A parallel-plate capacitor is made using a sheet of dielectric material between, and in contact with, two plates - AQA - A-Level Physics - Question 21 - 2020 - Paper 2
Question 21
A parallel-plate capacitor is made using a sheet of dielectric material between, and in contact with, two plates.
The properties of four sheets of dielectric materia... show full transcript
Worked Solution & Example Answer:A parallel-plate capacitor is made using a sheet of dielectric material between, and in contact with, two plates - AQA - A-Level Physics - Question 21 - 2020 - Paper 2
Step 1
Determine the capacitance formula
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Answer
The capacitance (C) of a parallel-plate capacitor with a dielectric material can be expressed as:
C = rac{ ext{Permittivity} imes A}{d}
where:
Permittivity = εr⋅ε0, with εr being the relative permittivity and ε0 being the permittivity of free space.
A is the area of the plates (assumed constant).
d is the thickness of the dielectric material.
Step 2
Calculate the capacitance for each sheet
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Answer
Using the above formula and noting that ε0 and A are constants, we focus on relative permittivity divided by thickness:
For sheet A: CA=0.402=5
For sheet B: CB=0.903≈3.33
For sheet C: CC=1.04=4
For sheet D: CD=1.66≈3.75
Step 3
Compare the results
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Answer
To maximize capacitance, we compare the calculated values:
A: 5
B: 3.33
C: 4
D: 3.75
Sheet A provides the highest capacitance.
Step 4
Final Answer
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Answer
The sheet that will produce the maximum capacitance is Sheet A.
