Wave Optics — Physics STD 12 Science — Question

The Lyman series of hydrogen spectrum lies in the region

(a) Infrared

(b) Visible

(c) Ultraviolet

(d) Of X -  rays

n immersion heater is rated 836 watt. It should heat 1 litre of water from 10℃  to 40℃  in about

(a) 200 sec

(b) 150 sec

(c) 836 sec

(d) 418 sec

In a semiconductor

(a) There are no free electrons at any temperature

(b) The number of free electrons is more than that in a conductor

(c) There are no free electrons at 0 K

(d) None of these

If heat is supplied to an ideal gas in an isothermal process:

1. The internal energy of the gas will increase.
2. The gas will do positive work.
3. The gas will do negative work.
4. The said process is not possible.

The radial magnetic field is used in a suspended coil galvanometer to provide:

Sensitivity of potentiometer can be increased by:

A material is placed in a magnetic field, and it is thrown out of it. Then the material is:

In given figure, the potentiometer wire AB has a resistance of 5 W and length 10 m. The balancing length AM for the emf of 0.4 V is

(a) 0.4 m

(b) 4 m

(c) 0.8 m

(d) 8 m

A bar magnet is oscillating in the Earth’s magnetic field with a period T. What happens to its period and motion if its mass is quadrupled

(a) Motion remains S.H.M. with time period = 2T

(b) Motion remains S.H.M. with time period = 4T

(c) Motion remains S.H.M. and period remains nearly constant

(d) Motion remains S.H.M. with time period =