Electromagnets

Question 1

How does the national grid work?

Answer 1

High current and low voltage leads to high resistance. This means cables get very hot and lose energy whilst transporting electricity. To stop this, current is kept voltage is kept high and current is kept low in cables

Question 2

National grid changes in current and voltage?

Answer 2

Power station-> high current, low voltage
Cables-> low current, high voltage
Consumer -> high current, low voltage

Question 3

Step up?

Answer 3

Voltage increases

Question 4

Power equation

Answer 4

Current(amps)X potential difference(volts)= power

Question 5

What is power?

Answer 5

Energy transferred per second

Question 6

Primary and secondary coil?

Answer 6

Must have the same amount of energy transferred as energy cannot be created or destroyed.

Question 7

Step down?

Answer 7

Voltage decreases( less turns on secondary coil)

Question 8

What is A.C?

Answer 8

Alternating current, current can flow in both directions in the wire

Question 9

Motor effect?

Answer 9

When a current-carrying wife is in the presence of a megnaguc field and experiences a force

Question 10

Force equation

Answer 10

Force = B X I X L

Newtons/amps/tesla X current X length of wire(metres)

Question 11

Change in direction of current means?

Answer 11

Change in direction of magnetic field

Question 12

Increase current results in?

Answer 12

Increase strength of magnetic field

Question 13

What is an electromagnet?

Answer 13

A magnet that runs on electricity

Question 14

Permanent magnet?

Answer 14

Always magnetic, attracts magnetic materials

Question 15

What does it means if lines are closer together in a magnetic field?

Answer 15

Magnetic field is stronger

Question 16

Earth’s magnetic field?

Answer 16

Made of electric currents in molten outer core- made of iron and nickel

Question 17

How to change strength of electromagnet?

Answer 17

Change current change coils around the iron coil

Question 18

Left hand rule?

Answer 18

Thumb = movement of force
First finger= magnetic field
Middle finger= current

Question 19

Factors affect size of force?

Answer 19

Current
Strength of magnet
Angle between wire and field

Question 20

Force depending on wire angle?

Answer 20

Force is highest when wire is perpendicular to magnetic field lines
Force is 0 when it’s parallel

Question 21

Generator effect?

Answer 21

Moving a wire through a magnetic field produces current

Question 22

Transformers equation

Answer 22

Vs X Is = Vp X Ip

Voltage in secondary coil X current in secondary coil is equal to voltage in primary coil X current in primary coil

Question 23

Density equation

Answer 23

M/v