What is the net charge after adding electrons?

In summary, a metal sphere with a charge of +7.0 µC has 8.00 x 10^13 electrons placed on it. To find the net charge, we multiply the charge of an electron (-1.6 x 10^-19 C) by the number of electrons and add it to the original charge. In this case, the net charge is -5.8 µC. When dealing with significant figures, it's important to pay attention to the number of digits in the original values and use the correct number of significant figures in the final answer.
  • #1
rcmango
234
0

Homework Statement



A metal sphere has a charge of +7.0 µC. What is the net charge after 8.00 10^13 electrons have been placed on it?
in µC


Homework Equations





The Attempt at a Solution



I believe that the charge of an electron is: -1.6 x 10^-19 C
and there are 8 electrons,

so -1.6 x 10^19 C * 8.00 x 10 ^13 electrons right?

then I add it to 7 uC? well I'm having trouble with the sigfigs, I got 5.72 uC I don't believe that is correct.

please help.
 
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  • #2
Do you have a rounding error? I am getting -5.8µC.
 
  • #3
ah, I see from your answer. Sometimes it just takes someone else.

it was my sign! it has to be negative.

Thankyou!
 
  • #4
also, when i get the answer, after multiplying the electrons, does +7.0 uC have sigfigs? i can't seem to figure out why my calculater won't give me anything past 1.28 x 10^33 i believe.
 
  • #5
rcmango said:
also, when i get the answer, after multiplying the electrons, does +7.0 uC have sigfigs? i can't seem to figure out why my calculater won't give me anything past 1.28 x 10^33 i believe.

Sorry I don't understand your calculator comment. 7.0µC has 2 significant figures, and it means [itex]7.0*10^{-6}[/itex]C. 7.00µC would be 3 sig figs, and 7µC would be 1 sig fig.
 

What is the net charge?

The net charge is the overall electric charge of an object or system. It is determined by the sum of all the positive and negative charges within the object or system.

How is net charge calculated?

Net charge is calculated by adding up all the positive charges and subtracting the sum of all the negative charges. The resulting value will be the net charge.

What is a positive charge?

A positive charge is an excess of protons, which have a positive charge, compared to the number of electrons, which have a negative charge. Objects with a positive charge will repel other positively charged objects and attract negatively charged objects.

What is a negative charge?

A negative charge is an excess of electrons, which have a negative charge, compared to the number of protons, which have a positive charge. Objects with a negative charge will repel other negatively charged objects and attract positively charged objects.

What is a neutral charge?

A neutral charge is when there is an equal number of protons and electrons, resulting in a net charge of 0. Objects with a neutral charge will not be affected by electric fields.

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