Electric Charges and Fields — Physics STD 12 Science — Question

In case of Coulomb’s law, the value of k is given by:

A free electron is placed in the path of a plane electromagnetic wave. The electron will start moving:

1. Along the electric field.
2. Along the magnetic field.
3. Along the direction of propagation of the wave.
4. In a plane containing the magnetic field and the direction of propagation.

The electron cannot exist inside the nucleus because:

In a negative logic the following wave form corresponds to the

(a) 0000000000

(b) 0101101000

(c) 1111111111

(d) 1010010111

Demagnetisation of magnets can be done by

(a) Rough handling	(b) Heating
(c) Magnetising in the opposite direction	(d) All the above

16 gm sample of a radioactive element is taken from Bombay to Delhi in 2 hour and it was found that 1 gm of the element remained (undisintegrated). Half life of the element is

(a) 2 hour

(b) 1 hour

(c)

(d)

Which of the following statement is incorrect

(a) Both ac and dc dynamo have a field magnet

(b) Both ac and dc dynamo have an armature

(c) Both ac and dc dynamo convert mechanical energy into electrical energy

(d) Both ac and dc dynamo have slip rings

The amount of work done by the cell on a unit positive charge carrier to force it to go to the point of higher potential is called:

The electrons of Rutherford’s model would be expected to lose energy because, they: