The field-line representation of the electric field in a certain region of space
ID: 2116988 • Letter: T
Question
The field-line representation of the electric field in a certain region of space is shown above. The dashed lines represent equipotential lines.
Question 1: At which point (A-D) in space is the electric field the weakest?
Question 2: Compare the work done moving a negative charge from A to B and from A to D. Which one requires more work?
(A) More work is required to move a negative charge from A to B than from A to D
(B) More work is required to move a negative charge from A to D than from A to B
(C) The same amount of work is required to move a negative charge from A to B as to move it from A to D
(D) Cannot determine without performing the calculation
Please explain answer.
Explanation / Answer
Electric Field is weakest at point D
Reason:
The work done formula is F.S
we know that from electric pottetial definition it is the work done from moving the unit positive charge
from infinity to that point . so the difference between two points x and y will give us the workdone for moving the particle across two of them......
so now why D ?
Because we can see that even for little displacement there will more amount of work done this can
be seen by comparing A and C . C need cover more distance to do same work as A but A need cover only a little distace. so we can say that in W=F.S becuse the value of S is less for A so the
force must be more Sa<Sc so Fa>Fc so similarly we can say that Fb>Fd. comparision for d and c
can be made by seeing the density of electric charge so the least density is at point D so we can conclude that the force is least at D.
The same amount of work is required to move a negative charge from A to B as to move it from A to D
Because B and D are on equi pottential lines tha work done will be same. (Conservation of
Energy )...........
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