# Higher Physics 2018-19Watch

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1 week ago
#61
The colour observed at Y is red but I'm not sure how you know this. Would be great if someone could explain how this diagram shows that Y is red.
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1 week ago
#62
(Original post by Lil Impulse)
The colour observed at Y is red but I'm not sure how you know this. Would be great if someone could explain how this diagram shows that Y is red.
Maybe coz like red has got the longest wavelength so because the line pointing at the specta is at the edges (of the spectra) it corresponds to the red wavelength. Like if the line was in the middle by ROYGBIV it would be like violet ?
Last edited by XZS; 1 week ago
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1 week ago
#63
Sorry to correct you here. But the part with the 3 resistors is a parallel branch. Voltage is the same across all components in a parallel, whether it be an entire circuit or a branch. So D is therefore correct.
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1 week ago
#64
It’s only memory you need for this question. Blue light refracts to a greater degree than red light, because it has higher frequency and refractive index increases with frequency. Red refracts less and will therefore always appear at the top of a refraction spectrum. It is the opposite for diffraction, so blue always appears first and red last.
(Original post by Lil Impulse)
The colour observed at Y is red but I'm not sure how you know this. Would be great if someone could explain how this diagram shows that Y is red.
1
1 week ago
#65
Ah yeah haha thanks for that, sorry, my bad. I got the correct values but I just misread the table so I said B instead of D for some reason? Anyway thanks for pointing it out
(Original post by Mortifiedpenguin)
Sorry to correct you here. But the part with the 3 resistors is a parallel branch. Voltage is the same across all components in a parallel, whether it be an entire circuit or a branch. So D is therefore correct.
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1 week ago
#66
Lol my mistake! I never actually read your method, if I had I would have noticed you were approaching it right and simply stated the wrong answer.
(Original post by sbneelu)
Ah yeah haha thanks for that, sorry, my bad. I got the correct values but I just misread the table so I said B instead of D for some reason? Anyway thanks for pointing it out
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1 week ago
#67
(Original post by XZS)
Maybe coz like red has got the longest wavelength so because the line pointing at the specta is at the edges (of the spectra) it corresponds to the red wavelength. Like if the line was in the middle by ROYGBIV it would be like violet ?
(Original post by Mortifiedpenguin)
It’s only memory you need for this question. Blue light refracts to a greater degree than red light, because it has higher frequency and refractive index increases with frequency. Red refracts less and will therefore always appear at the top of a refraction spectrum. It is the opposite for diffraction, so blue always appears first and red last.
Thanks i think i get how you do it. I understood the refracting part but the diffraction part just confused me
Last edited by Lil Impulse; 1 week ago
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1 week ago
#68
Nah it's fine haha dw, it's my fault
(Original post by Mortifiedpenguin)
Lol my mistake! I never actually read your method, if I had I would have noticed you were approaching it right and simply stated the wrong answer.
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1 week ago
#69
(Original post by Lil Impulse)
The colour observed at Y is red but I'm not sure how you know this. Would be great if someone could explain how this diagram shows that Y is red.
Just so there is no confusion here, refraction say through a prism will cause blue light to (bend) more than red light when viewed on the screen due to dispersion, this is Newtons experiment.
For interference by diffraction through a grating will cause red light projected on screen further from the central axis than blue (the other way about than refraction), because path difference for red light larger than blue; for m'th order.
Last edited by tomctutor; 1 week ago
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1 week ago
#70
(Original post by tomctutor)
Just so there is no confusion here, refraction say through a prism will cause blue light to (bend) more than red light when viewed on the screen due to dispersion, this is Newtons experiment.
For interference by diffraction through a grating will cause red light projected on screen further from the central axis than blue (the other way about than refraction), because path difference for red light larger than blue; for m'th order.
Cheers i completely forgot about path difference when thinking about wavelengths and interference but that makes sense
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1 week ago
#71
Hi, can anyone help me with Q25 on the 1992 Paper Multiple choice? I have no clue. ThanksLink to paper - http://mrmackenzie.co.uk/wp-content/...92_HigherI.pdf
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1 week ago
#72
Hi, I think the answer would be A. This is because when light goes from glass to air it is going into a less dense medium this means that it will bend away from the normal. Then when it renters the glass it will bend back towards the normal. Then when going out into the air again it will bend away. This leaves A as the only option. Hope this makes sense
(Original post by SamSpudd)
Hi, can anyone help me with Q25 on the 1992 Paper Multiple choice? I have no clue. ThanksLink to paper - http://mrmackenzie.co.uk/wp-content/...92_HigherI.pdf
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1 week ago
#73
Hi, I think the answer would be A. This is because when light goes from glass to air it is going into a less dense medium this means that it will bend away from the normal. Then when it renters the glass it will bend back towards the normal. Then when going out into the air again it will bend away. This leaves A as the only option. Hope this makes sense
Brilliant, answer is indeed A, thanks for the explanation too.
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1 week ago
#74
No problem

(Original post by SamSpudd)
Brilliant, answer is indeed A, thanks for the explanation too.
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1 week ago
#75
2016 Multiple choice Question 13. Am I right in saying you use the dsin(Theta) =m(Lambda).

If so how do you determine what m is? I thought it was how many first-order maximums there are but apparently not.
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1 week ago
#76
You are correct that you have to use that equation. But you need to find d not m. M=1 theta=18 and lambda=663x10-9
(Original post by AstralDwarf)
2016 Multiple choice Question 13. Am I right in saying you use the dsin(Theta) =m(Lambda).

If so how do you determine what m is? I thought it was how many first-order maximums there are but apparently not.
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1 week ago
#77
Ohhhh I was using the wrong angle cheers.
You are correct that you have to use that equation. But you need to find d not m. M=1 theta=18 and lambda=663x10-9
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1 week ago
#78
No problem
(Original post by AstralDwarf)
Ohhhh I was using the wrong angle cheers.
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1 week ago
#79
does anyone know how to do this question attached below? Thanks
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1 week ago
#80
Which paper is that? You need more information to solve that (either the unbalanced force or a way of finding the unbalanced force), can you send the rest of the question please?
does anyone know how to do this question attached below? Thanks
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