Modern Exam #2

Question 1

Photoelectric Effect

(process described)

Answer 1

photon absorbed and electron released from target

Question 2

Photoelectric Effect

(principle relation)

Answer 2

K_max=hv-w_e

Question 3

Photoelectric effect

(precesence of other particles)

Answer 3

Electron must be bound to other particle-as an atom

Question 4

Photoelectric effect

(effective energy and wavelength region)

Answer 4

hv>w_e; energy a few electron volts and wavelength cheifly ultraviolet

Question 5

Photoelectric effect

(relative probability)

Answer 5

Less likely the higher the energy and frequency are beyond hv₀ =w_e. Goes to zero at eventually 1 MeV.

Question 6

Compton Effect

(process described)

Answer 6

Photon scattered and electron recoils in target

Question 7

Compton effect

(principle relation)

Answer 7

∆λ=(h/m₀c)(1-cosϕ)

Question 8

Compton effect

(presence of other particles)

Answer 8

electron can be free

Question 9

Compton effect

(effective energy and wavelength region)

Answer 9

Any energy, in principle. Most effective near 0.1 MeV and in long x-ray region

Question 10

Compton effect

(relative probability)

Answer 10

Less likley the higher the energy and frequency, but more likley that photoeffect beyond about 0.5 MeV.

Question 11

Pair Production

(process described)

Answer 11

photon absorbed and electron- position pair created

Question 12

Pair production

(principle relation)

Answer 12

hv=2m₀c² + (K₊ + K_-).

Question 13

pair production

(pressence of other particles)

Answer 13

Photon absorbed in encounter with heavy target nucleus

Question 14

pair production

(effective energy and wavelength region)

Answer 14

Minimum hv is 2m₀c² = 1.02 MeV. Gamma ray region or short x-ray region.

Question 15

pair production

(relative probability)

Answer 15

probability increases as energy increases beyind minimum. More effective than Compton effect beyond about 5 MeV.

Question 16

x-Ray production

(process described)

Answer 16

electron deflected in target and photon created

Question 17

x-ray production

(principle relation)

Answer 17

hv=K-K’

Question 18

x-ray production

(precesne of other particles)

Answer 18

electron deflected in encounter with heavy target nucleus

Question 19

x-ray production

(effective energy and wavelength region)

Answer 19

λ_min=hc/eV to λ=∞.

Question 20

x-ray production

(relative probability)

Answer 20

Most effective near 1.5 to 2 times λ_min.

Question 21

pair annihilation

(process described)

Answer 21

Electron and positron combine and pair of photons created

Question 22

pair annihilation

(principle relation)

Answer 22

(m₀c² +K₊) + (m₀c² +K_-) = hv₁ +hv₂

Question 23

pair annihiation

(presence of other particles)

Answer 23

Free electron and free positron, but two or more photons created

Question 24

pair annihilation

(effective energy and wavelengths region)

Answer 24

Particles can be at rest. Minimum energy of photons produced 0.511 Mev and maximum wavelength 2.43 pm.

Question 25

pair annihilation

(relative probability)

Answer 25

two-photon process more than probale than three-photon process.