Electromagnetic Induction Current Induced in a Straight Conductor - - PDF document

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Electromagnetic Induction Current Induced in a Straight Conductor Current Induced in a Loop of Wire Faradays Law of Induction Magnetic Flux Lenzs Law Homework Current Induced in a Straight

SLIDE 1

Electromagnetic Induction

Current Induced in a Straight Conductor Current Induced in a Loop of Wire Faraday’s Law of Induction Magnetic Flux Lenz’s Law Homework

SLIDE 2

Current Induced in a Straight Conductor

A conductor of length ✁ moves with velocity ✂ ✄✆☎

through a uniform magnetic field

✂ ✄✞✝ ✟ ✠ perpendicular to ✂ ✄ ☎

.

A current is induced in the conductor due to the

magnetic force on charges in the conductor.

Serway/Jewett Figure 23.1

SLIDE 3

Current Induced in a Loop of Wire

A current is induced in the loop when a magnet is

moved toward the loop.

No current is induced in the loop when the magnet

is stationary.

When the magnet is moved away from the loop. A

current is induced in the opposite direction.

Serway/Jewett Figure 23.2

SLIDE 4

Faraday’s Law of Induction

The induced emf in a circuit is equal (except for a

negative sign) to the rate at which the magnetic flux through the circuit changes with time.

✡ ☛ ✂ ☞✍✌ ✎ ☞✑✏ ☛ ✂ ☞ ☞✑✏✓✒ ✂ ✄✞✝ ✔ ☞ ✂ ✄✖✕ The SI unit of magnetic flux is the weber (Wb): 1

Wb = 1 T.m

✗ The negative sign is an indication of the direction of

the induced emf.

When applying Faraday’s law to a coil with ✘

turns, an emf appears in every turn and these emfs add.

✡ ☛ ✂ ✘ ☞✍✌ ✎ ☞✑✏

SLIDE 5

Magnetic Flux

The magnetic flux ☞✍✌ ✎

through a differential ele- ment of area

☞ ✂ ✄✖✕

is given by

✂ ✄ ✝ ✔ ☞ ✂ ✄✙✕

=

✝ ☞ ✕ ✚✜✛✣✢✥✤

.

Note that the vector ☞ ✂ ✄ ✕

is perpendicular to the sur- face.

Serway/Jewett Figure 23.4

SLIDE 6

Example A 1000-turn coil is 10.0 cm in diameter. What emf is developed across the coil if the magnetic field through the coil is reduced from 6.00 T to 0.00 in (a) 1.00 s, (b) 0.100 s, and (c) 0.100 ms?

dA B i

✌ ✎✧✦ ☛ ✒ ✂ ✄ ✝ ✟★✔ ☞ ✂ ✄✙✕ ☛ ✒ ✝ ✟ ☞ ✕ ☛ ✝ ✟✩✕ ☛ ✝ ✟✫✪ ✬✭ ✭ ✭✮ ☞ ✯ ✰✲✱ ✱ ✱ ✳ ✗ ✌ ✎✴✦ ☛ ✵✷✶✹✸✻✺✣✺✽✼ ✾ ✪ ✬✭ ✭ ✭ ✮ ✺✹✸❀✿❁✺✣✺❃❂ ✯ ✰✲✱ ✱ ✱ ✳ ✗ ☛ ❄❅✸❇❆❈✿ ❉ ✿❁✺✑❊ ✗ ❋

✎ ☛ ✌ ✎ ❍ ✂ ✌ ✎ ✦ ☛ ✺ ✂ ❄❅✸❇❆❈✿ ❉ ✿❁✺✑❊ ✗ ❋

✎ ☛ ✂ ❄❅✸❇❆❈✿ ❉ ✿❁✺ ❊ ✗ ❋ ✵✷■❏✾❑✡ ☛ ✂ ✘

✎

☛ ✂ ✵▲✿❁✺✣✺✣✺▼✾ ◆ ✂ ❄❅✸❇❆❈✿ ❉ ✿❁✺ ❊ ✗ ❋P❖ ✿✣✸✻✺✣✺❘◗ ✡ ☛ ❄❙❆❈✸❚✿❱❯ ✵ ❋ ✾ ✡ ☛ ❄❙❆❈✿❱❯ ✵❳❲❨✾ ✡ ☛ ❄❙❆❈✿❱❩❬❯

SLIDE 7

Lenz’s Law

The induced current will appear in such a direction

that it opposes the change that produced it.

That is, the induced current is in a direction such

that the induced magnetic field attempts to maintain the original flux through the loop.

Serway/Jewett Figure 23.16

SLIDE 8

Homework Set 23 - Due Fri. May 28

Read Sections 23.1 & 23.3 Answer Question 23.1 Do Problems 23.1, 23.3 & 23.6