1. Voltage
state that the e.m.f. of a source of electrical energy is measured in volts
show understanding that e.m.f. is defined in terms of energy supplied by a source in driving charge round a complete circuit
state that the potential difference across a circuit component is measured in volts
use and describe the use of a voltmeter

2. Voltage
The v_____ is a measure of how big a push the e_______ are given as they leave the cell or b_____. The bigger the voltage, the bigger the p___.
The cell, battery or p____ s_____ produces the voltage.
oltage
lectrons
attery
ush
ower upply
lamps

3. Voltage
There are two types of voltage e.m.f. and potential difference (p.d.).
A cell or power supply increases the amount of energy in a circuit.
The energy given to each unit of chargeas it passes arond the circuit, is called the e.m.f.
This can be thought of as the electrical pressure pushing the current around a circuit.
When the electrical current flows through a component like a bulb, it loses energy.
For example in a bulb light energy is given out. The difference in the energy of each unit of charge is known as the potential difference.
lamps

4. Series circuit

5. Measuring the voltage Measure the voltage using a voltmeter.
Connect the voltmeter “across” the component
i.e. one lead to either side.
This is the potential difference across the component.
If there are no components attached to a power supply the e.m.f. is equal to the potential difference measured.

6. Set up the two circuits shown:A. B.
Now measure the voltage across each component in your circuits
What do you notice about your readings?

7. Energy and charge
We can express a relationship between charge, energy and potential difference mathematically using the equation:
Energy = Charge x Voltage
E=QV
Charge measured in Coulombs (C)
Energy measured in Joules (J)
Voltage measured in Volts (V)

8.   x E Q Formula triangles
Formula triangles help you to rearrange formula, the triangle for E=QV is shown below:
Whatever quantity you are trying to find cover it up and it will leave you with the calculation required.
…and you are left with the sum…
So if you were trying to find charge, Q…..
Q = E V E  
…you would cover Q up… Q V x

9. Formula triangles
This is a flash movie – click on the letter you want to cover to start the animation

10. A charge of 100 C is delivered at a potential difference of 5V
A charge of 100 C is delivered at a potential difference of 5V. How much energy is delivered?
E = QV
= 100 C x 5 V
= 500 J
What is 500J in KJ?
0.5 kJ
In an examination you must always give the units.
If you do not you will lose a mark.

11. To do P
Answer questions 1&2

12. Name this circuit symbol.V
Ammeter
Switch
Bulb
Voltmeter 

13. What component is used to measure electrical current?
Switch
Resistor
Ammeter
Voltmeter 

14. Which component changes electrical energy into light energy?
Bulb
Switch
Cell
Battery 

15. Which component is a store of chemical energy?
Bulb
Battery
Switch
Resistor 

16. Which of these materials is not a conductor of electricity?
Water
Graphite
Lead
Wood 

17. Progress check
state that the e.m.f. of a source of electrical energy is measured in volts
show understanding that e.m.f. is defined in terms of energy supplied by a source in driving charge round a complete circuit
state that the potential difference across a circuit component is measured in volts
use and describe the use of a voltmeter