Science Test electricity

Question 1

define current electricity

Answer 1

controlled flow of electrons

Question 2

What is the difference between static and current?

Answer 2

Static: electrons gather in one place and move randomly in all directions
Current: controlled flow of electrons

Question 3

What are the different parts of a circuit?

Answer 3

Load: part of electric circuit that converts electrical energy into other forms of usable energy
Energy source: where the electrical energy comes from
Switch: device that controls flow of electrons by breaking or completing the circuit
Electrical wires: pathway for electrons to travel

Question 4

What is a short circuit?

Answer 4

An accidental connection between two points in a circuit

Question 5

What are the hazards associated With short circuits?

Answer 5

Electrocution
Electrical shock
Fires

Question 6

What is an electric cell?

Answer 6

Portable device that converts chemical energy into electrical energy
Chemical reaction creates a positive and negative end

Question 7

What is the difference between a primary and secondary cell?

Answer 7

Primary cell: uses non-reversible chemical, so it cannot be recharged
Secondary cell: uses a reversible chemical reaction and can be recharged

Question 8

How does direct current differ from alternating current?

Answer 8

Direct current:
Electrons flow in one direction through a circuit
Produced by an electric cell (battery) to power electric device
Alternating current:
Electrons move back and forth, changing directions
Produced by generators
More efficient method of distributing electrical energy over long distances
Found in wall outlets and lights

Question 9

How does a generator work?

Answer 9

Converts kinetic energy into electrical energy
External energy source spins the turbine which turns the coil of wire
Since the coil is moving near a magnet, the magnetic force forces electrons to move through the wire
Components: turbine, wire coil, magnet

Question 10

water source of external energy:

Answer 10

Water:
Hydroelectricity
Tidal

Dam: Water stored high flows down to spin turbines.
Tidal: Tides move turbines to generate power

Disrupts aquatic ecosystems

Lowers greenhouse emissions

renewable

Question 11

steam source of external energy:

Answer 11

Radioactive
Fossil fuels

Nuclear: Radioactive heat makes steam to generate power.
Fossil fuels: Burning coal, oil, or gas makes steam to spin turbines.

Radioactive: Efficient, low carbon, but risky waste.
Fossil: Cheap, high emissions, warms planet.

nonrenewable

Question 12

steam source of external energy part 2:

Answer 12

Biomass
Geothermal

Biomass: Burning biomass makes steam to spin turbines.
Geothermal: Earth’s heat makes steam to generate power.

Biomass: Available fuel, causes air pollution.
Geothermal: Clean, but location-limited.

renewable

Question 13

wind source of external energy

Answer 13

Wind rotates turbine

Low operating cost Inconsistent source of energy (not always windy)

Renewable

Question 14

solar source of external energy

Answer 14

Light from sun is converted to electric energy using photovoltaic cell

Light from sun is converted to electric energy using photovoltaic cell

Renewable

Question 15

What is the unit for electricity?

Answer 15

energy =joules

Question 16

Triangle for JWT stands for

Answer 16

energy, power, time (in seconds)

Question 17

What is efficiency?

Answer 17

Efficiency is a measure of how much useful energy gets produced by a device compared to the amount of energy supplied to it

Question 18

Which end of the battery is positive and negative?

Answer 18

The shorter end is negative
Longer end is positive

Question 19

which way do electrons flow

Answer 19

Electrons flow from the negative terminal to the positive terminal
As they move they lose potential energy

Question 20

Define electric current

Answer 20

For any device to operate, it requires a steady flow of electrons
Electric current (I) is the rate of electron flow past a specific point in the circuit
Current is measured in amperes (A)

Question 21

Outline the risks associated with electric current.

Answer 21

electricution

Question 22

Explain the need for fuses and how they work

Answer 22

Very large currents can damage electrical devices
Fuses are connected in series with circuits leading to the electrical devices
If there is too much current through the fuse, it is triggered (flips) and acting like a switch
Interrupts the circuit so that no current flows through

Question 23

What is an ammeter

Answer 23

An ammeter is a device used to measure current flowing through different loads of the circuit

An Ammeter must be hooked up in series with other components in a circuit so that electrons flow through it

Question 24

What is an electric charge

Answer 24

Electric charge is the quantity of electrons - measured in Coulombs ©

Question 25

What does the triangke for QIT stand for

Answer 25

charge, current time (in seconds)

Question 26

unit for QIT triangle

Answer 26

Q= coulombs I=ampers T= seconds

Question 27

What is voltage?

Answer 27

Energy is the ability to do work or move things Potential energy is stored energy The potential energy of electrons decreases as you move through the circuit Voltage is the force pushing the electricity through the wires

Question 28

How do you use a voltmeter

Answer 28

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

Question 29

what does VEQ triangle stand for

Answer 29

V= voltage, E=energy, Q=charge

Question 30

units for VEQ triangle

Answer 30

V= volts, E= coloumb, Q= joules

Question 31

Define Resistance.

Answer 31

Resistance is the ability to slow down or oppose the flow of electrons

Question 32

Describe various factors that affect the resistance of a wire

Answer 32

Insulators are considered to have very high resistance so electrons do not flow easily Conductors have very low resistance so electrons can flow easily The more energy it take to get the electrons to flow the greater the resistance

Question 33

Material

Answer 33

The ability of the material to conduct electricity is determined by how freely electrons can move within it Ex. copper is an excellent conductor

Question 34

Cross sectional area

Answer 34

The larger diameter = less resistance Thicker wires have less resistance than thinner ones because electrons have more room to flow through them

Question 35

Length of wire

Answer 35

As you increase the length of the wire, resistance increases Electrons have to travel through more material

Question 36

Temperature

Answer 36

Higher temperatures increase resistance Heat causes atoms to vibrate faster, making it hard for electrons to move through More vibrations means more collisions, creating more resistance

Question 37

Apply Ohm’s Law to solve for unknown variables

Answer 37

Ohm’s law states that the current through a conductor between two points corresponds to the voltage across two points Symbol: R Unit: Ohm (Ω), greek letter omega Use the V=I x R triangle

Question 38

Ohms law triangle

Answer 38

VIR V=volts I= current (im amps) R= resistance (in ohms)

Question 39

What is power?

Answer 39

Power is the measurement of the amount of energy converted per unit of time Electrical energy cannot be destroyed only converted or changed into other forms (heat, sound, motion, potential energy) Symbol: P or W Unit: Watts (W)

Question 40

triangle for power

Answer 40

PIV P= power (in watts) I= current (in amps) V= voltage (in volts)