# Homework Help: Electric field and work done

1. Jul 23, 2010

### jinx007

A charge of 3C is moved from infinity to a point X in an electric field. The work done in this process is 15 J. T electric potential energy at X is

A 45 V

B 22.5 V

C 15 V

D 5 V

E 0.2 V

should i use electric potential = Q/4 (Pie) X r^2
And which equation is related to which..i am confused..!!!!!!

2. Jul 23, 2010

### graphene

The answer options seem to just be the 'electric potential' and not 'electric potential energy'.

The question specifies, charge,q and work done,W(or energy) and is asking you for the potential,V at that point
Have you come across expressions relating q,V and W?

3. Jul 23, 2010

### jinx007

Yeahhh v=w/Q 15/3 5V

lolzz seem easy..but what intricate me is that when to use the equation q Q k /r^2 and the other equation..

4. Jul 23, 2010

### utkarsh009

well i have a suggestion for you. first, read the question carefully and note down all the bits of information. like in the above case: work done and charge. then think of an equation relating the information and the question. this will help a lot.