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Difference between revisions of "Kilowatt-hour"
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: [[Energy]] ([[kilowatt-hour]]s) = [[Power]] ([[kilowatt]]s) x [[time]] ([[hour]]s)
 
: [[Energy]] ([[kilowatt-hour]]s) = [[Power]] ([[kilowatt]]s) x [[time]] ([[hour]]s)
 
: A '''kilowatt-hour''' is 3,600,000 [[Joule]]s.
 
: A '''kilowatt-hour''' is 3,600,000 [[Joule]]s.
 +
 +
===Energy Usage of Appliances===
 +
: The amount of [[energy]] an '''appliance''' uses depends on the power rating and how long the '''appliance''' is used for.
 +
: [[Energy]] usage for '''appliances''' is measured in [[kilowatt-hour]]s. This means all [[power]] ratings need to be in [[kilowatt]]s and time should be in [[hour]]s.
 +
: [[Energy]] can be calculated with the equation: [[Energy]] = [[Power]] x [[time]]
 +
 +
{| class="wikitable"
 +
|+ The Power ratings of some electrical appliances.
 +
|-
 +
| style="height:20px; width:250px; text-align:center;" |'''Filament Bulb'''
 +
A 60[[Watt]] filament bulb may be used for 8 hours a day. Calculate the [[energy]] in kilowatt-hours.
 +
| style="height:20px; width:250px; text-align:center;" |'''Energy Saving Bulb'''
 +
A 25[[Watt]] energy saving bulb may be used for 8 hours a day. Calculate the [[energy]] in kilowatt-hours.
 +
| style="height:20px; width:250px; text-align:center;" |'''Kettle'''
 +
A 2000[[Watt]] kettle may be used for 30 minutes a day. Calculate the [[energy]] in kilowatt-hours.
 +
|-
 +
| style="height:20px; width:250px; text-align:left;" |
 +
: Power = 60W = 0.060kW
 +
: Time = 8 hours
 +
: Energy = Power x time
 +
: Energy = 0.060 x 8
 +
: Energy = 0.48kilowatt-hours
 +
 +
| style="height:20px; width:250px; text-align:left;" |
 +
: Power = 25W = 0.025kW
 +
: Time = 8 hours
 +
: Energy = Power x time
 +
: Energy = 0.025 x 8
 +
: Energy = 0.20kilowatt-hours
 +
 +
| style="height:20px; width:250px; text-align:left;" |
 +
: Power = 2000W = 2.0kW
 +
: Time = 30 minutes = 0.5hours
 +
: Energy = Power x time
 +
: Energy = 2.0 x 0.5
 +
: Energy = 1.0kilowatt-hours
 +
|-
 +
| style="height:20px; width:250px; text-align:center;" |'''Television'''
 +
A 250[[Watt]] television is left on for 3 hours each day. Calculate the [[energy]] in kilowatt-hours.
 +
| style="height:20px; width:250px; text-align:center;" |'''Refrigerator'''
 +
A 200[[Watt]] refrigerator is on for 24 hours each day. Calculate the [[energy]] in kilowatt-hours.
 +
| style="height:20px; width:250px; text-align:center;" |'''Oven'''
 +
A 2500[[Watt]] oven is used for 45 minutes each day. Calculate the [[energy]] in kilowatt-hours.
 +
|-
 +
| style="height:20px; width:250px; text-align:left;" |
 +
: Power = 250W = 0.25kW
 +
: Time = 3 hours
 +
: Energy = Power x time
 +
: Energy = 0.25 x 3
 +
: Energy = 0.75kilowatt-hours
 +
 +
| style="height:20px; width:250px; text-align:left;" |
 +
: Power = 200W = 0.20kW
 +
: Time = 24 hours
 +
: Energy = Power x time
 +
: Energy = 0.20 x 24
 +
: Energy = 4.8kilowatt-hours
 +
 +
| style="height:20px; width:250px; text-align:left;" |
 +
: Power = 2500W = 2.5kW
 +
: Time = 45 minutes = 0.75 hours
 +
: Energy = Power x time
 +
: Energy = 2.5 x 0.75
 +
: Energy = 1.875kilowatt-hours
 +
|}

Revision as of 07:50, 11 June 2019

Key Stage 3

Meaning

A kilowatt-hour is a unit of energy used for electrical appliances and in electrical bills.

About kilowatt-hours

The kilowatt-hour is used by electricity suppliers instead of Joules.
A kilowatt-hour is calculated by multiplying the power rating of an appliance in kilowatts by the time the appliance is used for in hours.
Energy (kilowatt-hours) = Power (kilowatts) x time (hours)
A kilowatt-hour is 3,600,000 Joules.

Energy Usage of Appliances

The amount of energy an appliance uses depends on the power rating and how long the appliance is used for.
Energy usage for appliances is measured in kilowatt-hours. This means all power ratings need to be in kilowatts and time should be in hours.
Energy can be calculated with the equation: Energy = Power x time
The Power ratings of some electrical appliances.
Filament Bulb

A 60Watt filament bulb may be used for 8 hours a day. Calculate the energy in kilowatt-hours.

Energy Saving Bulb

A 25Watt energy saving bulb may be used for 8 hours a day. Calculate the energy in kilowatt-hours.

Kettle

A 2000Watt kettle may be used for 30 minutes a day. Calculate the energy in kilowatt-hours.

Power = 60W = 0.060kW
Time = 8 hours
Energy = Power x time
Energy = 0.060 x 8
Energy = 0.48kilowatt-hours
Power = 25W = 0.025kW
Time = 8 hours
Energy = Power x time
Energy = 0.025 x 8
Energy = 0.20kilowatt-hours
Power = 2000W = 2.0kW
Time = 30 minutes = 0.5hours
Energy = Power x time
Energy = 2.0 x 0.5
Energy = 1.0kilowatt-hours
Television

A 250Watt television is left on for 3 hours each day. Calculate the energy in kilowatt-hours.

Refrigerator

A 200Watt refrigerator is on for 24 hours each day. Calculate the energy in kilowatt-hours.

Oven

A 2500Watt oven is used for 45 minutes each day. Calculate the energy in kilowatt-hours.

Power = 250W = 0.25kW
Time = 3 hours
Energy = Power x time
Energy = 0.25 x 3
Energy = 0.75kilowatt-hours
Power = 200W = 0.20kW
Time = 24 hours
Energy = Power x time
Energy = 0.20 x 24
Energy = 4.8kilowatt-hours
Power = 2500W = 2.5kW
Time = 45 minutes = 0.75 hours
Energy = Power x time
Energy = 2.5 x 0.75
Energy = 1.875kilowatt-hours
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