Physics
posted by mm. .
GSM networks use microwaves of 20 cm in wavelength.
The energy carried by one trillion (1012) photons of this wavelength is closest to ...
a. 10^16 Joules
b. 10^15 Joules
c. 10^14 Joules
d. 10^13 Joules
e. 10^12 Joules

find the energy in one photon using plancks constant, speed of light and wavelength.
multiply by a trillion