P15 - Electromagnetism

Question 1

Like poles?

Unlike poles?

Answer 1

Like poles repel

Unlike poles attract

Question 2

Any iron or steel object?

Answer 2

Can be magnetised or demagnetised

Question 3

Region around magnet?

Answer 3

Magnetic field

Question 4

Magnetic field lines?

Answer 4

Lines of force

Question 5

Line of force direction?

Answer 5

Always n-s pole

Question 6

Induced magnetism?

Answer 6

Placing an unmagnetised magnetic material in a magnetic field

Question 7

Iron and steel are what type of magnet?

Answer 7

Permanent magnet

Question 8

Solenoid?

Answer 8

A long insulated coil of wire

Question 9

Shape of magnetic field lines in solenoid?

Answer 9

Each is a complete loop

Question 10

Electromagnet?

Answer 10

A solenoid where insulated wire is wrapped around iron bar

Question 11

Reversing the current…

Answer 11

Reverses the magnetic field lines

Question 12

Uniform magnetic field?

Answer 12

one in which the magnetic field lines are parallel

Question 13

Magnetic field lines around a wire?

Answer 13

circles centred on the wire in plane perpendicular to the wire

Question 14

E. Magnetic flux density?

Answer 14

force = megetic flux density x current x length             
(N)     =             (T, tesla)         x       (I)     x   (M)

Question 15

D. Motor effect?

Answer 15

When a current is passed along a wire in a magnetic field, and the wire is not parallel to the lines of the magnetic field, a force is exerted on the wire by the magnetic field

Question 16

D. Magnetic flux density?

Answer 16

the measure of the strength of a magnetic field - (B is the symbol and is measured in teslas, T)

Question 17

Flemming’s left hand rule?

Answer 17

a rule that gives the direction of the force on a current-carrying wire in a magnetic field according ti the directions of current and field

Question 18

D. Split ring commutator?

Answer 18

Metal contacts on the coil of a direct current motor that connects the rotating coil continuously to its electrical power supply

Question 19

Why does the coil spin when current is passed through it?

Answer 19

• a force acts on each side due to the motor effect

- `the force on one side is in the opposite direction of the force on the other side