Chapter 16 Flashcards Preview

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Flashcards in Chapter 16 Deck (21)
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1
Q

What is a magnetic field?

A

A region where a force is exerted on magnetic materials.

2
Q

Where to flux lines come from and go to?

A

North to south.

3
Q

What do your thumb and fingers represent using the “right-hand rule”?

A

Thumb-Current and Fingers-Magnetic field.

4
Q

Will a wire carrying current in a magnetic field experience a force?

A

Yes.

5
Q

Explain how to use Fleming’s left-hand rule.

A

First finger points in the direction of the external magnetic Field (N to S). SeCond finger points in the direction of the Current. ThuMb points in the direction of the force (in which the Motion takes place.

6
Q

Force on current carrying wire=

A

ILB (B=Magnetic flux density)

7
Q

What does 1B=

A

The force on one metre of wire carrying a current of one amp at right angles to the magnetic field.

8
Q

What is Magnetic Flux Density measured in?

A

Teslas

9
Q

What are the units for Teslas?

A

Wb/m²

10
Q

What happens when a conducting rod moves perpendicular to a magnetic field? What is this process called?

A

The electrons in the rod will experience a force which causes them to accumulate at one end of the rod. Electromagnetic induction.

11
Q

What do changes in magnetic Flux induce?

A

An electromotive force.

12
Q

What is Magnetic Flux Density?

A

The strength of the magnetic field per unit area.

13
Q

What is Magnetic Flux?

A

The magnetic flux density multiplied by the area.

14
Q

What is Magnetic Flux Linkage?

A

The product of the Flux and the number of coils in the wire.

15
Q

What is Lenz’s law?

A

The induced e.m.f is always in such a direction as to oppose the change that caused it.

16
Q

How do transformers work?

A

By electromagnetic induction.

17
Q

Why aren’t transformers 100% efficient?

A

Loses energy in the form of heat because of resistance and eddy currents.

18
Q

What is “Permeance”?

A

Similar to conductance. Its the amount of flux induced for a given number of current turns. Higher permeance=greater amount of flux induced.

19
Q

What do Dynamos do?

A

Convert kinetic energy into electrical energy.

20
Q

What do Transformers do?

A

Change the size of the voltage for an A.C. current.

21
Q

What is Faraday’s law?

A

The induced e.m.f is directly proportional to the rate of change of flux linkage.