Physics - Magnetism Flashcard

Question 1

What is the definition of electromagnetism?

Answer 1

Electromagnetism is the phenomenon whereby electric currents produce their own magnetic fields.

Question 2

What does electric current produce around a wire?

Answer 2

A magnetic field.

Question 3

How are magnetic field lines represented around a wire?

Answer 3

As concentric circles around the wire.

Question 4

What rule helps determine the direction of the magnetic field based on current direction?

Answer 4

The right hand rule.

Question 5

How do you apply the right hand rule?

Answer 5

Curl your fingers in the direction of the current and your thumb points in the direction of the magnetic field.

Question 6

What happens to the magnetic field when two wires are joined to form a flat circular coil?

Answer 6

The magnetic fields combine to form a single magnetic field running through the center of the coil.

Question 7

What is a solenoid?

Answer 7

A coil of wire
(created by adding more turns to a coil.)

Question 8

What are the characteristics of an electromagnet?

Answer 8

An electromagnet is created using electricity and is only magnetic as long as current flows through the wire.

Question 9

What are methods to increase the strength of an electromagnet?

Answer 9

• Increase the current flowing through the solenoid
• Increase the number of turns in the coil
• Decrease the length of the coil
• Add an iron core to the solenoid

Question 10

What happens to iron when a solenoid is switched on?

Answer 10

Iron becomes an induced magnet.

Question 11

What is the generator effect also known as?

Answer 11

Electromagnetic induction.

Question 12

What is induced when a wire bent into a coil is moved through a magnetic field?

Answer 12

A potential difference.

Question 13

What occurs to the potential difference when the wire stops moving?

Answer 13

It disappears.

Question 14

What is needed to generate current?

Answer 14

A complete circuit.

Question 15

How can a larger potential difference be induced?

Answer 15

• Change the strength of the magnetic field
• Move the wire or magnets more quickly
• Shape the wire into a proper coil

Question 16

What does movement of a magnet into and out of a coil induce?

Answer 16

A potential difference.

Question 17

What are magnetic materials?

Answer 17

Any object that can be influenced by a magnetic field and has the potential to become a magnet.

Question 18

What are key magnetic elements?

Answer 18

• Nickel
• Cobalt
• Iron
• Steel

Question 19

What defines a permanent magnet?

Answer 19

Produces its own magnetic field all the time.

Question 20

What defines an induced (temporary) magnet?

Answer 20

Only has a magnetic field temporarily.

Question 21

What is the force between a permanent and induced magnet?

Answer 21

Always attractive.

Question 22

What is the motor effect?

Answer 22

When a current-carrying wire is placed in a magnetic field, it experiences a force.

Question 23

What rule helps determine the direction of the force in the motor effect?

Answer 23

Fleming’s Left-Hand Rule.

Question 24

What happens to a coil with a current flowing through it in a magnetic field?

Answer 24

It experiences opposite forces on each side, causing it to rotate.

Question 25

What is the role of the split ring commutator in an electric motor?

Answer 25

Swaps the positive and negative connections every half turn.

Question 26

What do step-up transformers do?

Answer 26

Increase voltage to around 400,000 volts to minimize energy loss.

Question 27

What do step-down transformers do?

Answer 27

Decrease voltage to 230 volts to make it safe for household use.

Question 28

What is Faraday's Law?

Answer 28

A change in magnetic field will induce an electromotive force (emf) in a coil.

Question 29

What is the stroking method in magnetization?

Answer 29

A magnetic material is stroked repeatedly in one direction with a permanent magnet.

Question 30

What is the single touch method in magnetization?

Answer 30

A single strong stroke with a permanent magnet along the length of the material.

Question 31

What is the double touch method in magnetization?

Answer 31

Using two magnets with opposite poles moving towards the ends of the material simultaneously.

Question 32

What does the right-hand rule for solenoids determine?

Answer 32

The direction of the magnetic field produced by a current-carrying solenoid.

Question 33

What happens to the magnetic field inside a solenoid?

Answer 33

It is strong and uniform.

Question 34

What occurs at the center of a current-carrying circular loop?

Answer 34

The magnetic field is perpendicular to the plane of the loop.

Question 35

What is the characteristic of the magnetic field outside a solenoid?

Answer 35

Weak and nearly zero.