1. Electric Circuits P5.1 Static electricity P5.2 Current and voltage P5.4 Resistors in parallel P5.4 Resistors in Series P5.5 Measuring resistance Explaining Electric circuits

2. Introduction Electric Circuits

3. 21 st Century P5.1 – 5.5 Electric Circuits P5.1 Static Electricity P5.2 Current and Voltage P5.4 Resistors in series P5.4 Resistors in Parallel P5.5 Measuring resistance We will be examining the above sections and any formulas relating to them.

4. Task  Use the presentation and your own knowledge to complete the electric circuits work sheet. You will then use this sheet to complete some past paper questions.

5. Electric Circuits P5.1 Static electricity P5.2 Current and voltage P5.4 Resistors in parallel P5.4 Resistors in Series P5.5 Measuring resistance Explaining Electric circuits

6. Static Electricity Some staff felt that shock therapy was going too far to improve grades

7. What is it? Static charge is literally charge that cannot move. It is static. The charge in this case is an electric charge. The particles that move are electrons. They have a negative charge.

8. How to create it

9. Demonstration of static electricity

10. Experimenting with static charge

11. Uses of static electricity photocopiers and laser printers filtering factory smoke spray painting cars heart defibrillators

12. Electric Circuits P5.1 Static electricity P5.2 Current and voltage P5.4 Resistors in parallel P5.4 Resistors in Series P5.5 Measuring resistance Explaining Electric circuits

13. Current and Voltage

14. Definition - Current A flow of electric charge – Usually electrons Definition - Voltage  The amount of energy transferred to or from charges when they pass between two points

15. Conductors and insulators Conductors have large numbers of free electrons. This makes it easy for current to flow through them. Insulators have very few free electrons. This makes it hard for current to flow through them.

16. Measuring current We use a ammeter to measure current. The unit of current is the amp. An ammeter is wired in series.

17. Measuring voltage Voltage is measured using a voltmeter. It is measured in volts (V) a voltmeter is connected in parallel

18. Electric Circuits P5.1 Static electricity P5.2 Current and voltage P5.4 Resistors in parallel P5.4 Resistors in Series P5.5 Measuring resistance Explaining Electric circuits

19. Resistors in series

20. Resistance All electrical components have resistance. They convert the energy from the electrons into other forms of energy, often heat. If there are multiple components we need to be able to add them together. Components can be connected in series or parallel

21. Formula Components in series follow one after the other whereas components in parallel run along side by side. We can add resistors in series together with the following formula :-

22. Units The unit for resistance is the ohm.

23. Additional Notes If an component has a high resistance it converts a large amount of electrical energy as the current flows through it. i.e A lamp with a high resistance will change more electrical energy into light

24. Electric Circuits P5.1 Static electricity P5.2 Current and voltage P5.4 Resistors in parallel P5.4 Resistors in Series P5.5 Measuring resistance Explaining Electric circuits

25. Resistors in parallel

26. We also need to be able to add resistors in parallel. Parallel resistors run side by side This gives an extra route for the current to flow through Because of this the overall resistance is less than the resistance of any individual resistor

27. Formula  This is the formula for calculating the total resistance of resistors in parallel

28. Additional notes The gradient of the line in a current voltage graph represents the value of the resistance. The steeper the line the higher the resistance.

29. Electric Circuits P5.1 Static electricity P5.2 Current and voltage P5.4 Resistors in parallel P5.4 Resistors in Series P5.5 Measuring resistance Explaining Electric circuits

30. Measuring resistance

31. The size of the current flowing in a circuit depends on the voltage of the cell and the resistance of the circuit. This means that the size of the resistance can be found if we know the current and voltage in a circuit

32. Formula Voltage = Current X Resistance V=IR V = Voltage I = Current R = Resistance

33. Units Voltage is measured in volts (v) Current is measured in amps (A) Resistance is measured in ohms (Ω)

34. Current voltage graph The graph opposite shows current passing through a resistor plotted against the voltage across a resistor. As it is a straight line it shows if we double the voltage we will double the current

35. Electric Circuits P5.1 Static electricity P5.2 Current and voltage P5.4 Resistors in parallel P5.4 Resistors in Series P5.5 Measuring resistance Explaining Electric circuits