10 questions๐ฌ๐งEnglish
๐ Electricity in the Home โ GCSE
Physics ยท GCSE โ AC and DC, three-pin plugs, fuses, power calculations and the National Grid
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Questions
What is the main difference between alternating current (AC) and direct current (DC)?
AC repeatedly reverses its direction
AC has no potential difference
AC always flows in one direction
AC only comes from batteries
20s
What are the voltage and frequency of the UK mains electricity supply?
230 V and 60 Hz
120 V and 50 Hz
110 V and 60 Hz
230 V and 50 Hz
20s
In a UK three-pin plug, what colour is the insulation on the live wire?
Brown
Black
Blue
Green and yellow stripes
20s
What is the main job of the earth wire in an appliance with a metal case?
It raises the voltage of the supply
It completes the circuit in normal use
It carries the current to the appliance
It stops the case staying live if a fault occurs
30s
A kettle connected to the 230 V mains draws a current of 10 A. What is its power?
240 W
23 W
230 W
2300 W
30s
A 920 W toaster runs on 230 V mains. Which standard fuse should be fitted in its plug?
13 A
1 A
3 A
5 A
30s
A 2000 W hairdryer is used for 5 minutes. How much energy does it transfer?
10 000 J
60 000 J
6000 J
600 000 J
30s
A current of 3 A flows through a heating element with a resistance of 20 ฮฉ. What is the power transferred?
1200 W
180 W
60 W
360 W
30s
Why do step-up transformers increase the voltage before electricity is sent along National Grid cables?
It increases the resistance of the cables
It changes the supply from AC into DC
It lowers the current, so less energy is lost as heat
It raises the current, so more power is delivered
30s
A 100% efficient transformer has 25 000 V and 40 A in the primary coil. Its secondary voltage is 400 000 V. What is the secondary current?
16 A
0.25 A
640 A
2.5 A
60s