Electrostatic Potential and Capacitance — Physics STD 12 Science — Question

Assertion  : In high latitude one sees colourful curtains of light hanging down from high altitudes.

Reason      :  The high energy charged particles from the sun are deflected to polar regions by the magnetic field of the earth.

(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.

If three bulbs 60W, 100W and 200W are connected in parallel, then

(a) 200 W bulb will glow more	(b) 60 W bulb will glow more
(c) 100 W bulb will glow more	(d) All the bulbs will glow equally

On applying an external magnetic field, to a ferromagnetic substance domains.

The unit of dipole moment is:

The fringe width in interference of light due to two coherent sources is :

In P-N junction, avalanche current flows in circuit when biasing is

(a) Forward

(b) Reverse

(c) Zero

(d) Excess

The wavelength of a monochromatic light is 6000 Å in vacuum. When it enters in the glass slab of refractive index 2 its wavelength will be :

In the uranium radioactive series, the initial nucleus is  and the final nucleus is  . When the uranium nucleus decays to lead, the number of α - particles emitted will be

(a) 1

(b) 2

(c) 4

(d) 8

A silver ball of radius 4.8 cm is suspended by a thread in the vacuum chamber. UV light of wavelength 200 nm is incident on the ball for some times during which a total energy of 1 × 10^–7 J falls on the surface. Assuming on an average one out of 10³ photons incident is able to eject electron. The potential on sphere will be

(a) 1 V

(b) 2 V

(c) 3 V

(d) Zero

A coil of insulating wire is connected to battery. If it is moved towards a galvanometer then its point gets deflected because.