P3.3 Keeping Things Moving

Question 0

A coil of wire is also known as?

Answer 0

Solenoid

Question 1

Where is a field around a wire?

Answer 1

It circulates the wire

Question 2

What’s the field around a solenoid like?

Answer 2

Like a bar magnet field

Question 3

Why will a conductor increase the field?

Answer 3

It gets magnetised as well

Question 4

What’s the motor effect?

Answer 4

A wire carrying a current in a magnetic field feels a force ( electrical - kinetic)

Question 5

How is force increased?

Answer 5

Increasing the magnetic field strength, higher current ( and more length of wire)

Question 6

The conductor will not have a force is it’s _____ to the magnetic field?

Answer 6

Parallel

Question 7

How can you find the direction?

Answer 7

Flemmings left hand rule

Question 8

What does the thumb show in Flemmings left hand rule?

Answer 8

Force

Question 9

What does the index finger show in Flemmings left hand rule?

Answer 9

Field

Question 10

What does the 3rd finger show in Flemmings left hand rule?

Answer 10

Current

Question 11

How can direction be reversed?

Answer 11

AC

Reverse the magnetic field

Question 12

How are transformers made?

Answer 12

If a electrical conductor cuts through a magnetic field a p.d is made
AC in the primary coil makes a changing field in the iron core so it constantly cuts through the secondary coil

Question 13

If a magnet is moved in a coil what happens?

Answer 13

A p.d is induced across the ends of the coil

Question 14

What do step up transformers look like and do?

Answer 14

Less to more coils

Increase voltage

Question 15

What do step down transformers look like and do?

Answer 15

More to less coils

Voltage decreases

Question 16

How do you find voltage in each coil?

Answer 16

V^p/V^s=N^p/N^s

Question 17

What would current and voltage be if it was 100% efficient?

Answer 17

V^p x I^p = V^s x I^s

Question 18

Why are transformers not 100% effective?

Answer 18

They make noise

Question 19

What’s the different with a switch mode transformer?

Answer 19

Works at 50-200Hz rather than >50Hz
Lighter and small
Use little power 
No load applied
Higher failure risk
Eg. Mobile phones