Explore 1: Laundry Machine. Electricity – Potential Dividers

1.

Recording Notice
This lesson is
being recorded

2.

King’s Interhigh Logo

3.

Explore 1: Laundry Machine
Electricity – Potential Dividers

4.

Objective
Understand how the potential along a uniform current-carrying
wire varies with the distance along it.
Understand the principles of a potential divider circuit and
understand how to calculate potential differences and
resistances in such a circuit.
Be able to analyse potential divider circuits where one
resistance is variable including thermistors and light dependent
resistors (LDRs).

5.

Starter – Multiple Answer
What will increasing the resistance of R 1 change?
12V
A. The voltage across R 1
B. The voltage across R 2
C. The current through R 1
D. The current through R 2
R1 = 34 Ω
• A, B, C and D
• One’s voltage will increase, two’s will decrease.
• The current will decrease by the same amount for
both.
SLIDE:
5
R2 = 54 Ω

6.

Activity: Washing line mission
Your mission is to design an automatic
washing line.
It must sense:
• Heat
• Rain (lack of)
• Sunshine
To put the laundry out it must be:
• Dry
• Sunny and/or warm
Thermistor
SLIDE:
6
LDR
Moisture detector

7.

Logic Gates
You have these logic gates to help you.
Red means there is a current.
OR
AND
T
NOT
AND
OR
AND
OR
SLIDE:
7
AND
NOT
T
OR

8.

Blank slide to draw on in Breakouts
SLIDE:
8

9.

SLIDE:
9
Out?
OR
Sunny
AND
Warm
M
Rain
Solution
0
0
0
0
0
0
1
1
0
1
0
1
0
1
1
1
1
0
0
0
1
0
1
0
1
1
0
0
1
1
1
0

10.

Plenary
Fill in the blanks
1
• A potential divider is a part of a circuit with two components.
2
• Typically, one component is variable
resistor.
• The other is often a thermistor or a LDR. 3
• Together they control an output voltage.
4
SLIDE:
10

11.

Objective
Understand how the potential along a uniform current-carrying
wire varies with the distance along it.
Understand the principles of a potential divider circuit and
understand how to calculate potential differences and
resistances in such a circuit.
Be able to analyse potential divider circuits where one
resistance is variable including thermistors and light dependent
resistors (LDRs).
SLIDE:
11

12.

Explore 2: Exam Practice I
Electricity – Potential Dividers

13.

Objective
Understand how the potential along a uniform current-carrying
wire varies with the distance along it.
Understand the principles of a potential divider circuit and
understand how to calculate potential differences and
resistances in such a circuit.
Be able to analyse potential divider circuits where one
resistance is variable including thermistors and light dependent
resistors (LDRs).

14.

Starter
Write any points or questions you have relating to potential dividers.
Points
SLIDE:
14
Questions

15.

Q1
SLIDE:
15

16.

Q1
SLIDE:
16

17.

Q2
SLIDE:
17

18.

Q2
SLIDE:
18

19.

Q3
SLIDE:
19

20.

Q3
SLIDE:
20

21.

Q3
SLIDE:
21

22.

Q3
SLIDE:
22

23.

Plenary
Play taboo with words and phrases related to this topic….
SLIDE:
23

24.

Objective
Understand how the potential along a uniform current-carrying
wire varies with the distance along it.
Understand the principles of a potential divider circuit and
understand how to calculate potential differences and
resistances in such a circuit.
Be able to analyse potential divider circuits where one
resistance is variable including thermistors and light dependent
resistors (LDRs).
SLIDE:
24

25.

Explore 3: Practical
Electricity – Potential Dividers

26.

Objective
Build a virtual potential divider.
SLIDE:
26

27.

Starter
Why are potential dividers useful?
What two things do they allow you to do?
• They allow a device to work automatically
and respond to an outside stimulus, like
temperature.
• You can set the conditions for the response
action: example - at what temperature the
heating comes on
SLIDE:
27

28.

Phet
• Build this circuit.
• Adjust the resistors and
note the effect on
voltage.
SLIDE:
28

29.

Alternative / Extension
• This sim is a bit more
fiddly but does
allow you do more.
SLIDE:
29

30.

Plenary
Watch the 6.45 min onwards.
How is its metaphor useful for
Potential Dividers?
• The more one step drops the
marble the less height there is
for the other component.
Electric Circuits: Basics of the voltage and current laws
9.47 min
SLIDE:
30

31.

Objective
Understand how the potential along a uniform current-carrying
wire varies with the distance along it.
Understand the principles of a potential divider circuit and
understand how to calculate potential differences and
resistances in such a circuit.
Be able to analyse potential divider circuits where one
resistance is variable including thermistors and light dependent
resistors (LDRs).
SLIDE:
31

32.

Explore 4: Exam Practice II
Electricity – Potential Dividers

33.

Objective
Understand how the potential along a uniform current-carrying
wire varies with the distance along it.
Understand the principles of a potential divider circuit and
understand how to calculate potential differences and
resistances in such a circuit.
Be able to analyse potential divider circuits where one
resistance is variable including thermistors and light dependent
resistors (LDRs).
SLIDE:
33

34.

Starter
Can you work out the resistances?
SLIDE:
A
10 Ω
B
21 Ω
C
74 Ω
D
83 Ω
34

35.

Q1
SLIDE:
35

36.

Q1
SLIDE:
36

37.

Q2
SLIDE:
37

38.

Q2
SLIDE:
38

39.

Q3
SLIDE:
39

40.

Q3
SLIDE:
40

41.

Q4
SLIDE:
41

42.

Q4
SLIDE:
42

43.

Q5
SLIDE:
43

44.

Q5
SLIDE:
44

45.

Q6
SLIDE:
45

46.

Q6
SLIDE:
46

47.

Q7
SLIDE:
47

48.

Q7
SLIDE:
48

49.

Q7
SLIDE:
49

50.

Plenary
SLIDE:
50

51.

Objective
Understand how the potential along a uniform current-carrying
wire varies with the distance along it.
Understand the principles of a potential divider circuit and
understand how to calculate potential differences and
resistances in such a circuit.
Be able to analyse potential divider circuits where one
resistance is variable including thermistors and light dependent
resistors (LDRs).
SLIDE:
51

52.

Lesson complete!
See you next lesson