Biot-Savart Law & Magnetic Field – AP Physics C E&M | ShowMeClass

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Biot-Savart Law & Magnetic Field

AP Physics C E&M · Unit 5: Magnetism

Learning Objectives

Apply Biot-Savart law: dB = (mu0/4pi) I dl x r / r3

Calculate B at center/axis of circular loop

Calculate B from a straight wire segment

Superpose fields from multiple wires

Key Equations

Geometry Guide

Infinite wire: B = μ0I/(2πr)

Loop center: B = μ0I/(2R)

Loop axis: B = μ0IR2/[2(R2+z2)^(3/2)]

Colors

Current direction

B-field lines

Field magnitude

Probe point

Biot-SavartMagnetismB-field

|B| =-

I =-

probe =-

|B| vs DISTANCE

Source Geometry

Current I (A) 5

Loop Radius R (cm) 10

Probe distance (cm) 5

Wire separation d (cm) 6

Wire 2 Current

Display

Biot-Savart Analysis

Quick Quiz▼

1. B from an infinite straight wire at distance r is:

mu0*I/(2*pi*r) mu0*I*r/(2*pi) mu0*I/(4*pi*r2) mu0*I*R/(2*r)

2. B at the center of a circular loop of radius R is:

mu0*I/(2*R) mu0*I/(2*pi*R) mu0*I*R/2 mu0*I/(4*pi*R2)

3. Two parallel wires with same-direction current:

Attract each other Repel each other No force Rotate