Electromagnetic Radiation
Electromagnetic radiation is energy that travels in waves through space, like the signals your cell phone sends and receives.
A microwave oven sends invisible waves of energy into your food. The waves travel through the air inside the oven. They hit the food and make it warm. Electromagnetic radiation works the same way — energy moves through space in waves until it hits something.
Explaining electromagnetic radiation by grade level
Your cell phone sends out waves you cannot see or feel. These waves carry your voice to other phones far away. They move through the air at very high speed. Light from the sun travels the same way.
Projects that explore electromagnetic radiation
Electromagnetic radiation travels in waves through space, and different sources release different amounts of wave energy. You can measure this by filling three test tubes with 10 ml of water and recording the starting temperature before and after a phone rings nearby. None of the three phones raise the temperature at all over two minutes, confirming that this radiation carries too little energy to warm water.
Cell phone signals are a form of electromagnetic radiation, energy that travels in waves through space. Even when 20 phones ring at the same time with their antennae pointed at dried corn seeds, the seeds remain completely uncooked. This shows that cell phone signals carry very little energy per wave compared to the heat needed to change matter.