Answer to Question #120598 in Atomic and Nuclear Physics for ethan

Question

Can you help me verify these answers?
1. An X-ray photon collides with a stationary electron. How does the frequency of the scattered photon compare to the frequency of the photon before being scattered?
A. The new frequency is higher.
B. The new frequency is lower
C. The frequency stays the same.
D. The scattered photon has no frequency, as it acts like a particle
==> A?
2. When light shines on a metal cathode in a vacuum tube
A. electrons may be ejected
B. electrons are always ejected
C. protons may be ejected
D. protons are always ejected
==> B?
3.Einstein’s theory of photons explained the experimental results of the photoelectric effect by saying
A. the electrons had quantized energy levels
B. the light’s frequency determines the photon’s energy, and the energy must be more than the work function
C. the electron’s position is not known, only the probability of where to find it
D. the frequency of the light has to be more than a certain, threshold frequency
==> B?

Answer 1

1. Incorrect; the wavelength after scattering becomes higher, which means that the frequency (according to v=c\λ) becomes lower.
2. Incorrect. The Work Function is the energy required to remove an electron from metal. If the wavelength of light is too long, this light cannot cause electrons to leave the metal.
3. Correct.