describe how a microwave oven works (EM waves + thermal physics)

microwaves are Electromagnetic waves with a wavelength in the order of 10^-6m (the prefix for 10^-6 is micro, just as 10^-3 is milli). these short wavelength waves have a high energy due to equation E=hc/λ, showing that energy is inversely proportional to wavelength. The high energy waves incident on the food source, cause molecules on the surface to vibrate. This is due to the exchange of energy, where the energy of the photon has transferred to kinetic energy of the food molecule (mostly water H20 molecules). These surface molecules will then collide with their neighbour molecules, transferring kinetic vibrational energy to their neighbours. This process, known as conduction, disperses kinetic energy throughout the food source. Kinetic energy of a group of many molecules in a system is the definition of thermal energy. therefore, as more microwaves interact with the food, it gains more kinetic energy, and thus gains more thermal energy - the food heats up.  

AE

Related Physics A Level answers

All answers ▸

What is an electron volt?


A 10m long uniform beam is pivoted in its centre. A 30kg point mass is placed on one end of the beam. Where must a 50kg mass be placed in order to balance the beam?


Give a brief description of the Big Bang and describe its link to cosmic microwave background radiation.


The electric potential energy of two protons is 1.0MeV. Calculate their separation