Calculating Charge and Electron Count of Dust Particle in Electric Field

[Kourtney0115]

Homework Statement

A small piece of dust of mass m = 1.6 g travels horizontally through an electric air cleaner in which the electric field is 508 N/C. The electric force on the particle is equal to the weight of the particle.
a)What is the charge on the dust particle?
b)If this charge is provided by an excess of electrons, how many electrons does that correspond to?

Homework Equations

E=F/q

The Attempt at a Solution

a. (1.6e-6 * 9.8)/508 = 3.1e-8
b. 3.1e-8/1.6e-19 = 1.94e11

 

[kuruman]

Hi Kourtney0115, welcome to PF. Is there an answer you are seeking? If so, what is the question?

 

[Kourtney0115]

I attempted questions a and b from my question i posted but when i put it into my online homework it says its incorrect. I wasnt sure what i was doing wrong.

 

[kuruman]

I attempted questions a and b from my question i posted but when i put it into my online homework it says its incorrect. I wasnt sure what i was doing wrong.

1.6 g = 1.6x10^-3 kg. You are off by three orders of magnitude. Otherwise, your method is correct.

 

[Kourtney0115]

The reason i used 1.6x10^-6 is because it is supposed to say 1.6 micrograms. the symbol didnt paste with the rest of the problem. sorry about that.

 

[Stonebridge]

If it's micrograms then it should be 1.6x10-9 kg. (=1.6x10-6 g)

 

[Kourtney0115]

Ok, thank you so much!

 

[kuruman]

Then 1.6 micrograms = 1.6x10^-6 grams = 1.6x10^-9 kg.

 

[Jayjubear]

Oh hi Purdue Physics 221. I just got done with this one.