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A parallel-plate capacitor is fully charged and then disconnected from the power supply - AQA - A-Level Physics - Question 18 - 2017 - Paper 2
Question 18
A parallel-plate capacitor is fully charged and then disconnected from the power supply. A dielectric is then inserted between the plates. Which row correctly ident... show full transcript
Worked Solution & Example Answer:A parallel-plate capacitor is fully charged and then disconnected from the power supply - AQA - A-Level Physics - Question 18 - 2017 - Paper 2
Step 1
Charge on the plates
Answer
When a fully charged capacitor is disconnected from the power supply, the charge on the plates remains constant. The insertion of a dielectric does not change the total charge stored on the capacitor because it is not connected to a voltage source. Therefore, the charge stays the same.
Step 2
Electric field strength between the plates
Answer
The electric field strength between the plates of a capacitor with a dielectric inserted decreases. This is due to the polarization of the dielectric material, which reduces the effective electric field within the capacitor. Thus, the electric field strength decreases when the dielectric is inserted.