ENERGY MATTERS; Source To Consumer

Question 0

What is the size of voltage dependant on?

Answer 0

The number of turns of wire on the coil.
The strength of the magnetic field.
The speed of movement(the faster the coil is moved up and down through the magnetic field the greater the voltage).

Question 1

How can voltage be produced? (Induced voltage)

Answer 1

When a wire is moved through a magnetic field or if the conductor remains stationary and the magnetic field changes.

Question 2

What is the energy change in a dc motor?

Answer 2

Electrical to kinetic

Question 3

What is the energy change in an ac motor?

Answer 3

Kinetic to electrical

Question 4

Give two other names for ac motors

Answer 4

Dynamo or fenarator

Question 5

What is a dynamo called an alternating motor?

Answer 5

Because an alternating current is produced.

Question 6

What are the parts of a dynamo?

Answer 6

A rotor(electromagnets), stator (coils of wire) and a brush

Question 7

In a full sized ac motor instead of permanent magnets it uses rotating electromagnets called a ______.

Answer 7

In a full sized ac motor instead of permanent magnets it uses rotating electromagnets called a rotor

Question 8

What is the differnece between a full sized ac motor and smaller ac motor?

Answer 8

Commercial uses electromagnets to produce stronger magnetic field
The stator coil consists of several coils generate large current.

Question 9

What are transformers used for?

Answer 9

To change size of ac voltage

Question 10

Why are transformers used in transmitting electrical energy to homes?

Answer 10

To reduce power loss.

Question 11

How do transformers reduced power loss?

Answer 11

They reduced current by increasing voltage

Question 12

Why should current and resistance be kept low in power lines?

Answer 12

p=I*2R which shows they are related to power and should both be kept as low as possible.

Question 13

What does a transformer look like?

Answer 13

Two wires of coil (primary and secondary) wrapped around a soft iron core.

Question 14

What does the iron core do?

Answer 14

Concentrates the magnetic field.

Question 15

How is a voltage produced in a transformer?

Answer 15

Current produces a magnetic field in the primary coil. Magnetic field rapidly builds up through bot sets of coils since they are joined by the iron core, this gives a changing magnetic field in secondary coil so a voltage is produced.

Question 16

Step up transformers are used to _____ the voltage.

Answer 16

Increase

Question 17

Step down transformers are used to _____ the voltage,

Answer 17

Decrease

Question 18

A step up transformer has _____ turns on the secondary coil compared to the primary coil.

Answer 18

More

Question 19

A step down transformer has _____ turns on the secondary coil compared to the primary coil.

Answer 19

Less

Question 20

Give equation for relationship between number of turns and voltages

Answer 20

Ns/Np = Vs/Vp

Question 21

For an ideal transformer primary power =

Answer 21

Secondary power

Question 22

Therefore in an ideal transformer (voltage, no of turns current relationship)

Answer 22

Vs/Vp = Ns/Np = Ip/Is

Question 23

Why is there energy loss in real transformers?

Answer 23

Heat loss as coils have resistance
Iron core continuously magnetised and demagnetised so heat procured
Vibrates due to magnetisation/demagnetisation so energy lost as sound
Some of the magnetic file produced leaks form Enron core so does not pass to secondary.

Question 24

Why us energy lost in transmission lines?

Answer 24

Resistance of wires.

Question 25

What type of transformers are used in electricity transmission to homes?

Answer 25

Step up at power station (reduces power loss in lines) step down at homes (suitable current for homes)