1. Equipment Calculators
See if students can remember the measurement of energy

2. 4 6 8 Date and title: Calculating current and charge
Lesson intentions:
How much charge flows around a circuit?
23 April, 2019
S t e p s
t o
S u c c e s s
Learning outcomes:
Identify circuit components from their symbols.
Calculate the charge transferred by a steady current in a given time.
Perform a range of calculations, including rearrangement of the equation Q = It. 4 6 12 8
Key words: Current, Charge, Amps, Coulombs

3. Calculating current and charge
Identify circuit components from their symbols.
Calculate the charge transferred by a steady current in a given time.
Perform a range of calculations, including rearrangement of the equation Q = It. 4 6 8

4. Draw and label these symbols
Starter
Draw and label these symbols
Cell
(NOT BATTERY!)
Ammeter
Lamp
Students need to be aware of these symbols.
They should know atleast half
Ensure you run through the difference between a cell and a battery (Battery is 2 or more cells joined together, it can look like picture 6 or two of picture 1 ’stuck’ together)
Switch
Voltmeter
Battery

5. Bigger picture Topic Potential difference and resistance
Component characteristics
Current and charge
Series Circuits
Topic
Electric Circuits
Parallel Circuits

6. CURRENT I SI Unit: Amps A Symbol: Measured in: Key info
Recap key information

7. Current (I)
Current is the rate of flow of charge (i.e. how much charge is flowing past per second)
So current is measured in Coulombs per second (C/s)
BUT the C/s has its
own particular name:
the ampère, amp, or A.
Recap

8. So how do we work it out?
If current is measured in Coulombs per second (C/s)…
What might the equation to Calculate it be?
Have students try to put this together on their own first.. Those who are better at maths should get this quickly

9. Q t I Current = Charge / Time (in A) (in C) (in s) or I = Q / t
Walk through how to use the triangle, also why the equation works.
Using the bike chain analogy the amount of charge going past a certain point per second.. Increase the current buy pedalling faster etc.

10. Example questions on current
Charge (C)
Current (A)
Time (s) 5 2
0.4 1 20
0.5 50
250 3 60
A circuit is switched on for 30s with a current of 3A. How much charge flowed?
During electrolysis 6A was passed through some copper chloride and a charge of 1200C flowed. How long was the experiment on for?
A bed lamp is switched on for 10 minutes. It works on a current of 0.5A. How much charge flowed?
Questions posed in ‘Charge and Current.ppt’.

11. Example questions on current
Charge (C)
Current (A)
Time (s) 10 5 2
0.4 1 20
0.5 40 50
0.2
250
180 3 60
A circuit is switched on for 30s with a current of 3A. How much charge flowed?
During electrolysis 6A was passed through some copper chloride and a charge of 1200C flowed. How long was the experiment on for?
A bed lamp is switched on for 10 minutes. It works on a current of 0.5A. How much charge flowed?

12. Example questions on current
Charge (C)
Current (A)
Time (s) 10 5 2
0.4 1 20
0.5 40 50
0.2
250
180 3 60
A circuit is switched on for 30s with a current of 3A. How much charge flowed? Q = I x t = 3 x 30 = 90 C
During electrolysis 6A was passed through some copper chloride and a charge of 1200C flowed. How long was the experiment on for?
A bed lamp is switched on for 10 minutes. It works on a current of 0.5A. How much charge flowed?

13. Example questions on current
Charge (C)
Current (A)
Time (s) 10 5 2
0.4 1 20
0.5 40 50
0.2
250
180 3 60
A circuit is switched on for 30s with a current of 3A. How much charge flowed? Q = I x t = 3 x 30 = 90 C
During electrolysis 6A was passed through some copper chloride and a charge of 1200C flowed. How long was the experiment on for? t = Q / I = 1200 / 6 = 200 s
A bed lamp is switched on for 10 minutes. It works on a current of 0.5A. How much charge flowed?

14. Example questions on current
Charge (C)
Current (A)
Time (s) 10 5 2
0.4 1 20
0.5 40 50
0.2
250
180 3 60
A circuit is switched on for 30s with a current of 3A. How much charge flowed? Q = I x t = 3 x 30 = 90 C
During electrolysis 6A was passed through some copper chloride and a charge of 1200C flowed. How long was the experiment on for? t = Q / I = 1200 / 6 = 200 s
A bed lamp is switched on for 10 minutes. It works on a current of 0.5A. How much charge flowed? Q = I x t = 0.5 x 600 = 300 C

15. Example question 4
Calculate the current when 4C passes a point in 8 seconds

16. Example question 5
An ammeter is records a current of 8A. Calculate how much charge is passing through the ammeter in 10 seconds.

17. Task
What is the current when 20C of charge pass through an ammeter in 2minutes?
A battery can produce 20A of current. How much charge does it discharge in 30s?
Another battery can produce a charge of 30A. How long will this battery be running before it has discharge the same amount of charge as the battery in Q2?
A car engine requires a battery that can produce a current of 40A to start. A mechanic places a battery that can discharge 100C in 30s into a car. Will this battery be good enough to start the car? Why?
For the question above, how much charge would the battery have to discharge in 30s to start the engine?
Further to this lesson can be supported with Physics textbook pages 52 and 53

19. What are the key points to remember from Friday’s lesson
Knowledge Check
What are the key points to remember from Friday’s lesson
Students mini mind map in their books the key points about current and charge.