Worksheet: Electric Potential of a Charged Disk

Practice calculating how the electric potential around a charged disk varies with position relative to the disk. Practice identifying the symmetries that help to simplify calculations.

Q1:

A CD disk of radius is sprayed with a charged paint so that the charge varies continually with radial distance from the center in the following manner: .

Find the potential at a point 4.0 cm above the center.

Q2:

A thin conducting plane has a charge density of C/m². An electron is placed 0.80 cm above the the plane. What is the magnitude of the acceleration of the electron?

A m/s²
B m/s²
C m/s²
D m/s²
E m/s²

Q3:

Two square conducting plates of side length 50.0 cm are placed parallel to each other 9.0 mm apart. What magnitude electric field is generated between the plates after electrons are transferred from one plate to the other?

A N/C
B N/C
C N/C
D N/C
E N/C

Q4:

A proton moves horizontally at an initial speed directly toward a large, positively charged plate that has a surface charge density of C/m². What is the proton’s horizontal displacement from the plate at the point where it comes instantaneously to rest?

Q5:

A thin conducting plate 4.00 m on a side is given a total charge of µC. A point is located at the center of the plate 2.00 cm above its surface.

What is the magnitude of the electric field at the point ?

A N/C
B N/C
C N/C
D N/C
E N/C

What is the magnitude of the electric force on an electron at the point ?

An electron is moved 1.00 cm vertically downward from the point . What is the work done by the electric field on the electron?