Gauss's Law

Which of the following must be true for a Gaussian surface through which the net flux is zero?

1. There are no charges inside the surface.

2. The net charge enclosed by the surface is zero.

3. The electric field is zero everywhere on the surface.

• I only

• II only

• I and II only

• I, II, and III

Spheres A, B, and C are arranged on the xy

xy-axis as shown. What is the electric flux through a Gaussian sphere of radius 80cm

80cm centered on the origin?

• $-\frac{4q}{\epsilon_0}$

• $-\frac{2q}{\epsilon_0}$

• $-\frac{q}{\epsilon_0}$

• $\frac{q}{\epsilon_0}$

Charges of +Q and +q are situated as shown above. A Gaussian surface is concentric with the +Q charge, with point P located on the Gaussian surface. Which of the following statements below is not necessarily true?

• The electric flux through the surface depends only on the +Q charge.

• The electric flux is the same everywhere on the Gaussian surface.

• The electric field at point P depends only the +Q charge.

• Every point on the Gaussian surface has a different electric field.

The electrc field at a perpendicular distance from a long, straight current-carrying wire is directly proportional to:

• $\ln\left(r\right)$
  

• $r^2$

• $\frac{1}{r}$

• $\frac{1}{r^2}$

The figure below shows a thin, conducting sheet that can be assumed to be infinitely large. Point P is on the sheet in its center. Point A is above the sheet, at a distance x away, and point B is above the sheet a distance of 4x away.

• E/16

• 4E

• E/4

• E

A parallel-plate capacitor consists of 2 charged conducting plates of equal area, A. Each plate has a charge magnitude Q. The upper plate has a charge of and the lower plate has a charge of . The plates are separated by a distance . Which of the following is a correct application of Gauss’s law to find the electric field between the plates?

• $EA=\frac{Q}{\epsilon_0}$

• $2EA=\frac{Q}{\epsilon_0}$

• $EA=0$

• $2EA=\frac{Q}{A\epsilon_0}$

An electron is moving in the direction shown above and is accelerating toward the disk, which has an electric charge. Which of the following makes a correct claim about the electric field produced by the disk and gives evidence to support this claim?

• The electric field is to the left, because the electron accelerates to the left.

• The electric field is to the right, because the electron accelerates to the left.

• The electric field is toward the top of the page, because the electron was originally moving toward the top of the page.

• The electric field is toward the bottom of the page, because the electron was originally moving toward the top of the page.

Two negative charges A and B are placed at the corners of equilateral triangle. What is the magnitude of the net electric field at point C?

• $\frac{\sqrt{2}KQ}{r^2}$

• $\frac{\sqrt{3}kQ}{r^2}$

• $\frac{kQ}{r^2}$

• $\frac{\sqrt{5}kQ}{r^2}$

Who made Gauss's Law?

• Sir Isaac Newton

• Chad Bruhswick Gauss

• Carl Friedrich Gauss

• Michael Faraday