RL Circuit Transient Response – AP Physics C E&M | ShowMeClass

RL

RL Circuit Transient Response

AP Physics C E&M · Unit 4: Circuits

Learning Objectives

Derive i(t) for RL charging and discharging

Calculate time constant tau = L/R

Analyze V_R and V_L during transients

Calculate energy stored: U = 1/2 LI2

Key Equations

Time Constant

τ = L/R

At t = τ: i reaches 63.2% of max
At t = 5τ: i reaches 99.3% (~steady state)

Colors

i(t) current

V_R(t)

V_L(t)

U_L(t) energy

RL CircuitInductorTransient

t =-

i =-

V_R =-

V_L =-

U_L =-

i(t)

V(t)

U(t)

All

Phase

EMF (V) 12

R (ohms) 10

L (mH) 50

Speed 1x

RL Analysis

Quick Quiz▼

1. The time constant of an RL circuit is:

RC L/R R/L LR

2. During RL charging, V_L at t=0 equals:

0 EMF EMF/2 IR

3. Energy stored in an inductor is:

LI 1/2 LI2 LI2 1/2 LV2