- A
- B
- C
- D
Explanation:
In the uniform Electric field the net electric force on the dipole is alwas zero.

In uniform Electric field the torque on the dipole due to field may be zero.

T = 0
Here t Þ Torque
$\text{T}=2\text{qEl}\sin\text{q }\otimes\neq0$
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
A short bar magnet with its north pole facing north forms a neutral point at P in the horizontal plane. If the magnet is rotated by 90o in the horizontal plane, the net magnetic induction at P is (Horizontal component of earth’s magnetic field =
)
|
(a) 0 |
(b) 2 |
(c) |
(d) |
In a transistor, a change of 8.0 mA in the emitter current produces a change of 7.8 mA in the collector current. What change in the base current is necessary to produce the same change in the collector current
| (a) 50 mA | (b) 100 mA | (c) 150 mA | (d) 200 mA |
An electric fan and a heater are marked as 100 watt, 220 volt and 1000 watt, 220 volt respectively. The resistance of the heater is
|
(a) Zero |
(b) Greater than that of the fan |
|
(c) Less than that of the fan |
(d) Equal to that of the fan |
In Bohr model of hydrogen atom, the ratio of periods of revolution of an electron in n = 2 and n = 1 orbits is
|
(a) 2 : 1 |
(b) 4 : 1 |
(c) 8 : 1 |
(d) 16 : 1 |
Assertion : To protect any instrument from external magnetic field, it is put inside an iron body.
Reason : Iron is a magnetic substance.
|
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. |
|
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion. |
|
(c) If assertion is true but reason is false. |
|
(d) If the assertion and reason both are false. |
Consider an optical communication system operating at l~ 800 nm. Suppose, only 1% of the optical source frequency is the available channel bandwidth for optical communication. How many channels can be accommodated for transmitting audio signals requiring a bandwidth of 8 kHz
|
(a) 4.8 × 108 |
(b) 48 |
(c) 6.2 × 108 |
(d) 4.8 × 105 |