Please help

Thread Starter


Joined Jan 23, 2004
At the moment I am struggling with these two questions.
First question is this

1. a) A thunderstorm contains electric charges of +10 C at a height of 7 km and -10 C at a height of 2km. If the charges are considered to be at a point, find the force between the charges and state whether the force is attractive or repulsive.

I have done the part a but the part b is difficult for me.

B) If an aircraft starts in the east and flies through the
storm at a height of 4 km, compute the electric field at the aircraft when it is 5 km west of the storm.

Second question is

4) Calculate the peak value of the displacement current density for the following cases:
(i) a field in a high voltage cable with εr = 4 and electric field E = 400 sin(100πt) kV/m
(ii) a radio wave of frequency 1 MHz and E=1 µV/m
(iii) a laser beam of frequency 1015 Hz and E = 30 kV/m