A student set up the electrical circuit shown in Figure 9. Figure 9 The ammeter displays a reading of 0.10 A. Calculate the potential difference across the 45 Ω resistor. Potential difference = V Calculate the resistance of the resistor labelled R. Resistance = Ω State what happens to the total resistance of the circuit and the current through the circuit when switch S is closed.

GCSE AQA Physics Series & Parallel Circuits: A student set up the electrical

A student set up the electrical circuit shown in Figure 9 - AQA - GCSE Physics - Question 7 - 2018 - Paper 1

Question 7

A student set up the electrical circuit shown in Figure 9. Figure 9 The ammeter displays a reading of 0.10 A. Calculate the potential difference across the 45 Ω r... show full transcript

Worked Solution & Example Answer:A student set up the electrical circuit shown in Figure 9 - AQA - GCSE Physics - Question 7 - 2018 - Paper 1

Step 1

The ammeter displays a reading of 0.10 A. Calculate the potential difference across the 45 Ω resistor.

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Answer

To find the potential difference (V) across the 45 Ω resistor, we use Ohm's Law, which is given by:

$V = I imes R$

Where:

I = current (0.10 A)
R = resistance (45 Ω)

Therefore:

$V = 0.10 imes 45 = 4.5 ext{ V}$

Step 2

Calculate the resistance of the resistor labelled R.

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Answer

First, we find the total resistance (R_total) of the series circuit, which includes the 45 Ω and 60 Ω resistors:

$R_{total} = R_{45} + R_{60} = 45 + 60 = 105 ext{ Ω}$

We can calculate the resistance of resistor R using the formula:

$R = \frac{V}{I} = \frac{12 ext{ V}}{0.10 ext{ A}} = 120 ext{ Ω}$

Then subtract the combined resistance of the other resistors:

$R = R_{total} - 105 = 120 - 105 = 15 ext{ Ω}$

Step 3

State what happens to the total resistance of the circuit and the current through the circuit when switch S is closed.

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Answer

When switch S is closed, the total resistance of the circuit decreases. This happens because closing the switch provides a pathway that bypasses one of the resistors, effectively reducing the overall resistance. As a result, according to Ohm's Law, since the voltage remains constant, the current through the circuit will increase.

A student set up the electrical circuit shown in Figure 9 - AQA - GCSE Physics - Question 7 - 2018 - Paper 1

Worked Solution & Example Answer:A student set up the electrical circuit shown in Figure 9 - AQA - GCSE Physics - Question 7 - 2018 - Paper 1

The ammeter displays a reading of 0.10 A. Calculate the potential difference across the 45 Ω resistor.

Calculate the resistance of the resistor labelled R.

State what happens to the total resistance of the circuit and the current through the circuit when switch S is closed.

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