Electromagnetic induction

Question 1

Who:

Established that current and magnetism are related?

Answer 1

Oersted and Ampere

Question 2

Who:

Established that moving magnetic fields can induce a current?

Answer 2

Faraday and Henry

Question 3

What is:

Electromagnetic induction?

Answer 3

When electric current is generated by changing magnetic fields.

Question 4

List:

Faraday’s experiments:

Answer 4

• Using a stationary coil and a magnetic
• Using 2 coils, moving the one with current
• Using 2 stationary coils, one with a tapping key.

Question 5

Formula:

Magnetic flux?

Answer 5

Flux = BAcosθ

Unit: Wb or Tm^2

Question 6

List:

Faraday’s laws of induction:

Answer 6

• Whenever the magnetic flux associated with a circuit changes, and emf is induced.
• Emf = change in flux/change in time

Question 7

Formula:

EMF ?

Answer 7

ε = - dΦ/ dt

Question 8

Fill in:

When the north pole approaches the coil —-

Answer 8

—- that end becomes north

( and when the south pole leaves the coil, that end becomes north)

Question 9

Fill in:

Lenz’s law is a consequence of the conservation of—-

Answer 9

—- energy

Question 10

Formula:

Motional EMF?

Answer 10

ε = Blv

For a coil/disc: 1/2 BWR^2

Question 11

Formula:

Mutual/self inductance?

Answer 11

M or L = NΦ / i

Unit: Henry or Wb/A

Question 12

Formula:

For EMF in terms of M or L?

Answer 12

ε = - L or M x di/dt

Question 13

Formula:

Mutual inductance of a solenoid:

Answer 13

μ0n1n2Al

Question 14

Formula:

Self inductance of a solenoid:

Answer 14

μ0n^2Al

Question 15

Formula:

Mutual inductance of conc. coils:

Answer 15

= μ0 pi (r1)^2 / (r2)

r2 >r1

Question 16

Formula:

Instantaenous EMF for an AC generator:

Answer 16

ε = BANWSinWT

Question 17

Formula:

Maximum EMF for an AC generator:

Answer 17

ε= BANW

Question 18

Formula:

Avg. EMF for an AC generator:

Answer 18

0