AQA Physics Unit 1 PHYA1 20th May 2013

for the plot the rms voltage on the graph..did you have to plot it when the voltage was negative also? seems it would be the case as it was worth 2 marks..forgot to do it lol oops

Well no. But I hope you get what you want. Amen.

Crap, I think you do. I didn't do that. diojsoidjs

I got that as well, did you do V/I=R then add 5000 to it and then do 90000-Ans

Crap, I think you do. I didn't do that. diojsoidjs

Yeh S1 was a little weird, but okay
Good luck! I abandoned History at GCSE, too much writing!!

It was plot DC voltage not rms

It was plot DC voltage not rms

Isn't rms the equivalent DC voltage? So would one line be ok?

Not very related but does anyone know the rough raw mark to ums conversion for the ISAs?

Hi guys,

The test was okay; didn't expect that 6-marker!

These are my answers. I'm not sure if they are right.

Q1
28 n, 20 p, 18 e
charge=+3.2x10^-19
specific charge=4.0x10^6 Ckg^-1

Q2
D quark, W+ boson, positron, electron neutrino
Weak interaction
B was the exchange boson
photon has infinite range, W+ has limited range
Charge conserved, baryon number conserved

Q3
6 marker, hadrons experience strong and weak, leptons weak only. hadrons are protons neutrons, leptons are electrons, neutrinos. both experience weak, both have antiparticles, both have charge. hadrons include baryons and mesons etc
proton, antiproton
antiparticles have opposite charge sign

Q4
E depends on f. 1 electron absorbs 1 photon. KE=hf-work function. Max value. KE is less than max if work is done on deeper electrons.
work function=1.8eV
frequency=4.4x10^14 Hz
frequency reduced, less energy, less kinetic energy
intensity increased, more photons per second, more electrons per second.

Q5
peak to peak=128V
peak=64V
RMS=45(.3)V
frequency=100Hz
DC= straight ine at 45V
Oscilloscope, y-gain is same as before, 20Vdiv^-1. Change time base to include 2 cycles. 1 cycle=10ms, 2 cycles=20ms, so 2msdiv^-1.

Q6
6.3V
5.7V across 2 ohm resistor
2.85A across 2 ohm resistor
1.35A across unknown resistor
4.2 ohm resistance
2.86 ohms total resistance
power: Internal resistor=26.5W, 2 ohm resistor=16.2W, other resistor=7.7W
energy conserved: battery power-total power dissipated=0
50.4-26.5-7.7-16.2=0

Q7
6.7x10^-5 A
1/3 V
resistance of LDR decreases, so greater proportion of pd across resistor, reading increases
30000 ohms resistance.

Tell me if there are any issues.
Good Luck!

PS, any ideas for grade boundaries?

It's only one horizontal line as a direct current doesn't reverse direction remember. It just flows in one conventional direction. If it were two horizontal lines, that would mean a current is flowing simultaneously in both directions which, well, is baffling.

question 4, about the frequency being reduced, surely this has no effect unless the frequency is below the threshold frequency?

> I messed up and put Beta minus decay, so W- Boson, Anti-neutrino and electron, how many marks do you think this has cost me?

​so annoyed.

True. Not sure why it was 2 marks then, but at least I got em.

in the specific charge question for number 1, do you have to include the mass of the electrons as their mass is almost negligible? you get the same answer (4.0x10^6) if you don't.