Alternating Current — JEE physics STD 12 Science — Question

Assertion : Machine parts are jammed in winter.
Reason : The viscosity of lubricant used in machine parts increase at low temperature.

Assertion : The illumination of earth's surface from sun is more at noon than in the morning.
Reason : Luminance of a surface refers to brightness of the surface.

Assertion : The properties of paramagnetic and ferromagnetic substance are not effected by heating.
Reason : As temperature rises, the alignment of molecular magnets gradually decreases.

Assertion : If an electric fan be switched on in a closed room, the air of the room will be cooled.
Reason : Fan air decrease the temperature of the room.

Assertion : Sine and cosine functions are periodic functions.
Reason : Sinusoidal functions repeats it values after a definite interval of time.

Assertion : Steel is more elastic than rubber.
Reason : Under given deforming force, steel is deformed less than rubber.

Assertion : When a solid iron ball is heated, percentage increase is its volume is largest.
Reason : Coefficient of superficial expansion is twice that of linear expansion where as coefficient of volume expansion is three time of linear expansion.

Assertion : A large soap bubble expands while a small bubble shrinks, when they are connected to each other by a capillary tube.
Reason : The excess pressure inside bubble (or drop) is inversely proportional to the radius.

Assertion : For the sensitivity of a camera, its aperture should be reduced.
Reason : Smaller the aperture, image focussing is also sharp.

Assertion : Zener diode works on a principle of breakdown voltage.
Reason : Current increases suddenly after breakdown voltage.