- #1
eprparadox
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Homework Statement
What potential difference is needed to stop an electron having an initial speed of 4.2*10^5 m/s?
Homework Equations
W = delta K
W = q*delta V
The Attempt at a Solution
So I'm pretty sure that the potential difference should be negative in order to stop the electron, but I keep getting a positive answer (the correct magnitude, but incorrect sign).
I set delta K = q*delta V.
I know delta K will be less than zero since K(final) < K(initial) and q should also be negative since we're dealing with an electron. But this gives me a positive delta V.
Where am I going wrong?
Thanks in advance.