A capacitor consists of two parallel square plates of side / separated by distance d - AQA - A-Level Physics - Question 20 - 2017 - Paper 2
Question 20
A capacitor consists of two parallel square plates of side / separated by distance d. The capacitance of the arrangement is C.
What is the capacitance of a capacito... show full transcript
Worked Solution & Example Answer:A capacitor consists of two parallel square plates of side / separated by distance d - AQA - A-Level Physics - Question 20 - 2017 - Paper 2
Step 1
What is the capacitance of a capacitor with square plates of side 2?
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Answer
The capacitance of a capacitor is given by the formula:
C = rac{ ext{ε} imes A}{d}
where
a is the area and d is the distance between the plates. For square plates, the area A will change with the side length.
Step 2
Determine the new area
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Answer
If the side length of the plates is increased from l to 2l, the new area A' is calculated as:
A′=(2l)2=4l2=4A
where A is the original area.
Step 3
Calculate capacitance with updated area and distance
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Answer
Now using the new area with the reduced separation distance d/2, we substitute into the capacitance formula:
C' = rac{ ext{ε} imes A'}{d/2} = rac{ ext{ε} imes 4A}{d/2}. This simplifies to:
