Wave Optics — 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.

An ideal coil of 10 henry is joined in series with a resistance of 5 ohm and a battery of 5 volt.  2 second after joining, the current flowing in ampere in the circuit will be

(a)

(b)

(c) (1 – e)

(d) e

A railway compartment is lit up by thirteen lamps each taking 2.1 amp at 15 volts. The heat generated per second in each lamp will be

(a) 4.35 cal

(b) 5.73 cal

(c) 7.5 cal

(d) 2.5 cal

Two lithium nuclei in a lithium vapour at room temperature do not combine to form a carbon nucleus because:

1. A lithium nucleus is more tightly bound than a carbon nucleus.
2. Carbon nucleus is an unstable particle.
3. It is not energetically favourable.
4. Coulomb repulsion does not allow the nuclei to come very close.

Voltage in the secondary coil of a transformer does not depend upon.

(a) Voltage in the primary coil

(b) Ratio of number of turns in the two coils

(c) Frequency of the source

(d) Both (a) and (b)

The energy required to knock out the electron in the third orbit of a hydrogen atom is equal to

(a) 13.6 eV

(b) +

(c) -

(d) -

The speed of light depends:

The maximum power drawn out of the cell from a source is given by (where r is internal resistance)

(a)

(b)

(c)

(d)

When the number of turns in a coil is doubled without any change in the length of the coil, its self inductance becomes

(a) Four times

(b) Doubled

(c) Halved

(d) Unchanged