Magnetism

Question 1

What happens when a magnet is moved towards a coil of wire or solenoid connected to an ammeter?

Answer 1

The ammeter will deflect, showing that current is flowing through the coil.

Question 2

How can a solenoid be imagined in relation to a bar magnet?

Answer 2

The solenoid can be imagined as a bar magnet with oriented poles.

Question 3

What occurs when the poles of the solenoid are oriented to resist the motion of a magnet?

Answer 3

The solenoid will repel the magnet.

Question 4

What letters represent the poles of a solenoid?

Answer 4

N (north) and S (south).

Question 5

What does the direction of current in the solenoid represent when arrows are added to the letters N and S?

Answer 5

The arrows represent the current direction in the solenoid.

Question 6

What direction does the current pass around the ‘north pole’ end of the solenoid?

Answer 6

Anticlockwise.

Question 7

What direction does the current pass around the ‘south pole’ end of the solenoid?

Answer 7

Clockwise.

Question 8

What is Faraday’s Law of Electromagnetic Induction?

Answer 8

Faraday’s Law states that a change in magnetic field within a closed loop induces an electromotive force (EMF) in the wire.

Question 9

True or False: Faraday’s Law only applies to stationary magnetic fields.

Answer 9

False

Question 10

Fill in the blank: The induced EMF is proportional to the rate of change of __________.

Answer 10

magnetic flux

Question 11

What is the formula for calculating induced EMF according to Faraday’s Law?

Answer 11

EMF = -dΦ/dt

Question 12

What does the symbol ‘Φ’ represent in Faraday’s Law?

Answer 12

Magnetic flux

Question 13

Multiple choice: Which of the following factors does NOT affect the induced EMF?

Answer 13

The color of the wire

Question 14

True or False: A stronger magnetic field will produce a greater induced EMF.

Answer 14

True

Question 15

Short answer: What is Lenz’s Law?

Answer 15

Lenz’s Law states that the direction of induced current will oppose the change in magnetic flux that produced it.

Question 16

Fill in the blank: If the magnetic flux through a loop increases, the induced current will flow in a direction that __________ the increase.

Answer 16

opposes

Question 17

What is the unit of magnetic flux?

Answer 17

Weber (Wb)

Question 18

Multiple choice: Which scenario will produce a larger induced EMF?

Answer 18

A rapidly changing magnetic field

Question 19

True or False: Induced EMF can only be produced by moving magnets.

Answer 19

False

Question 20

What is the relationship between the number of turns in a coil and induced EMF?

Answer 20

The induced EMF is proportional to the number of turns in the coil.

Question 21

Fill in the blank: Faraday’s Law can be applied in __________ generators.

Answer 21

electric

Question 22

Short answer: What is the significance of the negative sign in Faraday’s Law?

Answer 22

The negative sign indicates the direction of the induced EMF opposes the change in magnetic flux.

Question 23

What happens to induced EMF if the area of the loop is increased while the magnetic field remains constant?

Answer 23

The induced EMF increases.

Question 24

True or False: Faraday’s Law is a fundamental principle of electromagnetism.

Answer 24

True

Question 25

Multiple choice: Faraday's Law is used in which of the following applications?

Answer 25

Electric transformers

Question 26

Fill in the blank: The induced EMF causes an __________ in the circuit.

Answer 26

electric current

Question 27

Short answer: How does changing the orientation of a coil in a magnetic field affect induced EMF?

Answer 27

Changing the orientation can either increase or decrease the magnetic flux, thus affecting the induced EMF.

Question 28

What is the role of a conductor in Faraday's Law?

Answer 28

A conductor allows the induced EMF to cause an electric current.

Question 29

True or False: Faraday's Law applies to both AC and DC circuits.

Answer 29

True

Question 30

Fill in the blank: Faraday's Law is essential in the working of __________ motors.

Answer 30

electric

Question 31

What is the primary application of Faraday's Law in everyday technology?

Answer 31

Electric power generation

Question 32

Multiple choice: Which device operates based on Faraday's Law?

Answer 32

Electric generator

Question 33

What is Faradays Law

Answer 33

The magnitude of the induced emf is directly proportional to the rate of change of magnetic flux linkage

Question 34

How can you increase the induced EMF in a coil?

Answer 34

1- move magnet faster 2- use stronger magnet 3- increase no. of turns on coil

Question 35

What happens to the induced emf if the coil has more turns?

Answer 35

EMF is greater as each additional turn of wire cuts more lines of magnetic flux

Question 36

Two laws of electromagnetic induction

Answer 36

1- whenever there is a change in magnetic flux relative to the coil, an emf is induced 2- the magnitude of the emf is directly proportional to rate of change of magnetic flux linkage

Question 37

If magnetic field lines are closer what is stronger?

Answer 37

Magnetic field

Question 38

What is the magnetic flux density?

Answer 38

“Strength of the field” Force per unit current per unit length on a current-carrying conductor placed in a mag field perpendicular to field lines

Question 40

What pole does current go anticlockwise

Answer 40

North

Question 41

What pole does current go clockwise

Answer 41

South

Question 42

Define the motor effect

Answer 42

When a current carrying wire is placed within a magnetic field it experiences a force perpendicular to the flow of current and the field lines which push it out of the field

Question 43

Give the formula relating magnetic force, flux density, current, length and angle between field and conductor

Answer 43

F=BILsinx

Question 44

Why do charged particles move in a circular orbit in a magnetic field?

Answer 44

Force is always perpendicular to velocity of a particle so they end up being forced into a circular path of motion therefore they undergo centripetal acceleration with the magnetic force represented the centripetal force

Question 45

Using r=mv/BQ explain what affects radius and how

Answer 45

Mass and velocity increasing will increase the radius, Flux density and charge increasing will decrease the radius

Question 46

Define magnet flux

Answer 46

The product of the flux density and the area that is perpendicular to the field lines

Question 47

Define magnetic flux linkage

Answer 47

Product of the magnetic flux and number of turns on a coil =BxAxN

Question 48

State Lenz Law

Answer 48

Induced emf is always in a direction so as to oppose the change that caused it