I'm currently working on tutorial problems for setting the q-point for bjt circuits. When talking about Vq I'm getting a bit confused though. If Iq is the quiescent current I can see where you would measure that. But across where would I be able to measure Vq? Is it across the output of the transistor? Or is it just an imaginary point that I can't actually investigate with a voltmeter on the circuit?

 

The q-point is a point on the transistor collector/load line, measured at the collector.

Watch this

 

The voltage on the x-axis is the voltage across the collector-emitter, VCE, i.e. the voltage at the collector with respect to the emitter .