# Physics question

Thread starter 4 years ago
#1
The national grid supplied a house with 18,000,000 j of energy in 1 hour. What was the average current supplied to the house during that hour? ( 5 marks) thanks
0
4 years ago
#2
(Original post by BOb148)
The national grid supplied a house with 18,000,000 j of energy in 1 hour. What was the average current supplied to the house during that hour? ( 5 marks) thanks
Q = E÷V
Charge flow = Energy ÷ Potential difference
Q=18,000,000 ÷ 230V
Q=78260.86956521738
I = Q÷t
Current = Charge ÷ time
Current = 78260.86956521739 ÷ 3600s
Current = 21.73913043478260 Amps
This sounds right because they use a low amp since to transfer a lot of energy you either use a high amp or voltage. Since a high amp dissipates a lot of thermal energy they use a low amp and high voltage. This was in the P1-4 test for combined science .
0
4 years ago
#3
Realised it's a gcse question.

Alternatively OP, You can say that Power = Energy transferred ÷ Time (In seconds)

then since you know Power = Voltage x Current
just divide the Power by 230V to get the value of Current.
1
4 years ago
#4
(Original post by Bulletzone)
Realised it's a gcse question.

Alternatively OP, You can say that Power = Energy transferred ÷ Time (In seconds)

then since you know Power = Voltage x Current
just divide the Power by 230V to get the value of Current.
Where did you get the 230V from?
0
4 years ago
#5
(Original post by whyrevision)
Where did you get the 230V from?
230 Volts is the standard UK potential difference of an Electrical A.C socket.
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