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e = charge of electron = 1.6e-19
heV = Planck constant (eV⋅s) = 4.135e-15
hJ = Planck constant (J⋅s) = 6.626e-34
```3.1: Photons
a. E = heVc/λ = 1240/λ
b. N = %*(A/4πD2)*(P/E) = %*(A/4πD2)*(Pλ/hJc)
c. N' = Nλ2/λ1

```
```3.2: Photoelectric Effect
a. V = heVc/λ-Φ = 1240/λ-Φ
b. N = photons/sec = P/E = P/(hJc/λ) = Pλ/(hJc)
c. Imax = N*e
d. hf-Φ=h(f-fc) ∴ fc=Φ/heV

```
```3.3: Duane-Hunt Law
a. "Ee+Φ"
b. E = Ee*e
c. λ = heVc/Ee = 1240/Ee
d. "f"

```
```3.4: de Broglie Waves
a. λ=heV/(2m*KE/e)
b. The interference pattern is the same as for the neutrons, and the grating has the same spacing
So it is the same as λ from part (a)
c. E=heVc/λ-Φ  (keep λ in nm and heVc=1240, then convert eV to keV)
d. p=/λ  since λxray=λneutron  pxray/pneutron=1

```

`NOTE ABOUT HOMEWORK B: THESE ANSWERS MAY NOT BE CORRECT. USE THEM AT YOUR OWN RISK.HomeworkB 03------------`
Questions 1, 2, and 3 refer to the picture inside a TV set which accelerates electrons to 26 keV.
1) What is the wavelength λe of the electrons inside the set?
` λ=√1.505/KE]`
2) If photons have the same wavelength as the electrons in this TV tube, compare their momentum pγ with the momentum of the electrons pe
` pγ = h/λ = pe`
3) What is the wavelength λγ of photons which have the same energy as the electrons, Eγ=26keV?
` λ=1240/KE`
Questions 4 and 5 look like these two waves (λ1=1.5L ; λ2=L)
4) Assume that the two waves represent photons of wavelengths λ1 and λ2. Compare the energy of these two photons.
` E(λ1)=1240/λ1`
5) Assume that the two waves represent electrons of wavelengths λ1 and λ2. Compare the energy of these two electrons.
``` E1=1.505/λ12
E2=1.505/λ22
divide these two equations yields E1=.44E2```