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

Exam II

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

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

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

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

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

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

     PHY 2049: Physics II Self inductance

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

     PHY 2049: Physics II

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?

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

Transformers