AQA Physics Unit 1 PHYA1 20th May 2013

What about a neutron-neutrino interaction where the W- boson causes the neutrino to change into an electron? Or a proton - antineutrino interaction where the W+ boson causes the antineutrino to form a postiron?

What about a neutron-neutrino interaction where the W- boson causes the neutrino to change into an electron? Or a proton - antineutrino interaction where the W+ boson causes the antineutrino to form a postiron?

It all depends on the country. What people must realize is because the people who usually comment here roughly A/B boundary, they're going to say 'oh the exam was easy/moderately easy/fine'. So the grade boundaries here may be augmented slightly. I remember last year during my GCSEs, people here were saying, exam was easy, so 90 UMS will be 54/60. Surprisingly, 50/60 was 90 UMS. It all does truly depend.

My personal belief is that this paper will be 67-68/70 for 120 UMS.

The question asked what affect would decreasing the frequency so does that agree with what I wrote, I think that's what I was trying to say. If you imagine the threshold frequency of a metal was $6\times10^{14}$ for example, at this frequency the photons would only have energy to remove the electrons nearest to the surface as the photons absorbed by electrons further in would only cause them to collide with other particles within the metal and lose their KE.

Increasing the frequency then to $7\times10^{14}$ say, will mean that electrons further from the metal's surface will have energy sufficient to leave the metal so more electrons emitted when freq increased?

I looked at a quick interactive animation and increasing frequency meant higher photoelectric current.

Exactly, hadrons do interact through both the strong and weak interaction.. also a decay is just a type of interaction.

Why do you specifically need 114 may I ask?

this exam was so nice, wasn't too difficult

Did you calculate the power transformed by the battery?

yes

Interaction is always either w+ or w - in decay. Proton ---- turns into a neutron. So a hadron is responsible for weak since they decay through weak interaction. Not interact.

1) 20 p, 28 n, 18 e
2) + 3.2 x 10 ^-19 J
3) 3.99 x 10 ^ 6 C/kg
4) feynman stuff ( d quark, W+ Boson, positron, electron neutrino)
5) weak interaction
6) B
7) mass/charge/range etc
8) I did baryon number and electron lepton number conservation but there are mpre
9) big 6 marker, pretty easy
10) particle/ antiparticle: i did electron and positron and said charge was opposite

11) max and range of KE: photons energy dependant upon freq. as E= hf. Ekmax = hf - phi thereofore max KE exists. Range of ke's because more energy needed to remove deeper electrons etc.
12) prove 1.8eV (pretty easy)
13) what is threshold freq. : i got like 4.4 x 10 ^14 Hz
14)increasing frequency increases max KE of emitted electrons as by equation or by photon energy route, your choice
15) Double intensity doubles number of photons per second which doubles number of emitted electrons per second

16) peak to peak = 128V
17) peak = 64V
18) Vrms = 45 V
19) freq. = 100 Hz
20) horizontal line at 45V
21) time base: 2ms/div y sensitivity: 16V/div dunno about 3rd mark

22) 4.2 x 2.5 = 6.3V
23) 12- 6.3 = 5.7V
24) 5.7 / 2 = 2.85A
25) 4.2 - 2.85 = 1.35 A
26) R = 5.7 / 1.35 = 4.2
27) I said total R is 1.4 but if it incuded internal resistance then it was 2.9 ohms
28)think something after but forgot sorry

29) current = 6/ (50 + 35 + 5 ) x 1000 = 6.7 x 10 ^-5 A
30) V = 0.33V
31) increas intensity decreases toatl resistance which increases total current thereofre voltemeter value is greater (alternatives possible)
32) 30000 ohms