Donor type impurity is found in
|
(a) Trivalent elements |
(b) Pentavalent elements |
|
(c) In both the above |
(d) None of these |
Donor type impurity is found in
|
(a) Trivalent elements |
(b) Pentavalent elements |
|
(c) In both the above |
(d) None of these |
(b) Pentavalent elements
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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 |
If a coil made of conducting wires is rotated between poles pieces of the permanent magnet. The motion will generate a current and this device is called
|
(a) An electric motor |
(b) An electric generator |
|
(c) An electromagnet |
(d) All of above |
Under which of the following conditions will a convex mirror of focal length f produce an image that is erect, diminished and virtual
|
(a) Only when 2f > u > f |
(b) Only when u = f |
|
(c) Only when u < f |
(d) Always |
The magnetic field due to the earth is closely equivalent to that due to
|
(a) A large magnet of length equal to the diameter of the earth |
| (b) A magnetic dipole placed at the centre of the earth |
| (c) A large coil carrying current |
| (d) Neither of the above |
Resistance as shown in figure is negative at
|
(a) A |
(b) B |
(c) C |
(d) None of these |