Recent content by beesher

anyone?

Homework Statement (a) A sample of n-type Germanium contains 1023 ionized donors per cubic meter. Estimate the ratio at room temperature (300K) of the resistivity of this material to that of high purity intrinsic Germanium. The Electron hole product for Germanium is 1038m-6 and it can be...

Hi folks, I've recently been studying point defects, but I can't seem to come across how the formation of f-centres actually affects the density of a crystal. Does it increase or decrease the density? Thanks for any help/ ponters

Cheers Ok, thanks very much I'll get it finished tomorrow. Oh and yes the 68R is simply referring to Ohms. Edit; Still can't figure it out :(

Circuit.. Here's a circuit diagram if that can give anyone a better idea of the circuit in question.

Homework Statement an npn transistor is used to drive a constant current I through three ‘white’ LEDs, connected in series. If the required current value is I = 25 mA, and the current-gain of the transistor is β = 300, find the value of the resistor R, giving your answer to 3 significant...