Alternating Current — Physics STD 12 Science — Question

Assertion :   The properties of paramagnetic and ferromagnetic substance are not effected by heating.
Reason     : As temperature rises, the alignment of molecular magnets gradually decreases.(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 assertion is false but reason is true.

In summer, a mild wind is often found on the shore of a calm river. This is caused due to,

1. Difference in thermal conductivity of water and soil.
2. Convection currents.
3. Conduction between air and the soil.
4. Radiation from the soil.

Photons of energy 6 eV are incident on a metal surface whose work function is 4 eV. The minimum kinetic energy of the emitted photo-electrons will be(a) 0 eV(b) 1 eV(c) 2 eV(d) 10 eV

An α -particle is accelerated through a potential difference of 200V. The increase in its kinetic energy is (a) 100 eV(b) 200 eV(c) 400 eV(d) 800 eV

An electric dipole is placed at the centre of a sphere.
Mark the correct options:

Assertion  : Radio waves can be polarised.
Reason     : Sound waves in air are longitudinal in nature. (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.