1
1 mark
1 markWhich statement describes the domestic electricity supply in the UK?
50 V a.c. at 230 Hz
50 V d.c. at 230 Hz
230 V a.c. at 50 Hz
230 V d.c. at 50 Hz
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Energy Resources & Power Transmission (OCR GCSE Physics A (Gateway)): Exam Questions
Exam code: J249
1 hour18 questions
21 mark
A sound wave travels in air and enters water.
What happens to the sound wave as it enters the water?
| Speed | Frequency | Wavelength |
A | decreases | decreases | decreases |
B | decreases | stays the same | decreases |
C | increases | increases | increases |
D | increases | stays the same | increases |
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31 mark
The graph shows how the power generated by the wind in the UK varied over one day.
Which row in the table is correct?
| Maximum power generated (MW) | Reliability of wind power |
A | 5200 | Reliable |
B | 5200 | Unreliable |
C | 11000 | Reliable |
D | 11000 | Unreliable |
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41 mark
Which graph shows an alternating current (a.c.)?
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51 mark
Which row in the table is correct for a step-down transformer?
| Current | Potential difference |
A | Decreases | Decreases |
B | Decreases | Increases |
C | Increases | Decreases |
D | Increases | Increases |
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61 mark
Which frequency is used for electricity supplied to homes in the UK?
50 Hz a.c.
50 Hz d.c.
230 Hz a.c.
230 Hz d.c.
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71 mark
Which row in the table correctly describes how the national grid transfers electrical energy efficiently?
| Voltage | Current | Reason |
A | High | High | To increase heating in wires. |
B | High | Low | To reduce heating in wires. |
C | Low | High | To reduce heating in wires. |
D | Low | Low | To reduce heating in wires. |
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81 mark
Why are high voltages used to transfer electrical power from power stations in the National Grid?
They allow low resistance wires to be used.
They produce a higher current.
They reduce energy losses.
Voltage can be changed using transformers.
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91 mark
The diagram shows a simplified version of the national grid.
The potential difference (p.d.) is different at each point in the national grid.
Which row in the table is correct?
| p.d. at position 1 (V) | p.d. at position 2 (V) | p.d. at position 3 (V) |
A | 230 | 5 000 | 11 000 |
B | 25 000 | 450 000 | 11 000 |
C | 450 000 | 150 | 230 |
D | 450 000 | 5 000 | 230 |
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101 mark
Which statement shows energy resources that are all renewable?
Bio-fuel, wind, hydro-electricity and tides.
Fossil fuels, bio-fuel, wind and hydro-electricity.
Fossil fuels, nuclear fuel, hydro-electricity and tides.
Nuclear fuel, bio-fuel, wind and tides.
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111 mark
The National Grid transfers energy efficiently using high voltages.
Why are high voltages more efficient?
High voltages produce a high current which heats wires less.
High voltages produce a high current which heats wires more.
High voltages produce a low current which heats wires less.
High voltages produce a low current which heats wires more.
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121 mark
Which row correctly describes the domestic electricity supply in the UK?
| a.c. or d.c. | Frequency (Hz) | Voltage (V) |
A | a.c. | 50 | 230 |
B | a.c. | 230 | 50 |
C | d.c. | 50 | 230 |
D | d.c. | 230 | 50 |
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131 mark
The table shows the current and potential difference (p.d.) for four different transformers.
Which row shows the correct data for a step-up transformer?
| Primary coil | Secondary coil | ||
| p.d. (V) | Current (A) | p.d. (V) | Current (A) |
A | 6 | 4 | 12 | 2 |
B | 12 | 2 | 3 | 8 |
C | 12 | 2 | 12 | 2 |
D | 12 | 2 | 24 | 1.5 |
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