Which of the following is not a characteristic of electromagnetic waves?
a. they can travel through a vacuum.
b. they can travel at various speeds through any one material.
c. they can be refracted.
d. they can be reflected.

Answer : The incorrect option is, (b) they can travel at various speeds through any one material.

Explanation :

Electromagnetic waves : It is a type of energy which is produced by the oscillating magnetic and electric filed disturbance. Or we can say that it is produced by the movement of electric charged particles through the vacuum or matter.

It is a wave where the two vectors are vibrating mutually perpendicular to each other and in direction of the wave. The two vectors are electric field and magnetic field.

The gamma-rays, x-rays, ultraviolet-rays, infrared-rays, microwaves and radio-waves are the electromagnetic waves.

The characteristic of electromagnetic waves are :

Hence, the incorrect option is, (b) they can travel at various speeds through any one material.

one negative thing it that it can kill water animals. another negative thing is it can cause the destruction of ecosystem. one way water pollution can be reduced is to conserve energy.