Summary Derivations - OCR Module 4, Electrons, Waves, and Photons (A-Level)

Module 4
Electrons, Waves, and photons
OCR A A-level physics



•
Electron Drift Velocity I = nave

Rz
• Potential Divider ✓out
= Vin
R, t Rz




• Power Equations Starting from P= ¾ into P= IV etc



• Resistors in series RT = Ri + R2 + Rs ....



• Resistors in parallel _Ip, = 1, + Rz OR Rt - (¼ + &)'


• Snell's haw ① = Sin" (¾)



• Young's Double Slit ✗ = 9

• Diffraction Grating dsina = nx


• De Broglie's Wavelength ✗ =! = ½p

, e- e- é e- e-
A e-
é
é é é
T




Deriving I = nave Q = It
- Ne (electron
n = number of charge carriers per m³ N= nv numbers)

nV = Total number of charge carriers
NVe = Total charge (Q = male)


① Q = It ① = Ne
Ne = IE


② Ne-It and N=nv
nve = It
rearrange to get I= nve

cross-sectional area ✗ length
③ change V to V= AL

⟂ = Male
∈

④ Sub in v= ¼ (= VE


I = nAu t e
∈ cancels out


- = have