Differentiate De Broglies Theorem

[ZedCar]

Homework Statement

Someone has written down in some notes about differentiating DeBroglies Theorem.

They've started with Px =h/λ
(That's P sub x)

Then they've simply said, this differentiated is:

ΔPx = [-h/(λ^2)]Δλ

How have they done this? What method? What have they differentiated with respect to?

Thank you!

Homework Equations

The Attempt at a Solution

 

[Toll]

respect to λ

P = h/λ

dP/dλ = (-1/λ^2) * h

dP = -(h/λ^2)dλ