Debroglie's equation (mass and volume)

[006045281]

When we are solving a problem using the DebBroglie, equation how do we solve for velocity if we are given only the wavelength and not the mass?

[Vivian Kha 2J]

Hi! Can you give an example of this happening because if you aren't given the velocity or the mass, you can't really solve for either one with only the wavelength. If you only have the wavelength, you can use De Broglie to solve for p (momentum). But because momentum is mass*velocity, you can't solve for velocity without mass and for mass without velocity.

In case you're referring to problems that don't tell you the mass but tell you there's an electron involved, then you are given the mass. The mass you'll need for the De Broglie equation is the mass of the electron, which the equation sheet says is 9.109383 * 10^-31 kg.

I hope this answers your question, but please reach out if it didn't.