Ray Optics — JEE physics STD 12 Science — Question

Assertion : Only microwaves are used in radar.
Reason : Because microwaves have very small wavelength.

Assertion : Now a days a standard metre is defined as in terms of the wavelength of light.
Reason : Light has no relation with length.

Assertion : Electric appliances with metallic body; e.g. heaters, presses etc, have three pin connections, whereas an electric bulb has a two pin connection.
Reason : Three pin connections reduce heating of connecting cables.

Assertion : Space rockets are usually launched in the equatorial line from west to east.
Reason : The acceleration due to gravity is minimum at the equator.

Assertion : Density is a derived physical quantity.
Reason : Density cannot be derived from the fundamental physical quantities.

Assertion : When two coils are wound on each other, the mutual induction between the coils is maximum.
Reason : Mutual induction does not depend on the orientation of the coils.

Assertion : The instantaneous power of an agent is measured as the dot product of instantaneous velocity and the force acting on it at that instant.
Reason : The unit of instantaneous power is watt.

Assertion : When a light wave travels from a rarer to a denser medium, it loses speed. The reduction in speed imply a reduction in energy carried by the light wave.
Reason : The energy of a wave is proportional to velocity of wave.

Assertion : Water can be boiled inside satellite by convection.
Reason : Convection is the process in which heat is transmitted from a place of higher temperature to a place of lower temperature by means of particles with their migrations from one place to another.