Question

A microwave oven is rated at 1225 watts, meaning it delivers 1225 J of energy per second. If the microwaves in the oven have a wavelength of 12.2 cm, how many photons must the oven produce each second?

Step-by-step instructions would be most helpful! I'm studying for an upcoming exam!

Answer 1

We know that Energy, E = nhc / λ

Where

n = number of photons = ?

h = plank's constant = 6.625x 10^-34 Js

c = speed of light = 3x 10⁸ m/s

λ = wave length = 12.2 cm = 12.2x0.01 m        Since 1cm = 0.01 m

                          = 0.122 m

E = energy = 1225 J

Plug the values we get

n = E λ / (hc)

   = (1225J x 0.122m ) / ( 6.625x 10^-34 Js x 3x 10⁸ m/s )

   = 7.5x10²⁶

Therefore the number of photos produced per second is 7.5x10²⁶