# Circuit Diagrams 2

In this worksheet, students will be challenged to stretch their knowledge about circuit diagrams and increase their understanding.

Key stage:  KS 3

Curriculum topic:   Physics: Electricity and Electromagnetism

Curriculum subtopic:   Current Electricity

Difficulty level:

### QUESTION 1 of 10

Conventional symbols are used to show different components which are standard across the electrical industry. This makes it quick and easy to construct circuit diagrams - certainly a lot quicker than drawing a picture of it! It also makes it easier to construct real circuits from the drawings.

In this worksheet we'll try working out circuit diagrams from descriptions of circuits, and drawings of them, and we'll also try SERIES and PARALLEL circuits. Series circuits have all the components in a single loop so the same current goes through everything:

Parallel circuits have different branches which means that different components can be on each branch and so can be controlled individually:

Remembering that, let's see how you get on with some circuits including these principles.

Match the symbol to what it represents:

## Column B

W
motor
X
cell
Y
bulb
Z
buzzer

In this circuit what happens when the switch is closed?

bulb turns on

motor turns on

both turn on

In this circuit what happens when the switch is closed?

bulb turns on

motor turns on

both turn on

In this circuit what happens when the switch is closed?

bulb turns on

motor turns on

both turn on

Look at this circuit carefully:

Which one of the following descriptions of how the circuit works is correct?

when switch S1 is closed the buzzer sounds

when switch S2 is closed the bulb lights

when switch S1 is closed the bulb lights

when switch S2 is closed the buzzer sounds

when both switches are closed both the buzzer and the bulb turn on

when both switches are closed the buzzer sounds but the bulb is off

when both switches are closed the bulb lights but the buzzer is off

Here are four circuits:

Tick each of the bulbs that you think will be ON.

A

B

C

D

E

F

G

H

Here are three circuits with switches:

Tick which bulbs are on when the switches are open (as drawn).

A

B

C

D

E

F

Here are the same three circuits:

Imagine that the switches in all the circuits have been closed.

Tick which bulbs are on now that the switches have been closed.

A

B

C

D

E

F

Here is a description of an electric circuit:

"The circuit has two cells, two switches and two bulbs. When one switch is closed one bulb goes on and when both the switches are closed both the bulbs are on."

Which of these three circuits correctly matches the description of how this circuit works?

A

B

C

Here is a description of another electric circuit:

"The circuit has two cells, two switches, one bulb and a motor. When one switch is closed the bulb goes on and the motor turns. When both switches are closed the motor continues to spin but the bulb goes out."

Which of these three circuits correctly matches the description of how the circuit works?

A

B

C

• Question 1

Match the symbol to what it represents:

## Column B

W
bulb
X
cell
Y
motor
Z
buzzer
EDDIE SAYS
These are some of the first electrical symbols you need to learn along with switches and batteries (of several cells).
• Question 2

In this circuit what happens when the switch is closed?

both turn on
EDDIE SAYS
This is a series circuit: it's a continuous loop. That means that the current has to flow around everything once the switch is closed, so both the bulb and the motor will be on.
• Question 3

In this circuit what happens when the switch is closed?

bulb turns on
EDDIE SAYS
Now we have a parallel circuit: you can see that there are two branches with a switch and bulb on one and just the motor on the other. So, the motor will be spinning all the time (it's connected to the cell) and when you close the switch it completes that branch and allows current through the bulb.
• Question 4

In this circuit what happens when the switch is closed?

both turn on
EDDIE SAYS
We have another parallel circuit: this time the switch basically turns the cell (and so the electricity) on and off. So, close the switch and it allows current to flow through both branches and the motor and bulb both come to life. Open the switch and the current is stopped and so they both turn off.
• Question 5

Look at this circuit carefully:

Which one of the following descriptions of how the circuit works is correct?

when both switches are closed both the buzzer and the bulb turn on
EDDIE SAYS
This is an example of an AND circuit: when switches S1 AND S2 are closed the current flows around the circuit - and both the buzzer and bulb receive current so they work (it's a series circuit).
• Question 6

Here are four circuits:

Tick each of the bulbs that you think will be ON.

F
G
H
EDDIE SAYS
A and B are out: the switch is open so the cell is 'off'. C and D are out: the two cells are facing in opposite directions so no current will flow. F is on but E has been 'short-circuited': the wire below it means that all the current 'jumps' the bulb so it will receive no electricity. G and H are both on: the circuit is similar to C and D but look at the wire between bulbs and cells: that allows current to flow so it works like two separate circuits flowing in opposite directions.
• Question 7

Here are three circuits with switches:

Tick which bulbs are on when the switches are open (as drawn).

C
E
F
EDDIE SAYS
A and B are off: there is a gap in their circuit. C is connected to the cell but the branch that D is on has a gap. E and F are both connected to the cell and so are on.
• Question 8

Here are the same three circuits:

Imagine that the switches in all the circuits have been closed.

Tick which bulbs are on now that the switches have been closed.

A
B
C
D
F
EDDIE SAYS
A and B are on: their circuit is complete. Both C and D are now connected and so are on. E is now off: closing the switch has 'short-circuited' it, so the current takes the route by-passing the bulb; F is still on (although brighter - but that's another story!).
• Question 9

Here is a description of an electric circuit:

"The circuit has two cells, two switches and two bulbs. When one switch is closed one bulb goes on and when both the switches are closed both the bulbs are on."

Which of these three circuits correctly matches the description of how this circuit works?

A
EDDIE SAYS
With B closing one switch will not turn anything on: there will still be a gap. With C the bottom bulb will always be on whatever switches are open/closed. With A the top switch switches on the top bulb. The bottom switch turns on the bottom bulb.
• Question 10

Here is a description of another electric circuit:

"The circuit has two cells, two switches, one bulb and a motor. When one switch is closed the bulb goes on and the motor turns. When both switches are closed the motor continues to spin but the bulb goes out."

Which of these three circuits correctly matches the description of how the circuit works?

C
EDDIE SAYS
Closing one switch in A still leaves a gap: nothing will be on. Closing the top switch in B turns on the motor only, the bulb going on when the bottom switch closes. Closing the top switch in C completes the top half of the circuit: the motor and bulb are on. When the bottom switch is closed it 'short-circuits' the bulb which will go out; the motor is still connected to the cell, so it keeps spinning.
---- OR ----

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