Electricity and energy

Question 1

Why do conductors conduct electricity?

Answer 1

The conductor allows the electrons to move freely (for example, a conductive material is copper)

Question 2

What is direct current?

Answer 2

Direct current is when the electrons always flow around the circuit in the same direction, form negative to positive.

Question 3

What is alternating current?

Answer 3

Alternating current is when the charges are continuously reversing, moving backwards and forwards many times per second.

Question 4

What is an electric current?

Answer 4

A region of space where charges experience an electrical force.

Question 4

What is the frequency of A.C current in the UK?

Answer 4

50 Hz

Question 5

What is 1 volt equal to?

Answer 5

1 Joule per Coulomb

Question 6

What is current?

Answer 6

Current is the flow of negative charges called electrons in a circuit.

Question 7

What is voltage?

Answer 7

The measure of electrical energy given to each coulomb in a circuit.

Question 8

At what voltage does a NPN transistor switch on?

Answer 8

When the voltage is greater than 0.7v

Question 9

At what voltage does a MOSFET switch on?

Answer 9

When the voltage is greater than 2v

Question 10

What is pressure?

Answer 10

The force applied per unit of area

Question 11

What is the UK mains supply

Answer 11

230V

Question 12

What are the two different transistors?

Answer 12

NPN transistor and MOSFET transistor

Question 12

How does an NPN transistor work?

Answer 12

By applying a voltage between the base and emitter, the transistor can be made to conduct through the emitter and collector. The voltage required to switch on the transistor is 0.7V or above. Potential divider circuits can often be used to achieve this in a variety of situations.

Question 13

What is the unit of pressure?

Answer 13

Pascal (Pa)

Question 14

Boyle’s law

Answer 14

the pressure of a fixed mass of gas at constant temperature is inversely proportional to the volume.

Question 14

Gay-Lussacs’ law

Answer 14

the pressure of a fixed mass of gas at constant volume is directly proportional to the temperature in Kelvin.

Question 15

Charle’s law

Answer 15

the volume of a fixed mass of gas at constant pressure is directly proportional to the temperature in Kelvin.

Question 16

Specific latent heat of fusion

Answer 16

the energy required to change 1 kg of a substance from a solid to a liquid without changing the temperature

Question 17

Temperature

Answer 17

a measure of the mean kinetic energy (speed) of the particles in a substance

Question 18

Absolute zero

Answer 18

-273 degree Celsius

Question 19

What is resistance

Answer 19

Resistance is the measure of the current restricted. Resistance makes the current smaller.

Question 20

3A fuse

Answer 20

= under 720 W

Question 21

13A fuse

Answer 21

= over 720 W

Question 22

what is electrical power

Answer 22

Electrical Power is the energy transferred in a period of time in a circuit.

Question 23

when does a charged particle experience a force?

Answer 23

a charged particle experiences a force in an electric field

Question 24

Switch

Answer 24

A switch allows you to complete or break a circuit

Question 24

Lamp

Answer 24

A lamp lights when current flows through it, converting electric energy into light energy

Question 25

Thermistor

Answer 25

The resistance of a thermistor will decrease as the temperature increases

Question 26

Light dependant resistor (LDR)

Answer 26

Can be used to control a circuit. The resistance goes down as the light increases

Question 27

Ammeter

Answer 27

Must be placed in series to measure the current flowing in a circuit

Question 28

Light emitting diode (LED)

Answer 28

Emits light when a current flows but only allows current to flow in one direction. Requires less energy than a lamp

Question 29

Cell

Answer 29

Supplies electrical energy to a circuit, the longer line shows the positive side

Question 30

Battery

Answer 30

A battery of cells means 2 or more cells

Question 31

DC supply

Answer 31

Supplies electrical energy to a circuit in the form of a direct current

Question 32

Ohmmeter

Answer 32

Measures resistance - must be placed in parallel with the components which are to be measured

Question 33

Voltmeter

Answer 33

Must be placed in parallel to measure the difference in electrical potential between two points

Question 33

AC supply

Answer 33

Supplies electrical energy to a circuit in the form of an alternating current

Question 34

Fuse

Answer 34

A fuse is a safety device - the metal core will melt when too much current is flowing in the circuit

Question 35

Diode

Answer 35

Only allows current to flow in one direction

Question 36

Capacitor

Answer 36

Used to store electrical charge, can be used to create a simple timing circuit, or in the flash of a camera

Question 37

Photovoltaic cell

Answer 37

Converts light energy into electrical energy, can be used as the power source in a circuit. More light will mean a greater P.D around the circuit

Question 38

Loudspeaker

Answer 38

Converts electrical energy into sound energy

Question 39

Microphone

Answer 39

Converts sound energy into electrical energy

Question 40

Motor

Answer 40

Converts electrical into kinetic energy by turning

Question 41

Variable resistor

Answer 41

A resistor, the resistance of which can be varied in the circuit, could be used for a dimmer switch

Question 42

Resistor

Answer 42

A resistor restricts the flow of current, this may be to protect other compounds