Electricity Test

Question 1

current electricity

Answer 1

the controlled flow of electrons

Question 2

Static electricity

Answer 2

Electrons gather in one place and move randomly in all directions

Question 3

Load

Answer 3

Converts electrical energy into other usable forms

Question 4

Energy source

Answer 4

Provides electrical energy (e.g. battery).

Question 5

Switch

Answer 5

Opens or closes the circuit to control the flow of electrons

Question 6

Electrical wires

Answer 6

Pathway for electrons to travel.

Question 7

short circuit

Answer 7

An accidental connection between two points in a circuit that bypasses the load.

Question 8

What are the hazards of a short circuit

Answer 8

Electrical shock

Electrocution

Fires

Question 9

What is an electric cell

Answer 9

A portable device that converts chemical energy into electrical energy using a chemical reaction.

Question 10

Primary cell

Answer 10

Cannot be recharged (non-reversible reaction).

Question 11

Secondary cell

Answer 11

Can be recharged (reversible chemical)

Question 12

Direct current

Answer 12

Electrons flow in one direction (from batteries).

Question 13

Alternating current

Answer 13

Electrons switch direction back and forth (from generators, wall outlets).

Question 14

How does a generator work

Answer 14

• Turbine spins from an energy source (like wind, water, steam).
  -Coil of wire is attached to the turbine and spins inside a magnet.
• The magnetic field causes electrons in the wire to move.
  -Moving electrons = electric current (electricity!)

Question 15

External energy: Water

Answer 15

-Hydroelectric dams and tidal turbines spin turbines
-renewable
- Low emissions
- bad for marine life

Question 16

External energy: Fossil Fuels

Answer 16

• Burn coal/oil/gas to produce steam
  -Cheap, non-renewable

Question 17

External energy: Nuclear

Answer 17

• Heat from radioactive decay makes steam
  -Low carbon emissions but risk of radioactive waste

Question 18

External energy: Biomass

Answer 18

-Burn plant waste to make steam
- Widely available but pollutes air

Question 19

External energy: Geothermal

Answer 19

Uses Earth’s internal heat to make steam

Question 20

External energy: Wind

Answer 20

Wind rotates turbines

Question 21

External energy: Solar

Answer 21

Converts sunlight into electricity

Question 22

What is power?

Answer 22

Amount of energy converted per second.
Symbol: P
Unit: Watts (W)

Question 23

unit of electrical energy?

Answer 23

Joules (J)

Question 24

What is efficiency?

Answer 24

How much useful energy is produced compared to the energy input.

Question 25

What is electric current?

Answer 25

Flow of electrons past a point in a circuit Symbol: I Unit: Amperes (A)

Question 26

What is electric charge?

Answer 26

Quantity of electrons Symbol: Q Unit: Coulombs (C)

Question 27

What is potential difference (voltage)?

Answer 27

Force pushing electrons through the circuit Symbol: V Unit: Volts (V)

Question 28

What is resistance

Answer 28

Ability to oppose the flow of electrons Symbol: R Unit: Ohms (Ω)

Question 29

factors that affect resistance

Answer 29

Material: Better conductors = less resistance Cross-sectional area: Thicker wires = less resistance Length: Longer wires = more resistance Temperature: Higher temp = more resistance

Question 30

What is a fuse

Answer 30

Safety device that breaks the circuit if current is too high

Question 31

What is an ammeter

Answer 31

Measures current Must be connected in series with circuit

Question 32

In which direction do electrons flow?

Answer 32

Electrons flow from the negative terminal to the positive terminal

Question 33

Define electric current

Answer 33

Electric current (I) is the rate of electron flow past a specific point in the circuit

Question 34

What is an electric charge

Answer 34

quantity of electrons - measured in Coulombs

Question 35

need for fuses?

Answer 35

If there is too much current through the fuse, it is triggered (flips) and acting like a switch and interrupts the circuit so that no current flows through

Question 36

What is voltage?

Answer 36

Voltage is the force pushing the electricity through the wires

Question 37

How do you use a voltmeter

Answer 37

-Voltmeters are connected on either side of a load in a circuit -Voltmeters must be connected in parallel with the load or energy source -Measures the force of electrons moving in the circuit