Electricity

Question 1

What are circuit diagrams?

Answer 1

a map of electric circuits

Question 2

What is the purpose of circuit diagrams?

Answer 2

• stylised way of drawing circuit, easier to follow

- study and develop new circuits

Question 3

What are closed and open circuits?

Answer 3

A closed circuit is a complete circuit and an open circuit has a break in it

Question 4

What is a series circuit and what happens to bulbs?

Answer 4

• only one pathway for electrons to flow
• if one bulb blows, they all go out
• more bulbs, less glow

Question 5

What is a parallel circuit and what happens to bulbs?

Answer 5

• several pathways for electrons to flow
• if one bulb blows, the remaining stay on
• all bulbs maintain their glow

Question 6

Define what a power supply, load and conduction path are?

Answer 6

• the power supply is the electricity source e.g. battery, generator, outlet
• the load is the component that consumes electrical energy and converts it to other forms like heat and light
• the conduction path is the route where current flows through the circuit

Question 7

current is ________________ to voltage

Answer 7

directly proportional

Question 8

What is electric current?

Answer 8

the flow of electrons around a circuit

Question 9

What is current measured in and what is used to measure it?

Answer 9

amperes (amps) are measured by ammeters

Question 10

The higher the current, the …

Answer 10

• faster an object moves

- increase no. of electrons flowing through circuit per second

Question 11

Which circuit do you measure current?

Answer 11

• current is the same throughout circuit in series

- current is different in each loop of parallel circuit

Question 12

What is an electrical circuit?

Answer 12

a closed loop that is the path for the transfer of electrical energy from battery or power point to electrical component.

Question 13

What does an electrical component do?

Answer 13

converts electrical energy into other forms e.g. light, heat, sound kinetic

Question 14

What 3 things does a electrical circuit need:

Answer 14

• source of electrical energy aka power supply with positive and negative terminals.
• component to convert electrical energy to other forms of energy aka load
• wires aka conduction path connecting component/s to electrical source to form loop

Question 15

What two things make circuits safer?

Answer 15

• switches control the flow of energy

- fuses and safety switches break the circuit, cutting supply, when they detect large currents

Question 16

What is voltage?

Answer 16

• aka as potential difference

- amount of energy or ‘push’ a power supply gives to electrons

Question 17

What are voltages measured in and what is used to measure it?

Answer 17

volts (V) are measured by voltmeters

Question 18

As current passes through load, what does voltage do?

Answer 18

drops

Question 19

Which circuit do you measure voltage?

Answer 19

• in series voltage is shared

- in parallel every loop has same voltage

Question 20

name voltages given in the following electrical sources: AA battery, car battery, power points in home.

Answer 20

1.5V, 12V and 240V respectively

Question 21

What is resistance?

Answer 21

• the measure of how easy it is for electricity to pass through a conductor
• a material’s opposition to the flow of electric current

Question 22

describe what happens in resistance.

Answer 22

the electrons collide with the particles that make up the conductor it is passing through. it obstructs the flow of electrons and causes the no. of electrons passing to decrease. electrons lose their energy from friction experienced during collision which is converted to other forms of energy.

Question 23

What is resistance measured in?

Answer 23

measured in ohms represented by greek letter omega (basically the libra sign)

Question 24

Resistance depends on what three things?

Answer 24

wire length: longer the wire, more resistance
wire thickness: thinner the wire, greater the resistance
kind of metal: nichrome provides more resistance

Question 25

Where are resistance wires used?

Answer 25

provide heat to kettles, toasters, ovens and may be coiled to fit in small spaces like light bulbs.

Question 26

What do resistors do?

Answer 26

Resistors lower the current passing through circuit and convert to other forms of energy

Question 27

What is Ohm’s Law?

Answer 27

• describes the relationship between current, voltage and resistance
• formula is V = IR

Question 28

What is a conductor (why does it work)?

Answer 28

• transmits electricity with minimal wastage
• example is copper wires
• their atom’s outer electron are held loosely

Question 29

What is an insulator?

Answer 29

• prevents leakage of current and electric shock

- plastic insulation/covering around wires

Question 30

What are electrons and how do they move?

Answer 30

• electrons are subatomic particles with a negative charge
• move because of electromagnetic force - opposites attract, alike repel
• electrons at negative terminal are attracted to positive terminal when they are connected

Question 31

What is a short circuit?

Answer 31

low resistance alternative path that bypasses resistor

Question 32

What happens as a result of a short circuit?

Answer 32

• appliance won’t work

- large currents cause electrical shock and overheating wires cause electrical fires.

Question 33

What are fuses and circuit breakers?

Answer 33

safety mechanisms that cut off power supply when they detect dangerously large currents

Question 34

What are fuses made from?

Answer 34

thin (therefore, high resistance) wires that overheat and burn, breaking circuit.
- must be replaced

Question 35

What are circuit breakers?

Answer 35

triggered by large currents to cut off supply through a switch.