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प्रश्न
What is the speed of a photon with respect to another photon if (a) the two photons are going in the same direction and (b) they are going in opposite directions?
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उत्तर
(a) In relativity, the relative speed of two objects `(v_(rel))` moving in the same direction with speeds u and v is given by `v_(rel) = (u - v)/(1-(uv)/c^2)` ...(1)
As the photons are moving with the speed of light, u = c and v = c.
On substituting the values of u and v in equation (1), we get :
`v_(rel) = 0`
Thus, relative velocity of a photon with respect to another photon will be 0, when they are going in the same direction.
(b) In relativity, relative speed of two objects moving in opposite directions with speeds u and v is given by
`v_(rel) = (u+v)/(1+(uv)/c^2)` ....(2)
We know that a photon travels with the speed of light. Therefore, u = c and v = c
On substituting the values of u and v in equation (2), we get :
`v_(rel) = c`
Thus, the relative velocity of a photon with respect to another photon will be equal to the speed of light when they are going in opposite directions.
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Which part is the photosensitive metal plate?
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Why is the polarity reversed during the procedure?
What is used to change light frequency and study its effect on emission and electron energy?
