a 2000 W electrical fire is used for 10 hours , what is the cost at 8p per kWh
energy = power * time
cost = number of kWh * cost per kWh
2 kW * 10 = 20 kWh
20*8 = 160p
if electrical energy costs 9p per unit , calculate the cost of leaving a 3 kW fire switched on for 12 hours
energy = power * time
cost = cost per kWh * number of kWh
3 * 12 = 36 kWh
36 * 9 = 324p
if electrical energy costs 9p per unit , calculate the cost of leaving a 120 W T.V. switeched on for 8 hours
energy = power * time
cost = cost per kWh * number of kWh
0.12 * 8 = 0.96 kWh
0.96 * 9 = 8.64p
an electric lamp is marked 100 W . find the cost of using it for 6 hours at 8p per unit
energy = power * time
cost = number of kWh * cost per kWh
0.1*6 = 0.6 kWh
0.6 * 8 = 4.8p
a 3 kW fire is switched on for 15 minutes . calculate the cost if electrical energy is 9p per unit
energy = power * time
cost = number of kWh * cost per kWh
3*15/60 = 0.75 kWh
0.75 * 9 = 6.75p
the diagram below shows an electricity/energy meter
a) how much electricity has been used
b) the electricity costs 9p per unit . whats is the cost of using this quantity of electricity
c) 2047 units are used in the next billing period . What is the new reading on the meter
cost = number of kWh * price per kWh
a) 61973-59321= 2652 kWh
b) 2652 * 9 = 23868p = £238.68
c) 61973 + 2047 = 64020
a 2 kW washing machine for 3 hours if the cost per kWh is 7p
energy = power * time
cost = cost per kWh * number of kWh
2*3 = 6 kWh
6*7 = 42p
a 1000 W heater for 2 hours if the cost per kWh is 5p
energy = power * time
cost = cost per kWh * number of kWh
1*2 = 2 kWh
2*5 = 10p
a 250 W food mixer for an hour if the cost per kWh is 9p
energy = power * time
cost = cost per kWh * number of kWh
0.25*1 = 0.25 kWh
0.25*9 = 2.25p
a 3 kWh tumble drier for 90 minutes if the cost per kWh is 4p
energy = power * time
cost = cost per kWh * number of kWh
3*90/60 = 4.5 kWh
4.5*4 = 18p
a 100 W lamp for 30 minutes if the cost per kWh ia 10p
energy = power * time
cost = cost per kWh * number of kWh
0.1*0.5 = 0.05 kWh
0.05 * 10 = 0.5p
a 1250 W cooker for 90 minutes if the cost per kWh is 6p