A technician is testing a filament lamp from a car - Edexcel - GCSE Physics - Question 4 - 2017 - Paper 1
Question 4
A technician is testing a filament lamp from a car.
He connects the lamp to a test circuit with a 1.5 V d.c. power supply.
(i) Complete the sentence by putting a c... show full transcript
Worked Solution & Example Answer:A technician is testing a filament lamp from a car - Edexcel - GCSE Physics - Question 4 - 2017 - Paper 1
Step 1
Complete the sentence by putting a cross (X) in the box next to your answer.
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Answer
The correct answer is: A. 1.5 joules per coulomb. This means that the power supply transfers energy as electric charge.
Step 2
Add an appropriate meter symbol to the circuit to show how the meter should be connected.
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Answer
The appropriate meter symbol to add is the ammeter symbol (A). It should be connected in series with the circuit to measure the current.
Step 3
Calculate the resistance of the filament in the lamp.
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Answer
Using Ohm's Law, the resistance (R) can be calculated using the formula:
R=IV
Given that voltage (V) = 1.5 V and current (I) = 0.18 A:
R=0.18A1.5V=8.33Ω
Thus, the resistance of the filament in the lamp is 8.33 Ohms.
Step 4
Calculate the power of the lamp.
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Answer
Power (P) can be calculated using the formula:
P=V×I
Here, voltage (V) = 12 V and current (I) = 0.8 A (800 mA).
Therefore:
P=12V×0.8A=9.6W
The power of the lamp when connected to the 12 V battery is 9.6 W.
Step 5
Explain why the current is not 400 mA.
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Answer
The current is not 400 mA because:
The resistance in the circuit has changed when it was connected to the 6 V battery, which results in a different current value.
The temperature of the filament may be lower with less voltage, causing it to be less bright and result in fewer collisions in the lattice, thus affecting the current.
Current is not directly proportional to voltage; it's influenced by the total resistance in the circuit.
