Question

will electric & magnetic fields affect electromagnetic waves

Answer 1

em waves are oscillating magnetic and electric waves so will they get affected by electric and magnetic fields yes since they are the waves which correspond to thse

Answer 2

em waves are oscillating magnetic and electric fields rather than waves themselves..rest idea remains same..

Answer 3

If what you mean to ask is whether EM waves change because of nearby electric and magnetic fields, or vice versa, then the answer is technically yes, but this is a higher-order effect, meaning it is very very small under ordinary conditions, and you need truly massive fields (e.g. those at the surface of a neutron star) to notice anything.

To a first approximation, and in all ordinary situations, you can assume the fields caused by EM waves and any fields due to sources (like charges or currents) simply add together. Hence, EM waves will not be changed by contact with fields due to sources, and vice versa. Keep in mind, however, that anything that can respond to electric and magnetic fields (like moveable charges) will be affected by the sum of the fields produced by EM waves and any static fields.