Chapter 21 & 22 - Electromagnetism Flashcards Preview

Edexcel GCSE Physics > Chapter 21 & 22 - Electromagnetism > Flashcards

Flashcards in Chapter 21 & 22 - Electromagnetism Deck (18):
1

Name the type of transformer that converts a low-voltage supply into a high-voltage supply.

step up transformer

2

True or false? Switch mode transformers use very little power when they are switched on but no load is applied.

True

3

Does a step-down transformer increase or decrease the voltage?

Decrease

4

This is the national grid. Label Part 1

Q image thumb

Step up Transformer

5

Use for electromagnets

Electromagnets are often used to lift iron and steel scrap in scrapyards.

6

Are electromagnets a type of permenant magnet?

7

A TV requires a potential difference of 11.5V and a current of 10A. It uses a transformer to produce the correct potential difference from the mains supply. If the mains supply is 230V, what current does it provide to the transformer?

0.5A

8

Q image thumb

- D

- A parallel field

9

Explain how to produce a uniform magnetic field (3)

- Two permenant bar magnets

- Pole pieces arranged correctly e.g north facing south

- make sure magnets are the correct distance apart

10

When a plastic rod is rubbed with a cloth, the plastic rod gains ........ 

After the plastic rod has been rubbed with the cloth, the plastic rod has a ........ charge

electrons

negative

11

Electrostatic charges can be useful during paint spraying.

The droplets of paint are given the same charge as they leave the sprayer.

Explain why this is an advantage (2)

- Repel each other

- Droplets spread out

12

Droplets of paint are positivly charged.

The object being painted is given a negative charge.

Explain why this is an advantage. (2)

- Object attracts droplets

- Less paint wasted

13

Give one hazard caused by electrostatic charges and state how the risk from this hazard can be reduced (2)

- risk of spark/shock/damage

- reduce the risk by using insulation/earthing

14

15

Describe how a loudspeaker uses an electrical supply to produce sound waves [5 marks]

- There is current in the coil

- changing current produces magnetic field

- Interacts with field of permanent magnet

- Using Fleming’s LHR;

- Force on coil

- Making longitudinal waves

16

State why a metal plate used in an electromagnet device is made of iron (1)

- iron loses its magnetism quickly (not a permenant magnet)

17

Describe the construction of an electromagnet. You may draw a diagram to help your answer. (3)

- current carrying (insulated) wire

- wrapped into coil

- wrapped on iron core;

A image thumb
18

Describe the changes that allow the electromagnet to release the door when the fire alarm sounds (2)

Q image thumb

- current/ voltage reduces

- (magnetic) force holding the iron plate to the magnet no longer present