LOVELY! Can i ask you for a favour and help me out on this question as well? I thought that it would halve, so be B but apparently I am wrong...
Hi, I did this question for practice and got the answer B, my physics teacher said that the mark scheme is wrong and the answer should actually be B. Other people in my class seemed to get B too. If you put a value in for D, say 100, into wavelength = ax/D, then it should point to the answer being B.
Hi, I did this question for practice and got the answer B, my physics teacher said that the mark scheme is wrong and the answer should actually be B. Other people in my class seemed to get B too. If you put a value in for D, say 100, into wavelength = ax/D, then it should point to the answer being B.
D is actually correct. You know that d sin x = nlambda
so d = nlambda / sin x
but d stays the same, so if the wavelength is increased, so must the angle to keep the same value of d.
increasing the angle increases the spacing.
I understand where you are coming from, but that equation is not for this question... tut tut tut ocr these days.
D is actually correct. You know that d sin x = nlambda
so d = nlambda / sin x
but d stays the same, so if the wavelength is increased, so must the angle to keep the same value of d.
increasing the angle increases the spacing.
I understand where you are coming from, but that equation is not for this question... tut tut tut ocr these days.
does that help?
Good luck to you tmrw too!
Haha now I'm confused, I had a look back at it and I put D in the first place, then the mark scheme said D and then my teacher said B! What equation is for this question then? and why are you talking about changing the angle? the angle doesnt change?
The value of D is the distance from sources to the screen, so this stays the same no matter what the angle?
Haha now I'm confused, I had a look back at it and I put D in the first place, then the mark scheme said D and then my teacher said B! What equation is for this question then? and why are you talking about changing the angle? the angle doesnt change?
The value of D is the distance from sources to the screen, so this stays the same no matter what the angle?
If all resistors are the same value, then the circuit forms a potential divider of (R + (R || R) = R + R/2.
The p.d. developed across resistor P is 2V/3 whilst the p.d. across the parallel combination is V/3
The current (I) flowing through P is also split between Q and R. (I splits into I/2 + I/2)
Power = VI = 12W
For resistor P, power = 2V/3 x I = 2/3 x 12W = 8W
For resistors Q and R, power = V/3 x I/2 = 1/6 x 12W = 2W each.
This is a really stupid question but I dont get how you worked out that P is 8W, the way I see it, it has I current whereas the other two have I/2? Is this not correct?
This is a really stupid question but I dont get how you worked out that P is 8W, the way I see it, it has I current whereas the other two have I/2? Is this not correct?
the ratio of resistance is 2 : 1 so one will have 8w and the other 4w
This is a really stupid question but I dont get how you worked out that P is 8W, the way I see it, it has I current whereas the other two have I/2? Is this not correct?
Yes that is part of it.
The other part is the p.d. developed across resistor P and the parallel resistors Q and R.
The p.d. across P is 2V/3 whilst the p.d. across Q and R is V/3.
Power = V x I = 12W
i.e. Power = 2VI/3 = 12 x 2/3 for resistor P
And
Power = V/3 x I/2 = VI/6 = 12/6 for each of the resistors Q and R.
The other part is the p.d. developed across resistor P and the parallel resistors Q and R.
The p.d. across P is 2V/3 whilst the p.d. across Q and R is V/3.
Power = V x I = 12W
i.e. Power = 2VI/3 = 12 x 2/3 for resistor P
And
Power = V/3 x I/2 = VI/6 = 12/6 for each of the resistors Q and R.
So essentially we are just finding the ratio of voltage in the resistors and using that? I managed t get the ration of 2/3 by assigning the same resistance to each and finding the total resistance. Then, worked out ratio of P and multiplied by 12 to get 8