# Electric Field of ping pong ball of mass

• llamajuice
In summary, a ping pong ball of mass 3.0 x 10^-4 kg hangs from a light thread 1.0m long, between 2 vertical parallel plates 10.0cm apart. When the potential difference across the plates is 420 V, the ball comes to equilibrium 1.0 cm to one side of its original position. The electric field strength between the plates is 4200 N/C. The tension in the thread can be calculated using the free body diagram and is equal to 2.94 x 10^-3 N. The magnitude of the electric force deflecting the ball can be found by considering the angle between the thread and the vertical, and is equal to 0.1 times
llamajuice

## Homework Statement

A ping pong ball of mass 3.0 x 10^-4 kg hangs from a light thread 1.0m long, between 2 vertical parallel plates 10.0cm apart. When the potential difference across the plates is 420 V, the ball comes to equilibrium 1.0 cm to one side of its original position.
a) Calculate the electric field strength between the plates.
b) Calculate the tension in the thread
c) Calculate the magnitude of the electric force deflecting the ball..
d) Calculate the charge on the ball.

## Homework Equations

Epsilon = (kq)/r^2
Electrical Force = (kq1q2)/r^2
V = (kq)/r

## The Attempt at a Solution

a)Epsilon = V/r = 420V/0.10m = 4200N/C

b) Fg = mg = (3.0 x 10^-4 kg)(9.8m/s^2) = 2.94 x 10^-3N

c)I'm not sure how to do the rest.

Here's what the diagram looks like.

#### Attachments

• figure 3 pingpong ball.bmp
254.5 KB · Views: 757
b) is wrong.
Draw a free body diagram with the ball 1cm away from one of the plates, show all the forces acting on the ball.

Something like this?

#### Attachments

• FBD Pingpong.bmp
228.6 KB · Views: 767
b) alpha is angel between the thread (when V = 420V) and vertical
the tension in the thread (T):
Because of equilibrium condition:
Fg/T = cos(alpha) --> T = Fg/cos(alpha)
c) the magnitude of the electric force deflecting the ball
Fe/Fg =tan(alpha)~alpha --> Fe = Fg.0.1
d) Fe=q.E --> q= Fe/E = Fe.r/V

the FBD looks alright.

Notate the angle between the string & the vertical.

Then balance the forces acting on the ball.
That should solve b,c & d. :)

abreault27

## What is the electric field of a ping pong ball of mass?

The electric field of a ping pong ball of mass depends on the charge of the ball and its distance from other charged objects. It can be calculated using the formula E = kQ/r^2, where k is the Coulomb's constant, Q is the charge of the ball, and r is the distance from other charged objects.

## How does the electric field of a ping pong ball of mass affect its motion?

The electric field of a ping pong ball of mass can affect its motion by exerting a force on the ball. If the ball has a positive charge, it will be repelled by other positively charged objects and attracted to negatively charged objects. This force can cause the ball to accelerate in a certain direction.

## Can the electric field of a ping pong ball of mass be manipulated?

Yes, the electric field of a ping pong ball of mass can be manipulated by changing the charge of the ball or the distance between the ball and other charged objects. This can be done by using an external source of charge, such as a battery, or by physically moving the ball closer or farther away from other objects.

## What factors can influence the electric field of a ping pong ball of mass?

The electric field of a ping pong ball of mass can be influenced by factors such as the charge of the ball, the charge of other nearby objects, and the distance between the ball and those objects. Additionally, the material and shape of the ball can also affect the electric field.

## Is the electric field of a ping pong ball of mass constant?

No, the electric field of a ping pong ball of mass can change depending on the factors mentioned above. If the charge of the ball or the distance between the ball and other objects changes, the electric field will also change. However, if these factors are kept constant, the electric field will remain constant as well.

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