# Electromagnetic devices

In this lesson will explore how direct current (DC) is produced by dynamos, comparing the construction of a dynamo to that of a generator and also compare the construction and operation of a loudspeaker and microphone.

Quiz:

# Intro quiz - Recap from previous lesson

Before we start this lesson, let’s see what you can remember from this topic. Here’s a quick quiz!

## Question 9

Q1.Which sentence below describes electromagnetic induction?

1/9

Q2.What is the word that describes when a potential difference is made in a coil?

2/9

Q3.Which scientist first discovered electromagnetic induction?

3/9

Q4.Which of these would not cause the direction of the potential difference to reverse when using a coil and a magnet to demonstrate the generator effect?

4/9

Q5.Which term refers to when a conductor and wire move across each other?

5/9

Q6.In which of these situations will there not be an induced potential difference?

6/9

Q7.Which direction will the magnetic field made by the induced current be?

7/9

Q8.Decide if each statement below is true or false.
A potential difference will be induced if the magnet is held stationary the coil.
An electric current will flow if the ends of the coil are connected to an external circuit.
A potential difference will not be induced if the magnet is moved up and down inside the coil.
An induced current generates a magnetic field that opposes the original change, either the movement of the conductor or the change in magnetic field.

8/9

Q9.Which of the following will increase the size of the induced potential difference

9/9

Quiz:

# Intro quiz - Recap from previous lesson

Before we start this lesson, let’s see what you can remember from this topic. Here’s a quick quiz!

## Question 9

Q1.Which sentence below describes electromagnetic induction?

1/9

Q2.What is the word that describes when a potential difference is made in a coil?

2/9

Q3.Which scientist first discovered electromagnetic induction?

3/9

Q4.Which of these would not cause the direction of the potential difference to reverse when using a coil and a magnet to demonstrate the generator effect?

4/9

Q5.Which term refers to when a conductor and wire move across each other?

5/9

Q6.In which of these situations will there not be an induced potential difference?

6/9

Q7.Which direction will the magnetic field made by the induced current be?

7/9

Q8.Decide if each statement below is true or false.
A potential difference will be induced if the magnet is held stationary the coil.
An electric current will flow if the ends of the coil are connected to an external circuit.
A potential difference will not be induced if the magnet is moved up and down inside the coil.
An induced current generates a magnetic field that opposes the original change, either the movement of the conductor or the change in magnetic field.

8/9

Q9.Which of the following will increase the size of the induced potential difference

9/9

# Video

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# Worksheet

These slides will take you through some tasks for the lesson. If you need to re-play the video, click the ‘Resume Video’ icon. If you are asked to add answers to the slides, first download or print out the worksheet. Once you have finished all the tasks, click ‘Next’ below.

Quiz:

# Electromagnetic Devices

## Question 9

Q1.Which device produces alternating current?

1/9

Q2.Which device produces direct current?

2/9

Q3.Which type of commutator do alternators have

3/9

Q4.In dynamos and alternators, how will the coil be lined up with the magnetic field when the induced potential difference is highest?

4/9

Q5.What is the main difference between a dynamo and an alternator?

5/9

Q6.Why does the direction of the potential difference not reverse in a dynamo?

6/9

Q7.Match up the effect used to the device.
Alternator
Dynamo
Loudspeaker
Microphone

7/9

Q8.How is a sound wave made by a loudspeaker?

8/9

Q9.How is an alternating current made by a microphone?

9/9

Quiz:

# Electromagnetic Devices

## Question 9

Q1.Which device produces alternating current?

1/9

Q2.Which device produces direct current?

2/9

Q3.Which type of commutator do alternators have

3/9

Q4.In dynamos and alternators, how will the coil be lined up with the magnetic field when the induced potential difference is highest?

4/9

Q5.What is the main difference between a dynamo and an alternator?

5/9

Q6.Why does the direction of the potential difference not reverse in a dynamo?

6/9

Q7.Match up the effect used to the device.
Alternator
Dynamo
Loudspeaker
Microphone

7/9

Q8.How is a sound wave made by a loudspeaker?

8/9

Q9.How is an alternating current made by a microphone?

9/9

# Lesson summary: Electromagnetic devices

### Time to move!

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Chair yoga

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