00:02
Given that, given radius r is equal to 20 cm and total charge q is equal to 40 mc.
00:14
And area of this a is equal to pi r square.
00:19
Surface charge density according to the equation.
00:22
Surface charge density rho s is equal to q upon pi r square.
00:39
Consider our ring of charge at a radical distance r.
00:43
The charge contained in width dr so dq is equal to q is equal to rho s into 2 pi r e to dr is equal to 2 pi into rho s and r dr.
01:05
The potential at p is due to ray.
01:08
A is equal to aq upon 4 pi epsilon naught is equal to 2 pi rho s rdr upon 4 pi epsilon naught r square plus pi square 1 by 2.
01:33
Where a is equal to a is equal to r square plus x square whole power 1 upon 2.
01:42
So the potential due to entire disc v is equal to limit 0 to r dv is equal to rho s upon 2 epsilon naught and integration limit 0 to a r dr upon r square plus x square value of a to whole power 1 upon 2.
02:07
So, v is equal to rho s upon 2 epsilon naught into r square plus x square whole power 1 upon 2 and limit 0 to r.
02:21
So, v is equal to rho s upon 2 epsilon naught r square plus x square whole power 1 upon 2 limit 0 to r.
02:30
So, v is equal to rho s upon 2 epsilon naught into r square plus x square to whole power 1 upon 2 minus x.
02:40
And this is equation first.
02:42
After rho at s is equal to q upon phi r square is equal to 40 upon 3 .14 substituting values into 0 .2 whole square...