Moving Charges and Magnetism — Physics STD 12 Science — Question

Identify the correct statement about the charges q_1​ and q_2​:

At a point 20 cm from the centre of a uniformly charged dielectric sphere of radius 10 cm, the electric field is 100 V/m. The electric field at 3 cm from the centre of the sphere will be

(a) 150 V/m

(b) 125 V/m

(c) 120 V/m

(d) Zero

In a Bainbridge mass spectrometer positive rays of the same element produce different traces. The traces correspond to:

The charge on proton is:

At the surface of a charged conductor electrostatic field must be _____ to the surface at every point.

The potential at a point, due to a positive charge of 100μC  at a distance of 9m, is

(a)  V

(b)  V

(c)  V

(d)  V

Assertion  :   X-rays can penetrate through the flesh but not through the bones.

Reason      : The penetrating power of X-rays depends on voltage.

(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.

The separation between the plates of a charged parallel-plate capacitor is increased. Which of the following quantities will change?

1. Charge on the capacitor.
2. Potential difference across the capacitor.
3. Energy of the capacitor.
4. Energy density between the plates.

S.I. unit of decay constant is :

The wavelength of Lyman series is

(a)

(b)

(c)

(d)