Question

what is one thing x - rays are used for?
to look inside of luggage at airport security scanners
to receive tv signals
to cook food

Explanation:

X - rays have high energy and can penetrate through many materials. Airport security scanners use X - rays to see inside luggage as they can pass through the outer layers of the luggage and create an image of the contents. TV signals are received using radio waves (a different part of the electromagnetic spectrum). Cooking food is mainly done using microwaves (which cause water molecules in food to vibrate and generate heat).

Answer:

To look inside of luggage at airport security scanners.