a type of radiation (= energy from heat or light that you cannot see) in the form of electromagnetic waves (= waves in which both magnetic and electric fields may change at the same time), including X-rays, radio waves, visible light, and gamma rays

Mobile devices such as phones can emit powerful electromagnetic radiation. 手机等移动设备会发出强大的电磁辐射。

We are facing a significant increase in electromagnetic radiation from power lines.