A 5℃ rise in temperature is observed in a conductor by passing a current. When the current is doubled the rise in temperature will be approximately
|
(a) 16 ℃ |
(b) 10 ℃
|
(c) 20 ℃ |
(d) 12 ℃ |
(c) 20 ℃
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The north and south poles of two identical magnets approach a coil, containing a condenser, with equal speeds from opposite sides. Then
|
(a) Plate 1 will be negative and plate 2 positive |
|
(b) Plate 1 will be positive and plate 2 negative |
|
(c) Both the plates will be positive |
|
(d) Both the plates will be negative |
A plane mirror is approaching you at a speed of 10 cm/sec You can see your image in it. At what speed will your image approach you
| (a) 10 cm/sec | (b) 5 cm/sec | (c) 20 cm/sec | (d) 15 cm/sec |
The ratio of secondary to the primary turns in a transformer is 3 : 2. If the power output be P, then the input power neglecting all loses must be equal to
|
(a) 5 P |
(b) 1.5 P |
(c) P |
(d) |
There is no couple acting when two bar magnets are placed coaxially separated by a distance because
|
(a) There are no forces on the poles |
|
(b) The forces are parallel and their lines of action do not coincide |
|
(c) The forces are perpendicular to each other |
|
(d) The forces act along the same line |
A condenser of capacity 
is charged to a potential 
. The electrostatic energy stored in it is 
. It is connected to another uncharged condenser of capacity 
in parallel. The energy dissipated in the process is
|
(a) |
(b) |
(c) |
(d) |
A radio transmitter operates at a frequency of 880 kHz and a power of 10 kW. The number of photons emitted per second are
|
(a) 1.72 |
(b) 1327 |
(c) 13.27 |
(d) 0.075 |
In extrinsic P and N-type, semiconductor materials, the ratio of the impurity atoms to the pure semiconductor atoms is about
|
(a) 1 |
(b) |
(c) |
(d) |
