Unit D - Electricity

Question 1

Electric charges

Answer 1

Charged particles that exert an electric force on each other.

Question 2

Static charge

Answer 2

Charges in the surface of an object that remain fixed in one location until they are given a path to escape.

Question 3

Friction

Answer 3

The force resisting the relative motion of two surfaces in contact.

Question 4

Electron affinity

Answer 4

The tendency of a substance to hold on to electrons. Shown on the triboelectric series

Question 5

Coulomb (C)

Answer 5

The unit for electric charge named after Charles-Augustin de Coulomb and equals 6.24*10^18

Question 6

Conductivity

Answer 6

The ability of materials to hold electrons to move freely in them.

Question 7

Electric insulator

Answer 7

A solid, liquid or gas that resists or blocks the movement of electrons. Eg. wood, glass and plastic.

Question 8

Conductors

Answer 8

Materials that allow electrons to change positionsz

Question 9

Électroscope

Answer 9

An instrument that detects static chargeZ

Question 10

Electrostatics

Answer 10

The study of static electric charges.

Question 11

Charging by contact

Answer 11

When electrons transfer from the charged object to the neutral object that it touches.

Question 12

Induction

Answer 12

The movement of electrons within a substance caused by a nearby charged object without direct contact between them. The induced charge dissipates once the charged object is moved away.

Question 13

Charging by induction

Answer 13

A charged object is brought near a neutral object and then the neutral object is grounded so the previously neutral object now has the opposite charge to the charged object.

Question 14

Electrical discharge

Answer 14

When electric charges are transferred very quickly.

E.g. lightning

Question 15

Circuit

Answer 15

A complete path for electrons to flow through.

Question 16

Current electricity

Answer 16

The continuous flow of electrons in a circuit.

Question 17

Electrical load

Answer 17

A device that converts energy into another form of energy.

Question 18

Switch

Answer 18

A device that turns the circuit in or off by closing or opening the circuit.

Question 19

Battery

Answer 19

A combination of electrochemical cells made up of an electrolyte and two electrodes.

Question 20

Electrolyte

Answer 20

A liquid or paste that conducts electricity because it contains chemicals that form ions.

Question 21

Electrodes

Answer 21

Metal strips that react with electrolyte.

Question 22

Wet cell

Answer 22

An electrochemical cell that has a liquid electrolyte.

Question 23

Dry cell

Answer 23

An electrochemical cell that uses a paste.

Question 24

Potential difference/ Voltage (V)

Answer 24

The electric potential energy between two points in a circuit

Question 25

Voltmeter

Answer 25

Measures potential difference between two locations in a circuit.

Question 26

Electric current

Answer 26

The measure of the amount of electric charge that passes by a point in an electrical circuit each second.

Question 27

Direct Current (DC)

Answer 27

When the current only flows in one direction like in a battery.

Question 28

Alternating current (AC)

Answer 28

Electricity that flows backs and forth at regular intervals called cycle like the current that comes from generates an powers homes.

Question 29

Ammeter

Answer 29

Measures current in a circuit in amperes (A).

Question 30

Resistance

Answer 30

The degree to which a substance opposes the flow of electric current through it. Measures in ohms (omega symbol)

Question 31

Resistor

Answer 31

Any material that can slow current flow.

Question 32

Factors affecting the resistance of wire

Answer 32

• Material
• Temperature
• Length
• Cross- sectional area

Question 33

Transistor

Answer 33

A tiny device that acts as a switch or amplifier in a circuit.

Question 34

Series circuit

Answer 34

An electric circuit in which the components are arranged one after another in series with only one path way along which electrons flow.

Question 35

Parallel circuit

Answer 35

An electric circuit in which the parts are arranged so that electrons can flow along more than one path. There are junctions where the circuit splits into different paths and Ana interruption on one pathway doesn’t affect the other pathways in the circuit. Resistance is lessened when there are more pathways. Most electrons will follow the pathway of least resistance.

Question 36

Ohms Law

Answer 36

As long as temperature stays the same V=IR

Question 37

Short circuit

Answer 37

An accidental low resistance connection between two points in a circuit often causing excess current flow.

Question 38

Fuse

Answer 38

A safety device that has a metallic conductor with a low melting point compared to the circuits wires. If the current gets too high the metal in he fuse melts and the current flow stops. A blown fuse must be replaced as it can only be used once.

Question 39

Circuit breaker

Answer 39

Does the same as a fuse however the wire instead heats up and bend triggering a spring mechanism that turns off the flow of electricity. It can be reset once it has cooled.

Question 40

Generator

Answer 40

Transform energy of motion into an electric current.

Question 41

Percent efficiency

Answer 41

Energy out / energy in * 100%