Photon: (ai) Suppose a photon has position 4-vector x^= (ct, x) = (3 times 10^8,
ID: 2075186 • Letter: P
Question
Photon: (ai) Suppose a photon has position 4-vector x^= (ct, x) = (3 times 10^8, -3 times 10^8) at t = 1 s, write down its position 4-vector at t = 3 s. Assume the photon is moving in the positive x direction. (aii) The photon has zero rest mass so we need to be careful when writing down the 4-momentum of the photon. Take a photon to have energy E, write down the 4-momentum p^of the photon in terms of E. Assume the photon is moving in the positive x direction. Maxwell's equations: (bi) Obtain Ampere-Maxwell law from partialdifferential _v F v = mu_0 J^mu. (bii) Obtain the remaining 2 Maxwell's equations from partialdifferential^sigma F^mu v + partialdifferential^mu F^v sigma + partialdifferential^v F^sigma mu = 0. Meaning of K^0: For K^mu = qF^mu v uv, work out the 0-component in terms of time t and ordinary velocity u vector and explain its physical meaning.Explanation / Answer
3a, the phton is moving in the x-direction
hence dispalcment in x -direction in 3 s = 3.0e+8 * 3 = 9.0e+8 m
x-positon after 3s = -3.0e+8 + 9.0e+8 = 6.0e+8
position vector after 3s = (9.0e+8, 6.0e+8)
ii) momentum four-vector for photon ( E, pc)