1. PHY 2049: Physics II
Tutoring Center is open in room NPB 1215, M-F 12:00AM -4:00PM. It is free.

2. Exam II

3. hitt
A square loop of current-carrying wire with edge length a is in the xy plane, the origin being at its center. Along which of the following lines can a charge move without experiencing a magnetic force?
A. x = 0, y = a/2 B. x = a/2, y = a/2
C. x = a/2, y = 0 D. x = 0, y = 0,
E. x = 0, z = 0

4. Ch. 30 Induction and Inductance
Magnetic Flux
Faraday’s Law of Induction
Lenz’ law
Inductors
Self and Mutual
Series RL circuits
Magnetic Energy

5. PHY 2049: Physics II Faraday’s Law: Electric generators
Electric guitars
Engine starters, cars, scooters etc.
Induction stoves
The basic idea: When a magnetic field changes in time, it produces an electric field

6. PHY 2049: Physics II Some concepts: Faraday’s law Lenz’ law:
the kickback

7. PHY 2049: Physics II
Things that matter
Pole
Direction of motion

8. PHY 2049: Physics II
Seen From left
Switch turned on
Switch turned off

9.     
PHY 2049: Physics II
Self inductance

10. PHY 2049: Physics II Self inductance NΦB = Li
    
PHY 2049: Physics II
Self inductance
NΦB = Li
Analogously mutual inductance.

11.     
PHY 2049: Physics II

12. PHY 2049: Physics II When the switch is first thrown
    
PHY 2049: Physics II
When the switch is first thrown
The inductors block any current. All current flows through the middle resistance. I = V/R
Later, the inductors are all closed and the current is then I = 3V/R.
How much time does it take for the current to rise?

13. PHY 2049: summary Faraday’s Law Lenz’ Law the minus sign
    
PHY 2049: summary
Faraday’s Law
V = -dΦ/dt
Lenz’ Law the minus sign
Inductance self and mutual
V = L dI/dt
Time evolution of current
Time constant t = L/R

14. Transformers