Question

The point charges Q and -2Q are placed some distance apart .if the electric field intensity at Q is E then what is the electric field at -2Q?

Answer 1

The electric field intensity is the intensity or the force that is experienced due to a unit charge present. Now in the question  we are given that the electric field intensity due to charge -2 Q on point Q is E.  Since F is directly proportional to q we can say F= kqE where K is the proportionality constant now we write the equation in terms of E we get  

$E=\frac{F}{k q}$

Now putting the value 2Q we get $E=\frac{F}{k 2 q}$,  which is half of the year experience that q hence we can  say at point 2Q  electric field intensity will be  ½ E.