Photoelectric effect

Homework Statement

What potential difference must be applied to stop the fastest photoelectrons by a nickel surface under the action of ultraviolet light of wavelength 220 nm? work function of nickel is 5.00eV.

Homework Equations

h[c]/[$$\lambda$$] = $$\Phi$$ + eV

The Attempt at a Solution

h=6.6x10^-34 Js
c=3.0x10^8 m/s
$$\lambda$$=200x10^-9 m
$$\Phi$$=5.00eV
e=1.6x10^-19
V=?

[6.6x10^-34(3.0x10^8)]/[/200x10^-9] = 5.00 + 1.6x10^-19V
9.9x10^-37 = 5.00 + 1.6x10^-19V
9.9x10^37/5.00 = + 1.6x10^-19V
1.98x10^37 / - 1.6x10^-19 =V
v= 1.23x10^.18m/s

not sure if this is right

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