|

Electricity

Blazing goIITian

 Joined: 18 Dec 2006 Post: 305
7 May 2007 13:22:58 IST
0 People liked this
14
875
Soap bubble
Engineering Entrance , Medical Entrance , AIPMT , JEE Main , AIIMS , JEE Advanced , Physics , Electricity

If a soap bubble ,having radius r, is charged to a charge density  and its radius is increased to R ,then R is equal to ................. [ T is the surface tension ]

New kid on the Block

Joined: 5 May 2007
Posts: 28
8 May 2007 07:02:51 IST
0 people liked this

hey..i hav a quest on soap bubble too..if neone noes d ans ..plzz....if a soap bubble is givn a -ve charge its rad will inc/dec/remain same???

Blazing goIITian

Joined: 18 Dec 2006
Posts: 305
8 May 2007 12:40:12 IST
0 people liked this

????

Cool goIITian

Joined: 20 Apr 2007
Posts: 92
8 May 2007 12:50:45 IST
0 people liked this

ok, let me think over it
give me 5 min...................

Cool goIITian

Joined: 20 Apr 2007
Posts: 92
8 May 2007 12:58:10 IST
0 people liked this

is the ans something like
R^3 = (sigma)^2 * r^4 / 4*E0*T
where E0 is epsilon
tell me, so that i can know if i m on the right track

Blazing goIITian

Joined: 18 Dec 2006
Posts: 305
8 May 2007 13:02:43 IST
0 people liked this

No its not..............
howevr thanx 4 giving it a try..........

Cool goIITian

Joined: 20 Apr 2007
Posts: 92
8 May 2007 13:03:59 IST
0 people liked this

tell me the ans. then
it should be related to it..............

Blazing goIITian

Joined: 18 Dec 2006
Posts: 305
8 May 2007 13:09:31 IST
0 people liked this

R= 8 Eo T/^2

Forum Expert
Joined: 1 Dec 2006
Posts: 2108
8 May 2007 13:16:11 IST
2 people liked this

here's nothing...

the electrostatic pressure on a bubble when a charge density  is given to a bubble of radius R =  2 / 2 0
so equating it with 4T / R , we have R = 8 0 T/^2

Forum Expert
Joined: 19 Feb 2007
Posts: 3836
8 May 2007 13:19:40 IST
1 people liked this

fr that -ive charge qs , radius of soap bubble will always increase whether it is given +ive or -ive charge.........

Forum Expert
Joined: 1 Dec 2006
Posts: 2108
8 May 2007 13:27:07 IST
2 people liked this

for any small area dS on the sphere, net E = 0
thus E1 + E2 = 0 (in vector form)
=> |E1| = |E2|
now field lines will be almost perpendicular to dS
thrfore at dS
E A = A   / 0
=>     E  =    / 0
=>  E1 = E2 =   / 20
thrfore force on dS = dq E
= ( dS ) ( / 20)
=> P = F/ dS =  2 / 2 0

Hot goIITian

Joined: 9 May 2007
Posts: 104
9 May 2007 13:55:14 IST
0 people liked this

hey himanshu can u plz explain y will it always increase?

Cool goIITian

Joined: 6 May 2007
Posts: 58
9 May 2007 14:06:58 IST
0 people liked this

The surface has the same kind of charge... so each part will repel... so the radius should always increase

Forum Expert
Joined: 19 Feb 2007
Posts: 3836
9 May 2007 14:14:27 IST
0 people liked this

lemme correct a little

charge gets deposited on the surface (the charge we give)
so it will repel and radius will increase

New kid on the Block

Joined: 25 Apr 2007
Posts: 19
13 May 2007 09:06:46 IST
0 people liked this

radius of soap bubble increases on account of mutual repulsion between elementary charges on surface of bubble.

 Some HTML allowed. Keep your comments above the belt or risk having them deleted. Signup for a avatar to have your pictures show up by your comment If Members see a thread that violates the Posting Rules, bring it to the attention of the Moderator Team

## For Quick Info

Name

Mobile

E-mail

City

Class

### Find Posts by Topics

Physics

Topics

Mathematics

Chemistry

Biology

Institutes

Parents Corner

Board

Fun Zone

Vertical Limit

Top Contributors
All Time This Month Last Week
1. Bipin Dubey
 Altitude - 16545 m Post - 7958
2. Himanshu
 Altitude - 10925 m Post - 3836
3. Hari Shankar
 Altitude - 9960 m Post - 2185
4. edison
 Altitude - 10815 m Post - 7797
5. Sagar Saxena
 Altitude - 8625 m Post - 8064