Why does the charge inside the closed surface of a gaussian surface contribute to electric flux. Why doesnt it pass through as in the case of electric flux due to a charge that is situated outside? Ans: When we find electric flux through a surface, then we consider the charge enclosed by the surface. This is done because Gauss' law is defined in terms of charge enclosed. So, a charge that is situated inside the surface contributes to the flux. Thank you for a quick response. However, the answer provided by you doesnt clarify my doubt. There was a clear reasoning provided in the video lesson, why charge outside does not contribute to the flux. The electric field lines produced by a charge situated outside pass through the gaussian surface. Therefore, the question iam asking is that, what happens in the case of charge situated inside.

CBSE Class 12-science Answered

Why does the charge inside the closed surface of a gaussian surface contribute to electric flux. Why doesnt it pass through as in the case of electric flux due to a charge that is situated outside?

Ans: When we find electric flux through a surface, then we consider the charge enclosed by the surface. This is done because Gauss' law is defined in terms of charge enclosed. So, a charge that is situated inside the surface contributes to the flux.

Thank you for a quick response. However, the answer provided by you doesnt clarify my doubt. There was a clear reasoning provided in the video lesson, why charge outside does not contribute to the flux. The electric field lines produced by a charge situated outside pass through the gaussian surface. Therefore, the question iam asking is that, what happens in the case of charge situated inside.

Asked by Anirudh | 10 Aug, 2017, 12:30: PM

Expert Answer

We appreciate your feedback. Based on the current question, following is the answer that we feel will clear your doubt.

1) If you see a charge outside the surface, then for the surface the flux through it passes "IN" from some points and "OUT" from some points. Refer the screenshot of the video lesson.

2) Due to this, the net flux cancels out and it does not contribute to the flux through the surface.

3) Now, if we consider a charge inside, then its field lines will either be inwards (negative charge) or outwards (positive charge).

4) So, all the points on the Gaussian surface will receive field lines (flux) either "IN" or "OUT". Hence, in this way a charge inside the closed surface contributes to the net flux.

Answered by Romal Bhansali | 10 Aug, 2017, 02:36: PM