Practice MCQ Questions and answers on Physics-GK

Radiation is the transfer of heat energy through space by electromagnetic radiation. Most of the electromagnetic radiation that comes to the earth from the sun is invisible.

Conduction is the transfer of heat between substances that are in direct contact with each other. Conduction occurs when a substance is heated, particles will gain more energy, and vibrate more. These molecules then bump into nearby particles and transfer some of their energy to them.

A body absorbs heat most if it is black and rough.

A black body can absorb radiations of all wavelengths.

Cover of the solar cooker is made of glass because glass allows the sunlight to pass through it and concentrate at one focal point, it also prevents heat to escape out of the cooker.

Polished surfaces are poor radiators of heat. So loss of heat on that account is reduced and the electric iron remains hotter than otherwise.

Both the floor and the carpet have the same temperature as both are exposed to the same atmosphere. So the feet losing more heat, the floor appears cooler to the feet.

Global warming is expected to result in increase in level of sea, change in crop pattern and change in coast line.

Two thin shirts can keep us warmer than a single thick shirt in winter because of the air that is trapped between the two thin shirts. This air acts as an insulator and ensures that heat does not escape.

Sun's heat reaches us by radiation.