Charge Distributions#

Two thin rings of radius R and charges Q1=Q and Q2=Q are centred along the x-axis as shown in the figure below.

Two thin rings of radius R are concentric with the x axis. One ring of charge Q1 equal to Q has an x position of -d, while the other ring of charge Q2 equal to -Q has an x position of 0. A point P is shown at some positive value of x with a distance r1 to the ring of charge Q1 at an x position of -d.

Part 1#

Write an expression in terms of x, d and R for the distance, r1, for the distance of any point on ring 1 from point P. Note that this is a right-angled triangle so you can use the pythagorean theorem.

Use the following table as a reference for each variable:

For

Use

R

R

d

d

x

x

k

k

Q

Q

If the answer is 0, enter “zero”.

Answer Section#

Part 2#

Write an expression for the electric potential at point P due to the two thin rings in terms of Q, R, d and x.

Use the following table as a reference for each variable:

For

Use

R

R

d

d

x

x

k

k

Q

Q

If the answer is 0, enter “zero”.

Answer Section#

Part 3#

From your expression for the potential energy find the electric field at point P. Note that it points along the x-axis, and remember to use the chain rule.

Use the following table as a reference for each variable:

For

Use

R

R

d

d

x

x

k

k

Q

Q

If the answer is 0, enter “zero”.

Answer Section#

Part 4#

When x=d2 evaluate the electric potential.

Use the following table as a reference for each variable:

For

Use

R

R

d

d

x

x

k

k

Q

Q

If the answer is 0, enter “zero”.

Answer Section#

Part 5#

When x=d2 evaluate the electric field.

Use the following table as a reference for each variable:

For

Use

R

R

d

d

x

x

k

k

Q

Q

If the answer is 0, enter “zero”.

Answer Section#

Attribution#

Problem is licensed under the CC-BY-NC-SA 4.0 license.
The Creative Commons 4.0 license requiring attribution-BY, non-commercial-NC, and share-alike-SA license.