When e.m. waves strike a surface, they exert..........on it.

What are e.m. waves?How are they produced?

When a.c. flows through a resistor, the e.m.f. is in ........with the current.

What does an e.m. wave consist of?

State whether the following statement is true or false-"When a person walks on a rough surface,the frictional force exerted by the surface on the person is opposite to the direction of his motion".

Name the e.m. waves which are used for the treatment of certain forms of cancer. Write their frequency range.

An object weighs 10 N when measured on the surface of the earth. What would be its weight when measured on the surface of the moon?

The e.m. waves of radio frequency cannot be reflected by ionosphere. (True/False)

The e.m. waves of radio frequency cannot be reflected by ionosphere. (True/False)