Question

Iron glows in red colour when it is heated to very high temperature. The reason for this is:
A.Heat we consume red colour at high temperature.
B.Mechanical energy is being converted to heat energy.
C.All metals glow in red colour when heated.
D.Heat energy is being converted into light energy.

Answer 1

Hint: When iron is heated to a very high temperature, heat energy is supplied to it. When iron glows in red colour, light energy is being produced.

Complete step by step answer:
1. An object appears to be of a certain color when it reflects light of that colour and absorbs other colours. If the heat we supply consumes (absorbs) red colour at high temperature, then iron will never glow red. It glows red because red is reflected and not absorbed. Hence, option A is incorrect.
2. When iron is heated to a very high temperature, heat energy is supplied to it and not mechanical energy. Mechanical energy is used to rotate or move a body, unlike heat energy, which increases the body’s temperature. Hence, option B is incorrect.
3. All metals do not glow red when heated. Some also glow yellow or white when heated. Hence, option C is incorrect.
4. When iron is heated to a very high temperature, heat energy is supplied to it. On supplying heat energy, iron glows red. This is an indication of the heat energy being converted to light energy. Hence, option A is correct.

So, the correct answer is “Option A”.

Note: A body at a very high temperature emits electromagnetic radiation. This phenomenon is called incandescence.