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AQA GCSE · Question 04.4 · Electricity
When an earthed conductor is moved towards the negatively charged metal dome, there is a spark between the dome and the earthed conductor. The spark transfers 0.60 J of energy, and 2.0 μC of charge is transferred from the dome to the earthed conductor.
Calculate the potential difference between the metal dome and the earthed conductor. Use the Physics Equations Sheet.
When an earthed conductor is moved towards the negatively charged metal dome, there is a spark between the dome and the earthed conductor. The spark transfers 0.60 J of energy, and 2.0 μC of charge is transferred from the dome to the earthed conductor.
Calculate the potential difference between the metal dome and the earthed conductor. Use the Physics Equations Sheet.
How to approach this question
1. Identify the given values: Energy transferred (E) and charge flow (Q).
2. Convert the charge from microcoulombs (μC) to coulombs (C). Remember that "micro" (μ) means 10⁻⁶.
3. Find the equation on your sheet that links E, Q, and potential difference (V). It is E = Q V.
4. Rearrange the equation to make V the subject.
5. Substitute the values for E and Q (in coulombs) into the rearranged equation and calculate V.
Full Answer
1. Convert charge from μC to C:
Q = 2.0 μC = 2.0 × 10⁻⁶ C
2. Recall the equation linking energy (E), charge (Q), and potential difference (V):
E = Q V
3. Rearrange the equation to solve for V:
V = E / Q
4. Substitute the values and calculate:
V = 0.60 J / (2.0 × 10⁻⁶ C)
V = 300,000 V or 3.0 × 10⁵ V
The potential difference (V) is defined as the energy transferred (E) per unit charge (Q).
The equation is V = E / Q.
Step 1: Identify the given values and convert to SI units.
Energy transferred, E = 0.60 J.
Charge flow, Q = 2.0 μC. The prefix "μ" (micro) means 10⁻⁶.
So, Q = 2.0 × 10⁻⁶ C.
Step 2: Substitute the values into the equation.
V = E / Q
V = 0.60 J / (2.0 × 10⁻⁶ C)
Step 3: Calculate the result.
V = 300,000 V.
This can also be written in standard form as 3.0 × 10⁵ V or as 300 kV.
Common mistakes
✗ Forgetting to convert microcoulombs to coulombs.
✗ Using the equation incorrectly, e.g., multiplying E and Q.
✗ Errors in calculation or using standard form.
Practice the full AQA GCSE Physics Higher Tier Paper 1
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