
(c) 7.5 kW |
(d) 2.5 kW |
Which of the following statements are true about the magnetic susceptibility 
of paramagnetic substance
|
(a) Value of |
|
(b) |
|
(c) |
|
(d) |
The symbol given in figure represents
|
(a) NPN transistor |
(b) PNP transistor |
|
(c) Forward biased PN junction diode |
(d) Reverse biased NP junction diode |
If in a photoelectric experiment, the wavelength of incident radiation is reduced from 6000 Å to 4000 Å then
|
(a) Stopping potential will decrease |
|
(b) Stopping potential will increase |
|
(c) Kinetic energy of emitted electrons will decrease |
|
(d) The value of work function will decrease |
What is the modulation index of an over modulated wave
|
(a) 1 |
(b) Zero |
(c) < 1 |
(d) > 1 |
