- AThe number of turns in the coil
- BThe resistance of the coil
- CThe speed of approach of the magnet
- DAll the above
Explanation:
The induced emf produced when a magnet is inserted into a coil does not depend upon the resistance of the coil.
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An electron moving towards the east enters a magnetic field directed towards the north. The force on the electron will be directed
|
(a) Vertically upward |
(b) Vertically downward |
|
(c) Towards the west |
(d) Towards the south |
The magnetic induction at the centre O in the figure shown is
|
(a) |
(b) |
(c) |
(d) |
Unit of radioactivity is Rutherford. Its value is
|
(a) 3.7 |
(b) 3.7 |
|
(c) 1.0 |
(d) 1.0 |
For a cell of e.m.f. 2V, a balance is obtained for 50 cm of the potentiometer wire. If the cell is shunted by a 2Ω resistor and the balance is obtained across 40 cm of the wire, then the internal resistance of the cell is
|
(a) 0.25 Ω |
(b) 0.50 Ω |
(c) 0.80 Ω |
(d) 1.00 Ω |
In Bohr’s model, if the atomic radius of the first orbit is
, then the radius of the fourth orbit is
|
(a) |
(b) 4 |
(c) |
(d) 16 |
When a bar magnet falls through a long hollow metal cylinder fixed with its axis vertical, the final acceleration of the magnet is
|
(a) Equal to zero |
|
(b) Less than g |
|
(c) Equal to g |
|
(d) Equal to g in to beginning and then more than g |
The binding energy of the innermost electron in tungsten is 40 keV. To produce characteristic X-rays using a tungsten target in an X-rays tube the potential difference V between the cathode and the anti-cathode should be
|
(a) V< 40 kV |
(b) V ≤ 40 kV |
(c) V > 40 kV |
(d) V >/< 40 kV |
A ray of light is incident at 50° on the middle of one of the two mirrors arranged at an angle of 60° between them. The ray then touches the second mirror, get reflected back to the first mirror, making an angle of incidence of
|
(a) 50° |
(b) 60° |
(c) 70° |
(d) 80° |