Finding deBroigle wavelength of a charged electron

[ParrotPete]

Homework Statement

Given an electron with total energy 1 KeV, determine it's deBroigle wavelength.

Homework Equations

E^2 = (mc^2)^2+(pc)^2
$$\lambda$$ = $$\frac{h}{p}$$

The Attempt at a Solution

(pc)^2 = E^2 - (mc^2)^2 <> p = ± $$\frac{1}{c}$$ $$\sqrt{E^2-(mc^2)^2}$$

What am I doing wrong?
When I plug in E = 10^3 eV and (mc^2) = 0.511 * 10^6 eV I get an imaginary result.

 

[Dadface]

Homework Statement

Given an electron with total energy 1 KeV, determine it's deBroigle wavelength.

Homework Equations

E^2 = (mc^2)^2+(pc)^2
$$\lambda$$ = $$\frac{h}{p}$$

The Attempt at a Solution

(pc)^2 = E^2 - (mc^2)^2 <> p = ± $$\frac{1}{c}$$ $$\sqrt{E^2-(mc^2)^2}$$

What am I doing wrong?
When I plug in E = 10^3 eV and (mc^2) = 0.511 * 10^6 eV I get an imaginary result.

I think the question is written incorrectly and that the 1 KeV is the kinetic energy of the electron and not its total energy.