i)

Importance of a fuse in an electrical appliance

1. To protect electrical equipment from excessive current
2. It is used as safety measures to prevent any hazards to humans

ii)

Household appliances that have fuse

1. Lamps
2. Televisions
3. Wall socket
4. Computers
5. Kettle
6. Dishwasher
7. Fridges/freezers
8. Electric fan
9. Electric iron/iron
10. Microwave

i)

Potential difference also known as voltage, is the external work needed to bring a charge from one location to another location in an electric field.

OR

Is the work done in moving a unit of positive electric charge from one point to another.

ii)

Potential Difference (V) = Current x Resistance

V = IR
Where V = potential difference, I = current and R = resistance

Potential difference = 250 V
Resistance = 100 Ω

250 = I x 100

Divide both sides by 100 to solve for I.

I = $\frac{250}{100}$ = 2.5 A

The current flowing through the resistor is 2.5 A

(i)

L → Live
N → Neutral
E → Earth

(ii)

Function of the fuse box in household electrical wiring

1. It contains fuses/thin wires which melt and cut off current when the current passing through is too large

2. It protects the appliances/electrical circuit

(i)

Differences between electrical insulators and electrical conductors

(ii)

Effects of illegal electrical connections in the home

1. Overload of power supply
2. Drop in voltage of electricity
3. Leads to frequent power cuts
4. Leads to electrocution/electric shock
5. May cause fire outbreak
6. May damage electrical appliances
7. Leads to loss of revenue to government

(i)

A fuse is a short piece of wire with a low melting point which serves as a protective/safety device in an electric/electrical circuit.

(ii)

Why a fuse is used in an electrical circuit

It protects appliances when current becomes too high.

i)

Electrical insulator is a material that does not allow electricity to flow through it easily.

ii)

Examples of insulators

1. Wood
2. Plastic materials
3. Rubber
4. Paper
5. Glass
6. Nylon
7. Mica
8. Porcelain
9. Amber
10. Wax
11. Ceramic materials
12. Air

iii)

Characteristics of an insulator

1. There are no free electrons
2. Electrons are tightly bound to the nuclei
3. It has low charge density
4. It has low electrical conductivity

(i)

(ii)

(i)

$\frac{1}{{\mathrm{R}}_{\mathrm{T}}}$ = $\frac{1}{{\mathrm{R}}_1}$ + $\frac{1}{{\mathrm{R}}_2}$

$\frac{1}{{\mathrm{R}}_{\mathrm{T}}}$ = $\frac{1}{4}$ + $\frac{1}{5}$

$\frac{1}{{\mathrm{R}}_{\mathrm{T}}}$ = $\frac{\mathrm{5\; x\; 1\; +\; 4\; x\; 1}}{20}$

$\frac{1}{{\mathrm{R}}_{\mathrm{T}}}$ = $\frac{\mathrm{5\; +\; 4}}{20}$

$\frac{1}{{\mathrm{R}}_{\mathrm{T}}}$ = $\frac{9}{20}$

Cross multiply.

R_T x 9 = 1 x 20

Divide both sides by 9

R_T = $\frac{20}{9}$ Ω or 2$\frac{2}{9}$ Ω or 2.2 Ω

Note: mark is deducted for answer without unit (Ω)

(ii)

Voltage (V) = Current (I) x Resistance (R)

Voltage (V) = 6V

Resistance (R) = $\frac{20}{9}$ Ω

6 = I x $\frac{20}{9}$

Multiply both sides by the denominator 9

6 x 9 = 20 x I

Divide both sides by 20

I = $\frac{\mathrm{6\; x\; 9}}{20}$ = $\frac{27}{10}$ = 2.7 A

Note: Mark is deducted for answer without or incorrect unit.