Heater A transfers 500 J in 1 s. Heater B transfers 300 J in 1 s. Explain which is more powerful.
Kettle A transfers 16 J in 2 s. Kettle B transfers 18 kJ in 2 s. Explain which is more powerful.
What unit do we measure power in?
A fan has a rating of 50 W. How many joules of energy does it transfer each second?
A heater transfers 70 J in 1 s. What is its power rating?
Person A lifts a weight so that is gains 120 J in 3 s.
a) Which store of energy is decreasing?
Person A lifts a weight so that is gains 120 J in 3 s.
a) Which store of energy is increasing?
A TV has a power of 65 W. How many joules of energy does it transfer each second?
A TV set has a power of 800 watts and is switched on for 30 seconds. Calculate the energy transferred.
A toaster has a power of 1800 watts and is switched on for 25 seconds. Calculate the energy transferred.
An electric fan has a power of 350 watts and is switched on for 120 seconds. Calculate the energy transferred.
A kettle has a power of 850 watts and is switched on for 45 seconds. Calculate the energy transferred.
A kettle has a power of 2 kW. It is left on for 30s. How much energy is transferred? Give your answer in J and kJ.
Convert the following from J to kJ:
a) 2000 J
b) 3400 J
c) 800 J
d) 12 300 J
What happens to the energy transferred if we increases the time a device is switched on for?
In domestic settings, electricity usage is often measured in kilowatt‐hours to determine the amount of energy consumed by various appliances and devices. Energy companies use this unit to calculate electricity bills based on the total amount of kilowatt‐hours consumed by a household over a given period, such as a month. By monitoring the number of kilowatt‐hours consumed by different devices, homeowners can better understand how much energy is being used and take steps to reduce their energy consumption. For example, they might switch to more energy‐efficient appliances or turn off devices that are not in use to save on their electricity bills.
What is the benefit of using kilowatt‐hours (kWh) as a measure of energy consumption in households
and businesses?
How does understanding the concept of kWh help individuals and businesses better manage their
energy consumption?
Why is it important for utility companies to measure and bill customers based on their kWh
consumption?