# Homework Help: How many photons does it emit?

1. Sep 11, 2007

### GravityGirl

a 1-kW raido transmitter operates at 880kHz. How many photons per second does it emit?

Power=work/time
Power=change in KE/time

f=1/T
T=1/880kHz

so 1 kw=change in KE/1.136x10^-6

change in KE=.00136 J

i don't know if i am doing this right. please point me in the right direction.

2. Sep 11, 2007

### GravityGirl

should i use the equation E(light)=hc/wavelength?

what is h in this equation?

3. Sep 11, 2007

### GravityGirl

should i use the equation E(light)=hc/wavelength?

what is h in this equation?

4. Sep 11, 2007

### fikus

The energy of photon is:

$$E=h\nu = hc/\lambda$$, h is Planck's constant (6.6x10^-34 Js or 4.1x10^-15 eVs)

So everything that you should do is to divide the power of your transmitter (1 kW) with that energy E.