Physics - Electromagnetism

Question 1

Which way does the magnetic field travel?

Answer 1

North to south

Question 2

What is a uniform magnetic field?

Answer 2

When magnetic field lines are the same distance apart from each other, we say that the magnetic field is uniform.

Question 3

What is magnetic flux density?

Answer 3

This is the amount of flux passing through an unit area at a right angle to the magnetic field lines. It is measured in Tesla (T).

Question 4

How do you determine from above if wires with current are coming towards you or away from you ?

Answer 4

Towards - Circle with dot in the middle.
Away - Circle with cross in the middle.

Question 5

What do the three fingers do in Fleming’s left hand rule?

Answer 5

-thuMb - Movement (force)
-Forefinger - Field (magnetic field)
-seCond finger - current

Question 6

When is Fleming’s left hand rule used?

Answer 6

Use Fleming’s left-hand rule to remember the direction of motion in an electric motor.

Question 7

What is the motor effect?

Answer 7

A current-carrying wire or coil can exert a force on a permanent magnet. This is called the motor effect.

Question 8

What is the purpose of a split ring?

Answer 8

The direction of the current must be reversed every half turn, otherwise the coil comes to a halt again. This is achieved using a conducting ring split in two, called a split ring or commutator.

Question 9

How is the induced voltage increased?

Answer 9

rotating the coil or magnet faster
using a magnet with a stronger magnetic field
having more turns of wire in the coil
having an iron core inside the coil

Question 10

What is an alternating current and a direct current in a generator?

Answer 10

Alternating - In a generator, one side of a coil moves up during one half turn and then down during the next half turn. This means that as a coil is rotated in a magnetic field, the induced current reverses direction every half turn. This is called alternating current (a.c.).

Direct - It is different from the direct current (d.c.) produced by a battery, which is always in the same direction.

Question 11

What is the difference between step up and step down transformers in terms of coils?

Answer 11

Step-up transformers have more turns on the secondary coil than they do on the primary coil.

Step-down transformers have fewer turns on the secondary coil than they do on the primary coil.