2.3 Practical Electricity

Question 1

How are electrons arranged in a conductor?

Answer 1

The electrons are free to move throughout the structure.

Question 2

How are electrons arranged in insulators?

Answer 2

The electrons are tightly bound and cannot move.

Question 3

What is the electric current in an electrical circuit?

Answer 3

The flow of electrons around a circuit. (the greater the flow, the greater the current)

Question 4

Describe a series circuit.

Answer 4

When components are connected in line, it is said to be connected in series.

Question 5

What is the unit of current?

Answer 5

Amperes (A)

Question 6

What is the current at different points in a series circuit?

Answer 6

The same as the current from the battery.

A1= A2= A3

Question 7

Describe a parallel circuit.

Answer 7

When components are connected so that there is more than one path for the current, it is said to be connected in parallel.

Question 8

What is current like in a parallel circuit?

Answer 8

The sum of currents through each component in a parallel circuit, adds up to the current which flows from the supply
A= A1+ A2

Question 9

What is the voltage in an electrical circuit?

Answer 9

The electrical energy supplied by the battery to make the electrons move around the circuit.

Question 10

What is the unit of voltage?

Answer 10

Volts (V)

Question 11

What is voltage like in a series circuit?

Answer 11

The sum of voltages across each component in a series circuit adds up to the supply voltage
V= V1+ V2

Question 12

What is the voltage at different points in a parallel circuit?

Answer 12

The same as the supply voltage.

V1= V2= V3

Question 13

What is resistance in an electrical current?

Answer 13

The opposition to the flow of current in a circuit

Question 14

What is the unit of electrical resistance?

Answer 14

Ohms (Ω)

Question 15

What are some factors that affect resistance?

Answer 15

Type of material- the better the conductor, the lower the resistance
Length of material- the longer, the higher the resistance
Thickness of material- the thicker, the lower the resistance
Temperature of material- (usually) the higher, the higher the resistance

Question 16

What happens to the current in a circuit when resistance in the circuit changes?

Answer 16

If resistance increases, the current decreases.

Question 17

What is the equation to calculate the resistance? (Ohm’s Law)

Answer 17

Resistance= voltage/ current 
R= V/I

Question 18

What are some practical applications of a variable resistance?

Answer 18

Light dimmer controls
Volume and brightness controls
Speed controls on electric motors

Question 19

What is electric current?

Answer 19

The movement of a group of electrons around a circuit.

Question 20

What is the equation involving charge, current and time?

Answer 20

Current= charge/ time 
I= Q/t

Question 21

What is the difference between alternating and direct current?

Answer 21

A.C is produced from the mains supply. The electrons flow around in one direction then the direction changes and the electrons flow in the opposite direction.
D.C is prodcued from a battery. The electrons always flow in one direction around the circuit

Question 22

What is the effect of an electric field on a negative charge?

Answer 22

It would be accelerated towards the positive plate due to both replusion of the negative plate and the attraction to the positive plate.

Question 23

What is the potential difference between two parallel charged plates?

Answer 23

A measure of the energy given to the charges when they move between the plates.

Question 24

What is the equation involving resistance in series?

Answer 24

RT= R1+ R2+ R3

Question 25

What is the equation involving resistance in parallel?

Answer 25

1/RT= 1/R1+ 1/R2+ 1/R3

Question 26

What is the equation involving potential difference, current and resistance?

Answer 26

Voltage= current x resistance
V= I x R