Ohm's Law & Resistance – AP Physics 2 | ShowMeClass

Ω

Ohm's Law & Resistance

AP Physics 2 · Unit 4: DC Circuits

Learning Objectives

State and apply Ohm's law: V = IR

Understand resistivity: R = ρL/A

Interpret V vs I graphs (slope = R)

Calculate power dissipation: P = IV = I²R

Key Equations

The Ohm's Law Triangle

V = I×R · I = V/R · R = V/I

Material Resistivity

Copper: 1.7 × 10⁻⁸ Ω·m
Aluminum: 2.8 × 10⁻⁸ Ω·m
Gold: 2.4 × 10⁻⁸ Ω·m
Nichrome: 1.1 × 10⁻⁶ Ω·m
Silicon: 640 Ω·m

Ohm's LawResistancePowerAP Physics 2

V =—

I =—

R =—

P =—

V vs I (slope = R)

Solve For

Voltage V (V) 12

Current I (A) 0.5

Resistance R (Ω) 24

Wire Properties (R = ρL/A)

Length L (m) 1.0

Area A (mm²) 1.0

Material

Ohm's Law Analysis

📝 Quick Quiz▼

1. If voltage doubles and resistance stays the same, current:

Halves Doubles Stays the same Quadruples

2. The slope of a V vs I graph represents:

Power Current Resistance Energy

3. Doubling the length of a wire does what to its resistance?

Halves it Doubles it No change Quadruples it