Hello, dear friend, you can consult us at any time if you have any questions, add WeChat: daixieit

PHYS1120 Exam III review

Things to remember for PHYS1110: algebra, trig (sin, cos, ..)

vector math, especially vector addition, Fnet = ma problems, free-body diagrams

Exam1 and Exam2 Material : E-fields, Gauss's Law, voltage, capacitors, circuits.

Last part of Chapter 26 : RC circuits

• Voltage across a capacitor is always

• An uncharged capacitor has ΔV= 0 , acts like a wire, as short (does not resist the flow of current).

• A fully charged capacitor has I = 0, acts like an open switch.

• time constant is

Ch. 27 Magnetic fields

• This is the definition of B .

• When both E-field and B-field are present:

• Motion of charge in magnetic field and in velocity selector.

• force and torque on a current loop

Ch. 28 Sources of Magnetic fields

• Currents cause magnetic fields (B-fields)

• Biot-Savart Law: (Know what all the symbols mean)

• Ampere's Law:

Be able to use Ampere to derive

▪ B-field outside long straight wire:

▪ B-field inside long wire of radius R:

▪ B-field inside solenoid:

(No need to memorize these formulas; know how to derive them)

• "right-hand rule 2": point thumb in direction of straight thing, fingers curl in sense of circular thing.

• B-field is a vector:

• parallel currents attract; anti-parallel currents repel

• Gauss's Law for B-fields: Magnetic monopoles do not exist.

• field of a solenoid, permanent magnet acts like solenoid

Ch. 29 Faraday's Law

• Faraday's Law: An emf (= battery voltage) is caused by a changing magnetic flux:

magnetic flux

Be able to use Faraday's Law to derive E-field inside or outside a solenoid.

• Lenz's Law: Iinduced creates Binduced in direction that opposes the change in flux.

• Motors and generators

• Eddy current forces always oppose the motion

To prepare for any exam:

• Study my online lecture Notes.

• Review Concept Tests, MP problems, and Tutorial HW. (Read question and try to remember reasoning that gets to the answer)

• Prepare your formula sheet. Prioritize: which are the important equations?

• Take the practice exam.

• It is no good to memorize answers. You have to understand and remember how you got the answers.