a system consist a ball of radius "r" carrying spherically symmentric  charge and the surrounding space filled with volume density=/r .alpha=constsnt r is the dis. from the centre of the ball  .

a)find the ball's charge at which the mag of elctricfield vector is independant of r outside the ball

b)how high is the field strength? permitivity of ball and surrounding is 1

Charge=

calculate E with gauss law.

hey i m not getting ur question

is the surrounding space filled with charge?

I THINK THE ANSWER THT IS THE CHARGE ON THE SPHERE SHOULD BE

 

plz... rate if answer is correct. u can ask further if u require the solution.

indrajeet sir plz  tell the soln.

spere has a radius "R"..r is the distance from the center.....this question is in iridov

idrajeet can u explain your solution

@sneha

ok now i got the question right.

I THINK NOW I HAVE TO CHANGE THE ANSWER AND PUT A SOLUTION.

TO CALCULATE THE ELECTRIC FIELD AT A POINT OUTSIDE THE SPHERE, DRAW A GAUSSIAN SURFACE THT IS A SPHERE OF RADIUS r THROUGH THE POINT.NOW INSIDE THIS GAUSSIAN SURFACE, THE TOTAL CHARGE WILL BE DUE TO CHARGE ON THE SPHERE WHICH IS LET US ASSUME Q AND OTHER DUE TO THE CHARGED MEDIUM. THE CHARGE DUE TO THE MEDIUM CAN BE CALCULATED AS BELOW.

let us assume a point at a distance r through which there is a sphere of width dr.

now charge dq will be

 now,            

solving this for E we will get

now for electric field to be free from r the second expression inside the brackets must be equal to zero.

 or,                     

i think this is the required charge on the sphere.

hope u understood the solution.

PLZ... VOTE IF SATISFIED WITH THE SOLUTION.