A level physics help

This is just a 1 mark question so it's probably me being an idiot, but I don't understand this at all :redface:

So there's a transmission cable, of +200kV surrounded by equipotentials at 195,190 and 185kV.

The 195kV equipotentials is 5mm away from the surface of the 200kV transmission cable. Use this information to choose the best estimate of the electric field strength on the surface of the cable.
The options are: 40V/m, 1x10^-3 V/m, 1x10^6V/m, 4x10^7V/m.

Now my answer was the last option, because I assumed that the field would be uniform over that 5mm, and so I did 200kV divided by 5mm..... Why is this wrong? The answer is apparently 1x10^6.

Thanks!

Reply 1

Darnellc018

Just drop Physics it's too hard

Bump

I'm probably not the best help as I don't do this topic (this year anyway :P) but the values all look pretty different, I'd guess the one that sounds like it's most realistic.

I probably wasn't the best help but if you still need help try posting it in the physics forum http://www.thestudentroom.co.uk/forumdisplay.php?f=131

Reply 4

topgun41

Original post by k4l397