2 Using Energy

Question 1

What is a primary source of energy?
-A naturally occurring source
Give one example of a secondary source of energy:
-Electricity
What major pollutant is produced when burning a fossil fuel?
-Carbon dioxide
How many joules of energy are transferred in 10 seconds by a 60w lamp?
-600J
A low energy electric lamp is marked ‘20W’ and gives out 10W of light. How efficient is the lamp?
-50%

Answer 1

What is the energy measured in?
-Joules
Equation for power:
-power(watts)=potential difference(volts) x current(ampere)
A 2kW electric heater is left running for 5 hours. How many kWh of energy are transferred?
-10kWh
A 3kWh heater is left on for 2 hours. How much does this cost at 10p per kWh?
-60p