AQA AS Physics A Unit 1 January 2012 Discussion

Was specific charge Charge per unit mass?

Specific Charge = charge / mass. Measured in Ckg^-1
If that's what you meant by your question.

50/70 for an A ?

I would of thought closer to 56/70 which is 80%

I would of thought closer to 56/70 which is 80%

Was specific charge Charge per unit mass?

I would of thought closer to 56/70 which is 80%

Thats the same as saying Charge per uni mass thou

dint matter that it was after the exam...they copletely missed out oscilloscopes lol

I put charge per unit mass for a particle. It is technically the same.
For the table on part one for the charge on the proton I put +1.6 x 10^-19 instead of +1. Is that technically right? My Physics teacher told me to always put that. s: but then again...

For difference between Ionisation and Excitation, I said this for 3 marks:

Excitation is when an electron gains energy from a collision/absorption and moves to a higher energy level from ground state
Ionisation involves the same as the above, except in this case, the electron gains enough energy to be removed from the atom.

Pair production: A photon interacts with matter (eg. a nucleus) and converts into a particle and its anitparticle, with the net change in energy being zero, and all the conservation laws (eg. charge momentum) being conserved.

Whaddya think?

You only ever put +1, -1, 0 when it says relative charge iirc. I don't recall it saying relative charge (did anyone else?), so what you put is technically correct and AQA messed up

I wrote for pair production something like the photon has twice the rest energy of the particles it is going to make. It interacts with matter and produces a particle and antiparticle pair, e.g. electron and a positron, which have half the energy of the photon.