A student investigates resistors connected in parallel using a number of resistors - Edexcel - GCSE Physics Combined Science - Question 5 - 2020 - Paper 1
Question 5
A student investigates resistors connected in parallel using a number of resistors.
Each resistor has the same resistance.
Figure 10 shows a circuit diagram with on... show full transcript
Worked Solution & Example Answer:A student investigates resistors connected in parallel using a number of resistors - Edexcel - GCSE Physics Combined Science - Question 5 - 2020 - Paper 1
Step 1
Add to Figure 10:
a) a voltmeter to find the potential difference across resistor R
b) another resistor in parallel with resistor R.
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Answer
To add the voltmeter, position it in parallel with resistor R. To add another resistor, connect it in parallel to resistor R in the diagram.
Step 2
State the measurements that the student must take to find the overall resistance of the resistors in parallel.
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Answer
The student must measure the potential difference (voltage) across the resistors in parallel using a voltmeter and the current flowing through the circuit using an ammeter.
Step 3
State the resistance of a single resistor.
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Answer
The resistance of a single resistor is 1 Ω.
Step 4
Comment on the relationship between the overall resistance of the circuit and the number of resistors in parallel.
Use information from Figure 11 to support your answer.
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Answer
The overall resistance of the circuit decreases as the number of resistors in parallel increases. This relationship is non-linear, indicating that as more resistors are added, the resistance decreases at a decreasing rate. For example, from Figure 11, when increasing from 1 to 2 resistors, the overall resistance drops significantly, but the drop becomes less pronounced as more resistors are added.
Step 5
Calculate the potential difference across the 15 Ω resistor.
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Answer
Using Ohm's law, where V = I × R, the potential difference across the 15 Ω resistor can be calculated as:
V=0.20A×15Ω=3V.
Step 6
Calculate the total power dissipated when there is a current of 0.20A in the two resistors.
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Answer
To calculate the total power dissipated, use the formula:
P=I×R.
The total resistance R = 15 Ω + 20 Ω = 35 Ω, thus:
