Electricity

Question 1

Define cell

Answer 1

Power generating component which converts stored chemical energy into electrical energy

Question 2

Define battery

Answer 2

2+ electrical cells joined to generate power and convert chemical energy into electrical energy

Question 3

Define resistor

Answer 3

Component that has electrical resistance and that is used in a electric circuit for protection, operation or current control

Question 4

Define switch

Answer 4

Electrical component that can disconnect or connect the conducting path in an electrical circuit, interrupting the electric current or diverting it from one conductor to another.

Question 5

Define lamp

Answer 5

Component that converts electrical energy into light and heat energy

Question 6

Define buzzer

Answer 6

An audio-signaling component

Question 7

Define motor

Answer 7

An electro-mechanical component which converts electrical energy into mechanical energy

Question 8

Define generator

Answer 8

A device that converts mechanical energy into electrical energy for use in an external circuit

Question 9

Define solar cell

Answer 9

Also known as a photovoltaic cell, it is a component that converts light energy directly into electricity

Question 10

Define transistor

Answer 10

Component used to control the flow of current and has the ability to amplify a current

Question 11

Define LED

Answer 11

Light Emitting Diode, a component which emits light when current passes through it. Also only allows current to flow in one direction

Question 12

Define LDR

Answer 12

Light-Dependent Resistor, controls the flow of current and has the ability to act as a switch. It’s functionality is dependent on the amount of light that hits the surface.

Question 13

Define thermistor

Answer 13

Type of resistor whose resistance changes with temperature

Question 14

Define capacitor

Answer 14

Component that stores energy for a short period of time and then releases it

Question 15

Define parallel circuit

Answer 15

More than one pathway to flow.

Question 16

Define series circuit

Answer 16

Only one pathway to flow. One component after another.

Question 17

Give advantages and disadvantages of a series circuit.

Answer 17

ADVANTAGES:
Easier to switch on/off - all appliances connected together
Safer - less current flows through circuit
Used when 100s/1000s of bulbs are to be used together, so that the same current passes through all, and can be switched on/off together

DISADVANTAGES:
Electrical appliance stop working = all stop working
All electrical appliances have only 1 switch = cannot be turned on/off separately
All appliances do not get the same voltage - voltage divided in series combination
Equivalent resistance increases too much = amount of current flowing becomes very small

Question 18

Give advantages and disadvantages of a parallel circuit.

Answer 18

ADVANTAGES:
Even if one appliance stops working, all others work fine
Individual appliances can be turned on/off separately
Each electrical appliance gets the same voltage as the power supply line.
Resistance of circuit decreases = appliances can draw more current to operate

DISADVANTAGES:
Method becomes cumbersome to use if thousands of bulbs/appliances are to be switched on/off
Less safe - more current can pass through circuit

Question 19

Describe the difference for cells when they are in series or in parallel.

Answer 19

IN SERIES:
Connected when the + terminal is connected to the - terminal of another cell

IN PARALLEL:
Connected when the + terminal of one cell is connected to the + terminal of another cell. And the - terminals are also connected

Question 20

Describe the difference for the potential difference when they are in series or in parallel.

Answer 20

IN SERIES:
Voltage added together = amount of energy will be greater throughout the circuit

IN PARALLEL:
Voltage remains the same = Amount of energy will be equally distributed throughout the circuit

Question 21

Describe the difference for bulbs when they are in series or in parallel.

Answer 21

IN SERIES:
Connected when the one terminal of a bulb holder is connected to the terminal of another bulb holder in a straight line.

IN PARALLEL:
Connected when the terminals of the bulb holders are placed across one another.

Question 22

Define logic gates

Answer 22

Electronic switch that is an assembly of switches connected in a specific way

Question 23

Define AND logic gate

Answer 23

Consists of 2 electronic switches connected in series
Both switches have to be closed for the circuit to be active
Switch A AND B has to be in the same state

Question 24

Define OR logic gate

Answer 24

Consists of 2 electronic switches connected in parallel
Either one of the switches must be closed for the circuit to be active
Switch A OR B has to be closed

Question 25

Define potential difference

Answer 25

Also known as voltage
Measured with a Voltmeter, connected in parallel
Measured in Volts (V)
Symbol: V

Question 26

Define current

Answer 26

Rate of flow of an electric charge past a (one) point in a circuit
Measured with an Ammeter, connected in series
Measured in Amperes (A)
Symbol: I
Current flows from + to negative = conventional flow

Question 27

Define resistance

Answer 27

Slows down the flow of charge in a circuit
Measured with an Ohmmeter
Measured in Ohms
Symbol: R

Question 28

Define Ohm’s law

Answer 28

As voltage increases, current increases, only if resistance is constant
OR
The current in a circuit is directly proportional to the voltage, and inversely proportional to the resistance, provided that the temperature is kept constant

Question 29

What is the formula for current?

Answer 29

I(current) = V(voltage) / R(resistance)

Question 30

What is the formula for voltage?

Answer 30

V(voltage) = I(current) x R(resistance)

Question 31

What is the formula for resistance?

Answer 31

R(resistance) = V(voltage) / I(current)