P213 - Electromagnetic induction

Question 1

What are the two ways a PD can be induced?

Answer 1

• Changing magnetic field through electrical conductor
• Electrical conductor moving in magnetic field

Question 2

How can you induce a bigger potential difference in an electrical conductor?

Answer 2

More coils
Making magnetic field change more rapidly

Question 3

When is induced PD the highest?

Answer 3

when the edges of the coil are moving at a 90 degree angle to the magnetic field lines.

Question 4

How do dynamos produce DC currents?

Answer 4

In a dynamo, a coil of wire rotates and the magnet is fixed.
The coil rotates. This generates (produces) a potential difference in one direction.
The split-ring commutator reverses the direction of the current every half-turn of the coil. This makes sure that the current is always moving in the same direction to keep the coil rotating.
The potential difference is largest when the coil and the magnetic field are parallel.
When the coil ‘cuts’ across the magnetic field at the fastest rate.
The potential difference is zero when the coil is perpendicular (at right angles) to the magnetic field.
When the coil does not ‘cut’ the field lines at all.

Question 5

What can transformers do?

Answer 5

Change the voltage in wires carrying alternating currents.

Question 6

What are the 3 main parts of a transformer?

Answer 6

Primary coil
Secondary coil
Iron core

Question 7

What are transformers split into?

Answer 7

Step-up transformers and step-down transformers.

Question 8

What coil in a step up transformer has more turns?

Answer 8

The secondary coil
The pd is stepped up

Question 9

What coil in a step down transformer has more turns?

Answer 9

The primary coil
The pd is stepped down

Question 10

What are the principles of a Transformer?

Answer 10

Alternating potential difference
Changing magnetic field
Secondary coil potential difference

Question 11

What are transformers used for?

Answer 11

Transformers are used to increase the voltage of electricity, so it can be transmitted long distances through cables.

Question 12

How many voltages are step up transformers used to increase it up to?

Answer 12

400,000V

Question 13

How many volts is electricity generated at?

Answer 13

15,000V

Question 14

What is the rate of energy transferred to components equal to?

Answer 14

Current multiplied by the potential difference