Conversion units mystery. Am I wrong?

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SUMMARY

The discussion centers on calculating charge (Q) using the formula Q = W/V, where W is work and V is potential difference. The potential difference is given as 140mV, and the work required is 280μJ. The correct approach involves converting all units to joules and coulombs before performing the calculation, as dividing millijoules by millivolts yields coulombs, not millicoulombs. The user is advised to simplify the process by ensuring consistent units throughout the calculation.

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Homework Statement


The potential difference between two points is 140mV. If 280μJ of work are required to move a charge Q from one point to the other, what is Q?

Homework Equations


Q = W/V

The Attempt at a Solution


http://imgur.com/FDaQfb9
 
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Hi, welcome to PF!

Convert the potential difference to volts, and the work to joules. Dividing joules with volts, you get coulombs for the charge. mJ/mV is also coulomb.

ehild
 
You are assuming that mJ divided by mV gives mC. That's wrong, it gives C. In general, you have overcomplicated things too much. Just convert everything into J and C, compute the result, then convert it to any units you want.
 

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