Question

Which of the following statements is/are true about Gaussian surfaces?

i. Gaussian surface is the name for a closed surfaces used when calculating flux in Gauss’ Law
ii. A Gaussian surface can have any shape (as long as it is closed)
iii. Like defining your system in energy problems, you can choose any shape or position of Gaussian surface in a problem
iv. It is easy to calculate flux with any Gaussian surfaces you choose
i only
i, ii, iii, and iv
i, ii, and iii only
i and ii only
i and iii only

Answer 1

It can have any shape BUT although it is easy to calculate E as a function of radius from a charge with a spherical surface where the E is constant over the surface and perpendicular to the surface, calculating the E field over the surface of a cube for example with a charge at the center would not be easy because it is not constant over the surface and is only perpendicular to the surface at the centers of the sides of the cube. iv is therefore totally false.