Hello sir, sorry to bother you again

Hi :-)

wait, let me show you the question

my problem here is, they didn't mention who is doing the work here

What I did was simply integrate E.dl which is the work done by the field, and this came to be negative

however, some people argue that the work done should be positive, as it is some external agent that does the work. However, my idea was that if I put a negative charge in an electric field, it would move in the direction opposite to the field. The work would be done by the field itself, and the potential energy would increase. There is no external force involved

Integrating E.d𝓁 is the correct way to do this. If the work comes out negative then the answer is negative. That just means the charge is doing work as it moves i.e. its potential energy is decreasing.

( sorry work done is q E.dl )

thank you, doing that the answer is coming out to be -1 mJ

The sign of work is always a little ambiguous as it depends on how exactly you are defining the work i.e. is it work done by the charge or work done on the charge.

however, there is a lot of people claiming that it should be positive instead.

so in a sense, this question is somewhat wrong, isn't it ? in the sense that it is not defined properly ?

I suspect the examiner would accept both -1mJ and +1mJ.

The point is that you understand how to compute the work.

yes sir, thank you so much