Flag Electrostatics> distance of x...
question mark

two point charges +36 and -16 microcoulumb are placed 10 cm apart. at a point x, there is no resultant force on positive charge. the distance of x from +36 microcoulumb charge is

eshita paul , 13 Years ago
Grade 12
anser 2 Answers
Chetan Mandayam Nayakar

Last Activity: 13 Years ago

if there is no resultant force, it implies that forces due to the charges are equal and opposite. this can happen only on the line connecting the two charges. this cannot happen between the two charges for obvious reasons. larger charge exerts greater magnitude force,because of which resultant force on positive charge is zero only on the line connecting two charges such that the zero force point and the -16 microcoulomb charge lie on the same side of the +36 microcoulomb charge

(1/4pik)(36/(x^2))=(1/4pik)(16/(x-10)^2)), ((x-10)^2)/16 =(x^2)/36,((x-10)^2)/4= (x^2)/9

(x-10)/2 =±x/3,3x-30=±2x, x=30 or 6, x>10, therefore x=30 cm

Askiitians_Expert Yagyadutt

Last Activity: 13 Years ago

Hello Eshita !

 

Good morning :)

 

Well this is very easy question ...try to understand the steps of solving ...

 

First of all given that distance between the two charge is 10 cm ..

And if you will place the charge between the two charges ...then it will always experience a force..I mean to say that between the two charges there can't be any point where force is zero .. Understand by figure

 

So the only options is to put the charge either side of the two charges . okay ..

 

Cosider this figure ..

 

Then net force on the charge is ...

 

K 36/ (10+x)^2  - ( K 16/ (x)^2 ) = 0   ( because we have to find x for which net force is zero) ..

 

36(x)^2 = 16(10+x)^2

 

6x = 40 + 4x

 

x = 20 cm ..

 

Hence from 36 columb charge distance is ...10+20 = 30 cm ...Refer the figure ...

 

 

 

547_23490_Untitled.gif

 

Ask further your doubts...

 

Regards

Yagya

Askiitians _expert

Provide a better Answer & Earn Cool Goodies

star
LIVE ONLINE CLASSES

Prepraring for the competition made easy just by live online class.

tv

Full Live Access

material

Study Material

removal

Live Doubts Solving

assignment

Daily Class Assignments


Ask a Doubt

Get your questions answered by the expert for free