How to Calculate the Effective Mass of Carriers?

[rwooduk]

Homework Statement

Homework Equations

The Attempt at a Solution

I understand you can calculate the effective mass by using the equation above. What I'm unsure about is the "calculate the effective mass of the carriers" part. A donor impurity would be near the conduction band, therefore do we simply use the equation for E_c in the question? A bit unsure.

 

[mfb]

I would expect that, but I'm not sure.