- ACircuit 1 and circuit 2.
- BCircuit 2 and circuit 3.
- CCircuit 3 and circuit 1.
- DCircuit 1 only.


Explanation:
In circuit 1, one diode is forward biassed and the other diode is reverse biassed. The forward-biassed diode offers zero resistance (ideally) to the current flow, so it can be replaced by a short circuit. The voltage drop across the first diode will be zero. The second diode is reverse biassed, so it can be replaced by an open circuit; hence, the voltage drop across this diode will be maximum.
In circuit 2, both the diodes are forward biassed, so they can be replaced by short circuits; hence, the voltage drop across both of them will be minimum and equal.
In circuit 3, both the diodes are reverse biassed, so both can be replaced by open circuits; hence, the voltage drop across both of them will be maximum and equal.
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A transistor is used in common emitter mode as an amplifier. Then
|
(a) The base-emitter junction is forward biased |
|
(b) The base-emitter junction is reverse biased |
|
(c) The input signal is connected in series with the voltage applied to the base-emitter junction |
|
(d) a, c |
The resistance of an incandescent lamp is
|
(a) Greater when switched off |
|
(b) Smaller when switched on |
|
(c) Greater when switched on |
|
(d) The same whether it is switched off or switched on |
A metallic block carrying current I is subjected to a uniform magnetic induction as shown in the figure. The moving charges experience a force
given by ........... which results in the lowering of the potential of the face ........ Assume the speed of the carriers to be v
|
(a) eVB |
(b) eVB |
(c) -eVB |
(d) -eVB |
The phase difference between incident wave and reflected wave is 180° when light ray
|
(a) Enters into glass from air |
(b) Enters into air from glass |
|
(c) Enters into glass from diamond |
(d) Enters into water from glass |
At neutral temperature, the thermoelectric power has the value
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(a) Zero |
(b) Maximum but negative |
|
(c) Maximum but positive |
(d) Minimum but positive |