Electricity

Question 1

Static electricity

Answer 1

is a build up of electric charge that can occur on good insulators e.g. polythene and perspex rods

Question 2

Polythene rod

Answer 2

A polythene rod gains electrons if a woollen cloth is rubbed on it (becomes negatively charged)

Question 3

Perspex rod

Answer 3

• A perspex rod loses electrons if it is rubbed by a woollen cloth (becomes positively charged)
• Unlike charges attract each other, like charges repel each other
• Earthing occurs when a charged object loses its charge to the earth through a conductor

Question 4

What is an electric current

Answer 4

• An electric current is caused by the flow of electrons through a good conductor such as a metal
• A good insulator does not allow electric current to flow

Question 5

Closed circuits

Answer 5

• A closed circuit is needed for the current to flow
• If there is a break in a circuit then the current wont flow and the electrical energy can’t get through

Question 6

Batteries

Answer 6

• Energy provided by a battery or power pack is needed to move the current around the circuit
• The battery pumps electrons from its negative end around a circuit
• The electrons travel all the way around and are attracted back to the positive end of the battery

Question 7

Potential difference

Answer 7

• The difference in electrical pressure between the positive and negative ends is called the Potential Difference
• Whenever there is a potential difference electricity will flow
• This potential difference is known as Voltage and is measured in volts

Question 8

Resistance

Answer 8

• Resistance is the opposition to the flow of electrons. The unit is the Ohm (Ω), and it is measured using an Ohmmeter
• If a Resistor is placed in an electric circuit, it will slow down the flow of electrons

Question 9

Bulbs in series

Answer 9

• Like the bulb on a christmas tree, what happens if one blows?
• The same amount of current flows through each bulb in the series
• The voltage is split up, depending on the size of the bulb
• If they are the same size bulbs, then the voltage is split evenly

Question 10

Bulbs in parallel

Answer 10

• The lights in your house are connected in parallel, as are car head lights
• If your bedroom light blows, is the kitchen light affected?
• The current is split between the bulbs, if they are the same size, then the current is split evenly
• The same voltage flows through each bulb