Figure 1 shows how the National Grid connects a power station to consumers. use the physics equations sheet to answer questions u1.2 and u1.3. Which equation links current (I), power (P) and resistance (R)? Tick (✔) one box. A transmission cable has a power loss of 1.60 × 10^9 W. The current in the cable is 2000 A. Calculate the resistance of the cable. Resistance = Write down the equation which links efficiency, total energy input and useful energy output. The total energy input to the National Grid from one power station is 34.2 GJ. The National Grid has an efficiency of 0.992. Calculate the useful energy output from this power station to consumers in GJ.

GCSE AQA Physics Current, Potential Difference & Resistance: Figure 1 shows how the National

Figure 1 shows how the National Grid connects a power station to consumers - AQA - GCSE Physics - Question 1 - 2023 - Paper 1

Question 1

Figure 1 shows how the National Grid connects a power station to consumers. use the physics equations sheet to answer questions u1.2 and u1.3. Which equation links... show full transcript

Worked Solution & Example Answer:Figure 1 shows how the National Grid connects a power station to consumers - AQA - GCSE Physics - Question 1 - 2023 - Paper 1

Step 1

Which equation links current (I), power (P) and resistance (R)?

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Answer

The correct equation that links current, power, and resistance is given by the formula $P = I^2 R$ . This indicates that power (P) is equal to the square of the current (I) multiplied by the resistance (R).

Step 2

Calculate the resistance of the cable.

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Answer

To calculate the resistance of the cable, we use the formula for power loss:

$P = I^2 R$

Given the power loss of $1.60 imes 10^9 ext{ W}$ and the current of $2000 ext{ A}$ :

$1.60 imes 10^9 = (2000)^2 imes R$

Solving for R:

$R = \frac{1.60 imes 10^9}{2000^2}$

$R = \frac{1.60 imes 10^9}{4000000} = 400 \text{ Ω}$

Thus, the resistance of the cable is 400 Ω.

Step 3

Write down the equation which links efficiency, total energy input and useful energy output.

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Answer

The equation that links efficiency, total energy input, and useful energy output is:

$\text{efficiency} = \frac{\text{useful energy output}}{\text{total energy input}}$

Step 4

Calculate the useful energy output from this power station to consumers in GJ.

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Answer

To find the useful energy output, we can apply the efficiency equation:

Given the total energy input of 34.2 GJ and efficiency of 0.992:

$\text{useful energy output} = 0.992 \times 34.2$

Calculating this gives:

$\text{useful energy output} = 33.9 \text{ GJ}$

Thus, the useful energy output from the power station to consumers is approximately 33.9 GJ.

Figure 1 shows how the National Grid connects a power station to consumers - AQA - GCSE Physics - Question 1 - 2023 - Paper 1

Worked Solution & Example Answer:Figure 1 shows how the National Grid connects a power station to consumers - AQA - GCSE Physics - Question 1 - 2023 - Paper 1

Which equation links current (I), power (P) and resistance (R)?

Calculate the resistance of the cable.

Write down the equation which links efficiency, total energy input and useful energy output.

Calculate the useful energy output from this power station to consumers in GJ.

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