Are you suppose to know this?What else do you need to know about potential bias because its a topic I have never come across in a diode and in the specimen it asked it and said that current flows past the ammeter when the current in a diode is very high protecting the ammeter.i have done where the current starts flowing in the direction the diode is stopping at a high negative voltage though.The specimen is so hard I got 55/70-be careful if you do it though because some of the answers are wrong.
Potential Dividers formulas are unnecessary because the v out basically represents the voltage supplied to the component its as simple as that but AQA try to pretend its a big ew topic but its not really.