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# Quantum question watch

1. When an electron annihilates a positron, two photons are produced, each with an energy of 511keV. Calculate the frequency of each photon.
2. (Original post by harryabel62)
When an electron annihilates a positron, two photons are produced, each with an energy of 511keV. Calculate the frequency of each photon.

E = hf.

Since we know E (511keV x 2 = 1022keV), and we know h (6.67 x 10^-34), we can work out f by rearranging:

f = E/h.

Can you do it now?
3. (Original post by Kyx)
E = hf.

Since we know E (511keV x 2 = 1022keV), and we know h (6.67 x 10^-34), we can work out f by rearranging:

f = E/h.

Can you do it now?
I am pretty sure you do not multiply it by 2 as it says in the question "EACH PHOTON has an energy of 511Kev"
4. (Original post by Kyx)
E = hf.

Since we know E (511keV x 2 = 1022keV), and we know h (6.67 x 10^-34), we can work out f by rearranging:

f = E/h.

Can you do it now?
Also it's not 6.67 is 6.63 for planks constant
5. (Original post by Kyx)
E = hf.

Since we know E (511keV), and we know h (6.63 x 10^-34), we can work out f by rearranging:

f = E/h.

Can you do it now?
Fixed

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