A-Level Physics Question Analysis Topic: Physics - Short Questions
Exam Questions:
1) Why do the electrostatic field lines not form closed loops?
2) Why is choke coil needed in the use of fluorescent tubes with ac mains?
Answer:
For A-Level Physics, you should know:
1) When a unit positive test charge is placed along a line, the path it takes is known as the electric line of force. If the electric field line is a closed loop, the positive test charge would return to the positive source charge, which is not possible because previously there was repulsion and it has since changed to attraction.
2) A choke coil is used in place of a resistance to control the current in a.c. circuits. The electrical energy will be lost as heat if a resistance is utilised to regulate the current. A choke coil reduces the current without squandering electrical energy as heat because of its inductive reactance.
Work hard for your A-Level Physics examination!
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