Edexcel Physics (Salters Horners) PSA6 Synoptic - 17th June 2008

Totally mucked up my units on the graph.

I thought the paper was alright all in all.

The last question I talked about the Doppler Effect and Red Shift for the changing f.

Also mentioned what e-mag waves are [i.e. transverse]
Talked about optical fibres carrying digital signals.
And talked about Frequency division multiplexing which was the idea of the last few sentences.

Thought that q was fairly standard.

Didn't like the Voltage induced graph...I just drew a curve pi/2 radians out of phase, so it was like a cos graph. [dunno if that's right]

Graph was standard...+/- 0.005mA on the accuracy for the 1st part?

That's all I can remember now.

That's good, that's 2 more people with a decreased amplitude so I'm happy

Also, how/whether induction would occur in the human body and some other *******s. I got all my units on the graph question but I can't remember the k value. I do remember getting (R/V)^2 as 5x10^6 per amp^2, giving me around 447 ohms for the body fat.
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36/60 to get an A? That's barely 60%, is this media studies? Everyone in this thread sounds like they easily did that.

Trust me i didnt. Although i thought it was 80% for an A???

That's 80% of UMS marks needed for an A the raw marks change depending on the difficulty of the exam

Confuuuussed!!!!!

Yes, the reading on the oscilloscope decreases in amplitude because the current passing through the body creates a magnetic field opposing that creating it (Lenz's Law), so the coil experiences less magnitude of changing flux, so induced voltage is lower. Thought the radioactivity body fat question was hard, I got 0.042m^3 (ratio of activities is inverse ratio of volumes). When plotting the induced voltage given flux variation, where flux was max. or min, voltage was zero. Where flux had a positive gradient, voltage was negative (V=-d(phi N)/dt). Last question was actually about double doppler shift (z=2u/v) because the atoms act as both a moving receiver and a moving source because they reflect, although I'm sure single doppler explanation and FDM will get the marks. With the photon wavelength I got 10^-12 m, you can just work out rest mass energy of one electron or positron and do E=hc/lambda. For the graph I got k = 2x10^14 in standard units and R=490 Ohms. Was tricky to get all units correct!

The raw mark in the paper (out of 60) is scaled up because either the mark scheme is too restrictive or the paper is too hard, so when you get your mark back and it says 80% UMS, you actually got about 60% raw. I got 100% UMS in PSA4 from 52/60!