Assertion & Reason

Electricity and Magnetism Level 2

Read the following statements (assuming charge particles are light)

A. In the frame of reference where all considered charges are at rest, the force experienced by a moving test charge due to all considered charges is purely electrical

B. A stationary charge produces electric field only

Then which of the following is correct

A is correct, B is also correct & B is the correct explanation of A
A is correct, B is also correct but B is not the correct explanation of A
A is correct, B is incorrect
A is incorrect, B is correct

I will be posting series of assertion & Reason problems so that to clear basic concepts. :)

2 4 3 1

1 solution

Krishna Sharma
Jan 5, 2015

Statement A & B are correct and B is the correct explanation of A.

When

Charge is at rest :- it produces only Electric field
Charge is in uniform motion :- it produces Electric & Magnetic fields
Charge when accelerated :- it produces Electric field, Magnetic field & electromagnetic radiations.

Very true! But should we not consider gravitational field as well? I think charge cannot exist without mass. So both statements must be false.

Pranjal Jain - 6 years, 5 months ago

Ratio of gravitational force to electric force is very very less for example for 2 protons it is of the order $10^{-36}$ , even in the statement A it is mentioned force on moving test charge which means it is very light(considered massless), so it can be neglected.

Ps: I have clarified the problem.

Krishna Sharma - 6 years, 5 months ago

Yeah! I was a bit confused if you want it to be neglected or is it what you actually want to ask. But according to options, only one was correct.

Pranjal Jain - 6 years, 5 months ago

It should Be More Clearly Stated That all other Charges are ' Fixed ' . Because Feeling that may arise from this question is that Charges are at rest intially and Then due moving Charge They Can Move due to Elect. forces and Then it result in producing additional Mag. forces also .

Deepanshu Gupta - 6 years, 5 months ago

Charge is test charge its magnitude is very small so that it will not disturb the position of other charges.

Krishna Sharma - 6 years, 5 months ago

Absolutely ! And Yes It Should Be mentioned , But Ok, Now You Have Mentioned it !

Deepanshu Gupta - 6 years, 5 months ago

@Deepanshu Gupta – It was already mentioned.

Krishna Sharma - 6 years, 5 months ago

@Krishna Sharma – Okay , My bad , May be I doesn't Read it Carefully , :)

Deepanshu Gupta - 6 years, 5 months ago

Consider an electromagnetic wave. There are no considered charges, because there are no charges. Therefore, all considered charges are at rest; however, there's magnetic field present, so A is incorrect.

B is correct, but magnetic field isn't produced by moving charges only; it's also produced by time-varying electric field.

Jakub Šafin - 6 years, 5 months ago

Assertion & Reason

1 solution

0 pending reports