Today4/14 B-Field due to many wires HW: 4/14 “Wires” Due Thursday, 4/17 Magnetism HW delayed till Monday 4/14

I will go over it today Force on Loops and Torque on loops both due

on Wednesday 4/16 Friday and Monday are holidays! Lab: e/m ratio for electron

Lab:

e-

radius of curved path

Electron gun

V

Current carrying coils (two separate coils)

Exactly like HW due today

Magnetic Forces, WiresFind the force on wire 3 caused by wire 1 and 2.

I2 I1

I3

r

r2 r

Magnetic Forces, WiresFirst find the direction of the B field at the X. All currents are the same

I2 I1

B1 = 0 I/2 r

Bnet = B1 +B2 added as vectors

B2 = B1/ 2

r

As an example, find Bnet

B2

= Bo

B2 = Bo/ 2

B1,y = 0 B1,x = Bo

B2,y = Bo/2 B2,x = Bo/2

Bnet = Bo/ 2

45

Magnetic Forces, WiresNow find the force on wire 3.

I2 I1

I3

F = I l Bnet

Bnet

Note: Sin = 1 = 90

F = IlBo/2