Some students investigate electric circuits - Edexcel - GCSE Physics - Question 3 - 2012 - Paper 1
Question 3
Some students investigate electric circuits.
They set up this circuit.
What can the students do to increase the brightness of the lamp?
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Worked Solution & Example Answer:Some students investigate electric circuits - Edexcel - GCSE Physics - Question 3 - 2012 - Paper 1
Step 1
What can the students do to increase the brightness of the lamp?
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Answer
To increase the brightness of the lamp, the students should decrease the resistance of the variable resistor. This allows more current to flow through the circuit, resulting in a brighter lamp.
Step 2
(b)(i) Complete the circuit below with an ammeter and a voltmeter correctly connected.
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Answer
In the circuit diagram, connect the ammeter in series with the lamp and connect the voltmeter in parallel to the lamp. This configuration allows the ammeter to measure the current flowing through the lamp and the voltmeter to measure the potential difference across it.
Step 3
(b)(ii) Calculate the potential difference (voltage) across the lamp.
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Answer
Using Ohm's law, we know that Voltage (V) = Current (I) × Resistance (R). Here, I = 0.5 A and R = 8 Ω. Thus,
V=0.5extAimes8extΩ=4extV
Therefore, the potential difference across the lamp is 4 V.
Step 4
(c) Explain why only some of the electrical energy is transferred to light energy in the lamp.
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Not all electrical energy is converted into light energy because some energy is lost as heat due to the resistance in the filament of the lamp. This energy loss means that only a portion of the electrical energy is efficiently converted into light.
Step 5
(d) Calculate the power being supplied to the lamp.
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The power (P) supplied to the lamp can be calculated using the formula:
P=VimesI
Here, V = 5 V and I = 0.4 A. Thus,
P=5extVimes0.4extA=2extW
Therefore, the power being supplied to the lamp is 2 W.
