Calculating work done by an electric field

[crh]

Homework Statement

How much work does the electric field do in moving a proton from a point with a potential of +155V to a point where it is -75V. Express your answer in both joules and electron volts.

Homework Equations

W = -qV

The Attempt at a Solution

I know that q=(1.6E-19) but I am not for sure how to go about incorporating my two potentials. Can someone give me some help? I thank you in advance!

 

[Hootenanny]

Homework Equations

W = -qV

Perhaps it would help if the equation was written thus:

W = -q\Delta V

In other words, the work done by the electric field on the charged particle is the negative product of the charge and the change in potential.

 

[crh]

Ok I think I figured it out. Tell me if I am wrong.

W = -qV, but V is potential E (PE), so therefore V = (PE2-PE1)

so...

W = -(1.60E-19C)(-80V) = 1.28E-17 J
and
= -(1e)(-80V) = 80eV

did I go about this right?

 

[Hootenanny]

Ok I think I figured it out. Tell me if I am wrong.

W = -qV, but V is potential E (PE), so therefore V = (PE2-PE1)

so...

W = -(1.60E-19C)(-80V) = 1.28E-17 J
and
= -(1e)(-80V) = 80eV

did I go about this right?

You're on the right lines but be careful when calculating the change in potential.

 

[crh]

Are you meaning scientific notation?

 

[Hootenanny]

Are you meaning scientific notation?

Nope, something somewhat simpler than that. What is the difference between -75 and +155?

 

[crh]

oh it needs to be -230V.

 

[Hootenanny]

oh it needs to be -230V.

Much better