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A short copper rod R is placed on a pair of thick horizontal parallel copper rails - AQA - A-Level Physics - Question 21 - 2021 - Paper 2
Question 21
A short copper rod R is placed on a pair of thick horizontal parallel copper rails. A horizontal magnetic field exists in the direction shown by the dashed arrows. T... show full transcript
Worked Solution & Example Answer:A short copper rod R is placed on a pair of thick horizontal parallel copper rails - AQA - A-Level Physics - Question 21 - 2021 - Paper 2
Step 1
When switch S is closed, R will tend to
Answer
In this scenario, a current will flow through the copper rod R when switch S is closed. By applying the right-hand rule for motors, we can determine the direction of the force acting on the rod R.
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Determine the direction of the current: The current flows from the positive terminal to the negative, in the same direction as the conventional flow.
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Identify the magnetic field direction: The diagram shows a horizontal magnetic field directed horizontally.
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Use the right-hand rule: With your thumb pointing in the direction of the current (which flows along the rails), and the fingers pointing in the direction of the magnetic field, your palm will face upward. This indicates that the force acting on the rod R will push it upwards.
Based on this analysis, the correct answer is: A lift upwards away from the rails.