Chapt 13 Magnetism

Question 1

Direction of field of a current-carrying wire

Answer 1

Right-hand rule

Point the thumb in the direction of the current. The direction of the curled fingers indicates field direction.

Question 2

Magnetic field of a current-carrying wire

Answer 2

B = ((permeability of free space) x I)/(2 pi x r)

Question 3

Permeability of free space

Answer 3

4 pi x 10^7 (Tm)/A

Question 4

Force of a charge moving in a magnetic field

Answer 4

Fb : qvB

(mv^2)/r : qvB

Question 5

Movement of a positive charge moving in a magnetic field

Answer 5

Right-hand rule

Thumb: v

Fingers: B

The direction the palm pushes: Fb

Use left hand for negative charges

Question 6

Force of wire in an external magnetic field

Answer 6

Fb : ILB

I: wire
L: field
B: external magnetic field

Question 7

Magnetic forces on two current-carrying wire

Answer 7

Fb directed towards each other if direction of current in the two wires are the same.

Fb directed against each other if direction of current in the two wires are different

Question 8

Magnetic flux

Answer 8

Magnetic flux : Change of BA

Question 9

Electromagnetic induction

Answer 9

Coil and magnet are either moving away from each other of moving toward each other

Question 10

Emf

Answer 10

Emf : (change of BA)/time

Question 11

Lenz’s law

Answer 11

1. If the magnetic flux is increasing, then the current flows in a way so that its magnetic field counters the increase the magnetic field
2. If the magnetic flux is decreasing, then the current flows in a way so that its magnetic field increases the magnetic field