1. Textbook: 8.2 Homework: pg. 396 # 3 – 5 pg. 402 # 1 – 3 , 10
Magnetic Forces
Textbook: 8.2
Homework: pg. 396 # 3 – 5
pg. 402 # 1 – 3 , 10
Demo: Jumping electric wires

2. Magnetic Forces
The magnetic force, FM [N], on a particle of charge q [C] moving through a magnetic field strength B [T, teslas] at a velocity v [m/s] is found by:
Where  is the angle between B and v
Pg. 396 #2, 3, 4

3. Pg 396 # 2
Determine the magnitude and direction of the magnetic force on a proton moving horizontally northward at 8.6 x 104 m/s, as it enters a magnetic field of 1.2 T directed vertically upward.
1.7 x 10^-14 N [E]

4. (c) Calculate the radius of the electron’s circular path.
An electron accelerates from rest in a horizontally directed electric field through a potential difference of 46 V. The electron then leaves the electric field, entering a magnetic field of magnitude 0.20 T directed into the page (Figure 7).
(a) Calculate the initial speed of the electron upon entering the magnetic field.
(b) Calculate the magnitude and direction of the magnetic force on the electron.
(c) Calculate the radius of the electron’s circular path.
4.0 x 10^6 m/s
1.3 x 10^-13 [down]
1.1 x 10^-4 m

5. Motion in Magnetic Fields
A charged particle moving through a constant magnetic field moves in a circular path
J.J. Thomson and the e/m ratio
e/m = 1.76 x 1011 C/kg
The Van Allen Belt (Aurora)
Particle Accelerators
Pg. 396 #4, 5