Find the charge on the outer surface

[Fatima Hasan]

Homework Statement

Homework Equations

$E=\frac{kQ}{r^2}$

The Attempt at a Solution

The answer is "A".Right ?

 

[BvU]

Hello Fatima,

PF is not intended for stamp-approvals. If you convince yourself that -9 nC is the right answer, then that IS your answer for this exercise !

And why shouldn't it be the right answer ?

 

[BvU]

Yeah, well...

 

[Fatima Hasan]

Hello Fatima,

PF is not intended for stamp-approvals. If you convince yourself that -9 nC is the right answer, then that IS your answer for this exercise !

And why shouldn't it be the right answer ?

I was not pretty sure. Just wanted to confirm my answer. Sorry for multiple questions but my exam is after hours. I wish I have not broken the forum rules. Thanks

 

[BvU]

Best of luck for your test!

 

[ehild]

Homework Statement

View attachment 223911

Homework Equations

$E=\frac{kQ}{r^2}$

The Attempt at a Solution

View attachment 223912
The answer is "A".Right ?

You wrote that Q=1 nC and then that Q=-10+1 =-9 nC. These are wrong, although the answer "A" is correct. Pay more attention!

 

[Fatima Hasan]

You wrote that Q=1 nC and then that Q=-10+1 =-9 nC. These are wrong, although the answer "A" is correct. Pay more attention!

$Q_0=-10+1=-9nC$

 

[ehild]

$Q_0=-10+1=-9nC$

-10+1 is not -9 nC . Write out the units at both sides of an equation.