Intrinsic semiconductor is electrically neutral. Extrinsic semiconductor having large number of current carriers would be
|
(a) Positively charged |
|
(b) Negatively charged |
|
(c) Positively charged or negatively charged depending upon the type of impurity that has been added |
|
(d) Electrically neutral |
(d) Electrically neutral
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A battery is charged at a potential of 15 V for 8 hours when the current flowing is 10 A. The battery on discharge supplies a current of 5 A for 15 hours. The mean terminal voltage during discharge is 14 V. The "Watt-hour" efficiency of the battery is
|
(a) 82.5% |
(b) 80 % |
(c) 90% |
(d) 87.5% |
A moving coil galvanometer has 150 equal divisions. Its current sensitivity is 10 divisions per milliampere and voltage sensitivity is 2 divisions per millivolt. In order that each division reads 1 volt, the resistance in ohms needed to be connected in series with the coil will be
|
(a) 99995 |
(b) 9995 |
(c) |
(d) |
A rocket is going towards moon with a speed v. The astronaut in the rocket sends signals of frequency v towards the moon and receives them back on reflection from the moon. What will be the frequency of the signal received by the astronaut (Take v << c)
|
(a) |
(b) |
(c) |
(d) |
A parallel plate capacitor with air as medium between the plates has a capacitance of 10 μF. The area of capacitor is divided into two equal halves and filled with two media as shown in the figure having dielectric constant 
and 
. The capacitance of the system will now be
|
(a) 10 μF |
(b) 20 μF |
(c) 30 μF |
(d) 40 μF |
The time period of rotation of the sun is 25 days and its radius is 7
. The Doppler shift for the light of wavelength 6000 Å emitted from the surface of the sun will be
|
(a) 0.04 Å |
(b) 0.40 Å |
(c) 4.00 Å |
(d) 40.0 Å |
When the current i is flowing through a conductor, the drift velocity is v. If 2i current is flowed through the same metal but having double the area of cross-section, then the drift velocity will be
|
(a) v/4 |
(b) v/2 |
(c) v |
(d) 4v |
20 μA current flows for 30 seconds in a wire, transfer of charge will be
|
(a) 2 |
(b) 4 |
(c) 6 |
(d) 8 |
