OCR Physics A G482, Electrons, Waves and Photons, 25th May 2012

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It was a "suggest" question I guess :confused:

I'd laugh if someone actually knew about single slit interference and answered that question with it xD

Lol i wrote about single slit interference without knowing about it xD cos it wasnt monochromatic light hence it was light with different wavelenghts which were bound to interfere with each other :s-smilie:

Reply 581

sdgvrgverg

how did you work out you get 3V? It seems familiar but I'm not sure if I did the right thing

Reply 582

Brister

Original post by imsoofukinbored

WTH are we supposed to write about the single slit??
i cudnt answer the question so i just made up some shiz :tongue:

this is what i wrote :
-bright spot in the middle
-other spots' intensity is very very low
-spots edges blurred
probz lose all the marks but does anyone know the correct answer ?

Sure thing. It isn't intuitive, but you do actually get interference! This is because you can consider that there are loads of point sources across the slit. What you get is a very bright central fringe followed by the familiar pattern of dark and bright fringes, although the other fringes are much dimmer than the central one.

Reply 583

SamXi

Original post by sdgvrgverg

how did you work out you get 3V? It seems familiar but I'm not sure if I did the right thing

We worked out the fixed resistor was 2kohms and then read off the graph the resistance of the LDR was 1kohm so then its a ratio

(1000x9)/3000

Reply 584

danielpickwick

For the one where you covered up one slit, you'd get one continuous band of light because the light goes through the slit and is diffracted, and the it doesn't go through the other slit because it's covered up, and you'd assume there's no other source of coherent (yellow?) light, so there would be no interference.

That's what I thought anyway

Reply 585

sdgvrgverg

oh I think I had the fixed resistor as being 1904 rather than 2000. (1904 is roughly 2kohms)
I did 4/(2.1*10^-3) rather than using 2mA. hopefully will get ecf

Reply 586

Awesomesauce

Original post by eddie90

all you had to do to show it was 2kohms was do 9v - the 5vs from the led (or whatever it was) then divide the 4v by the current which was 2x10^-3 :smile:

Yes! I did this through number bashing!

Reply 587

Brister

Original post by Joseppea

It was a "suggest" question I guess :confused:

I'd laugh if someone actually knew about single slit interference and answered that question with it xD

You can actually find this in the OCR textbook, although it isn't in one of the spreads. They snuck it in as one of the questions. I'm just glad that I saw it!

Reply 588

Pheylan

Original post by benji15000

I talked to my teacher, she said single slit interference occurs, which is a completely different subject which is not on the syllabus. So she is writing in to get the questions removed.

Original post by Joseppea

It was a "suggest" question I guess :confused:

I'd laugh if someone actually knew about single slit interference and answered that question with it xD

Ha! I wrote that it would interfere with itself. Thank **** for CGP.

Reply 589

imsoofukinbored

Original post by Brister

ohhh thanks :smile:

do you think id get some marks for my answer?

Reply 590

conzag123

Original post by benji15000

I talked to my teacher, she said single slit interference occurs, which is a completely different subject which is not on the syllabus. So she is writing in to get the questions removed.

We did this off the wall as our techers said there's a chance it could come up! GOD BLESS THEM! (though they are the reason I'm dropping physics next year...)

Reply 591

Brister

Original post by imsoofukinbored

ohhh thanks :smile:

do you think id get some marks for my answer?

You mentioned the bright spot in the middle and that the other spots became increasingly dim, so yes - and I should hope that you do!

Reply 592

conzag123

Original post by Awesomesauce

I think in this case they only expect us to talk about one bright band, as the single slit diffraction effect is on other side of the huge middle band, which in the question, it states that the picture shows the centre fringes. I am doubtful they expect many people to understand single slit diffraction.

I am hopeful i got 80+ aswell. I am just worried that I put most of my answers in standard form with the same number of SF they used in the question, eg 21600 J = 2.2x10^4 J

dw i did the standard form thing too with the SF and im sure it's fine as it's what our teacher explicity insists is "proper" physics :tongue:

Reply 593

conzag123

Original post by -illmatic-

lol i wrote about single slit interference without knowing about it xd cos it wasnt monochromatic light hence it was light with different wavelenghts which were bound to interfere with each other :s

booom ! :d

Reply 594

The medjai

Wha....A light wave with one slit interferes with itself?

Reply 595

imsoofukinbored

Original post by Brister

You mentioned the bright spot in the middle and that the other spots became increasingly dim, so yes - and I should hope that you do!

thank you;p thats good haha what a damn lucky guess :biggrin:

was hoping for an A to make up my pathetic excuse of a mechanics paper

Reply 596

taunt

Original post by ShahzaibMuneeb

Guys, for the heater question, they were referring to "strips", last time I checked strips weren't circular :P Just to clear that up you had to multiply the thickness by the width :smile:

WHAT!!!!

oh ****!!! :mad:

I did nothing with the width!!!

I just divided the thickness (diameter), to get radius!!!
then r^2, then I did pie*r^2 to get cross-sectional area!!!!!

dayum, I so ****ed that paper!!!!!!!