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`“Life is like riding a bicycle.  To keep your balance you must keep moving.”–Albert Einstein`

## Monday, March 24, 2008

### AP Physics B – A Free-Response Question (for practice) involving Compton Scattering

Here is a typical free-response question for your practice:

An X-ray photon of energy 31000 eV proceeds in the positive X-direction. It collides with a free electron at rest. After the collision the electron moves in the positive X-direction with a momentum greater than that of the X-ray photon. In the process, the wave length of the X-ray photon is changed by an amount dλ = 0.0486 Ǻ.

(a) What is the direction of motion of the photon after the collision? Justify your answer.

(b) Will the wave length of the photon decrease or increase? Justify your answer.

(c) Determine the wave length of the photon before collision.

(d) Calculate the kinetic energy transferred (by the photon) to the electron.

This question carries 10 points which may be divided among parts (a), (b), (c) and (d) as 3+2+2+3. Answer this question. I’ll be be back soon (with the answer, for your cofidence).