# Homework Help: How many electrons make up a charge of -15.0 uC?

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1. May 3, 2015

### Kaylee Hamann

So I've already got some help on this one, now I have a different question pertaining to this equation.

I know
N=q/e
e=-1.6x10^-19
q=-15x10-6

so I tried:

N=(-15x10-6)/-1.6x10^-19
N=-156/-1.6x10^-19
N=9.74
~that was wrong

So I thought maybe this:
N=(-15x10-6)/-1.6x10^-19
N=--60/-1.6x10^-19
N=3.8x10^-18
~also wrong

so I thought maybe I need to use the full form of e=-1.602x106-19

N=(-15x10-6)/-1.602x106-19
N=-156/-1.602x106-19
N=9.74x10^-18
~that was wrong

So I thought maybe this:
N=(-15x10-6)/-1.602x106-19
N=--60/-1.602x106-19
N=3.75x10^-18
~also wrong

Last edited by a moderator: May 4, 2015
2. May 3, 2015

### haruspex

What is xa*xb?
What is xa/xb?
What is 10-6 / 10-19?

3. May 3, 2015

what?

4. May 3, 2015

### haruspex

I thought my questions were very clear.
What do you get if you multiply x to the power of a (xa) by x to the power of b (xb)?

5. May 3, 2015

### Kaylee Hamann

I think its x^a+b

6. May 3, 2015

### Kaylee Hamann

What is x^a*x^b = x^a+b
What is x^a/x^b = x^a-b
What is 10^-6 / 10^-19 = 10^-6-(-19) = 10^-25

7. May 3, 2015

### haruspex

Close, but you went wrong at the last step. What is -6-(-19)?
(And you really should use parentheses correctly: x^(a+b) etc.)