# AQA Physics B Unit 5 - How did you do?

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Thread starter 15 years ago
#21
(Original post by Wings)
approx. 2.5m it has to be half the wavelength of original wave since it starts 180 degrees outa phase
I got 2.3.

Worked out Lambda by using v = fLambda

Then divided it by 2, is that what you did?
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15 years ago
#22
yeh thats correct
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Thread starter 15 years ago
#23
For the question where it had the electron as a standing wave, when it told you to calculate the Potential energy, did you use the formula? I thought you needed to use the formula but they didnt give you the charges of an electron/proton so I just went back and found the charge of an electron...

Also, for the graph question, did you find the numbers of squares x value of one square, times the mass of the satellite?
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15 years ago
#24
Btw wen u said it will not exceed 1.5% you were rite.. so relax.

To work out intensity u had to say

Intensity= Activity in one sec X energy per molecule

The activity is found by saying A=N lambda (u know lambda since u had to work it out)
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Thread starter 15 years ago
#25
(Original post by Wings)
Btw wen u said it will not exceed 1.5% you were rite.. so relax.

To work out intensity u had to say

Intensity= Activity in one sec X energy per molecule

The activity is found by saying A=N lambda (u know lambda since u had to work it out)
Did you get 1.5% as well?
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15 years ago
#26
Yeh i got 1.5%

The charge question is the only one i cudnt do. didnt give me charge ??

And yes u just had to times area by mass of satellite. However, i missed the estimate bit and worked it out with the formulae. The mass of sun cud easily be worked out by taking a point on the graph and saying g= Gm/r^2 where m is mass of earth.

Eith way is correct.. I just did it the much longer way..o well
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Thread starter 15 years ago
#27
(Original post by Wings)
Yeh i got 1.5%

The charge question is the only one i cudnt do. didnt give me charge ??

And yes u just had to times area by mass of satellite. However, i missed the estimate bit and worked it out with the formulae. The mass of sun cud easily be worked out by taking a point on the graph and saying g= Gm/r^2 where m is mass of earth.

Eith way is correct.. I just did it the much longer way..o well
What charge question are we talking about here?
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15 years ago
#28
work out potential energy of electron.. some reason that got me???

Pe= Qq/ (4 pi E r)

Where the heck was Q or q (ie charges of particles.. or were i to simply assume they were +1 and -1 ???)
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Thread starter 15 years ago
#29
(Original post by Wings)
work out potential energy of electron.. some reason that got me???

Pe= Qq/ (4 pi E r)

Where the heck was Q or q (ie charges of particles.. or were i to simply assume they were +1 and -1 ???)
Yeh thats the question Im on about

I went back, found the charge of an electron(1.6x10^-19) and seen as the chrage on a proton is equal but opposite, its just (1.6x10^-19)^2

Thats how I did it, but like you say, they didnt give us charges so maybe they were expecting a different method?
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15 years ago
#30
Well its not TOO many marks anyway so shudnt matter too much.. especially if around 58/100 wud be an A.

So relax.. at least all the physics is OVER!!!

lol

What uni u hoping to goto m8?
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Thread starter 15 years ago
#31
(Original post by Wings)
Well its not TOO many marks anyway so shudnt matter too much.. especially if around 58/100 wud be an A.

So relax.. at least all the physics is OVER!!!

lol

What uni u hoping to goto m8?
York, you?
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15 years ago
#32
Hopefully UCL : )

What u studying?
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Thread starter 15 years ago
#33
(Original post by Wings)
Hopefully UCL : )

What u studying?
Physics
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Thread starter 15 years ago
#34
Also, I thought it was quite strange having 2 questions saying stuff like:

'Show that the kinetic energy of the electron can be represented by this equation 3 marks for rearranging equations..I have to add I though they were pretty tricky equations as well :|
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15 years ago
#35
ive did so terrible, need an A but its looking very unlikely! Did ne 1 get 1m fot the length for da plate, plz say yes cuz its bout da only one i cud do
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Thread starter 15 years ago
#36
(Original post by Marie123)
ive did so terrible, need an A but its looking very unlikely! Did ne 1 get 1m fot the length for da plate, plz say yes cuz its bout da only one i cud do
Yes I got 1m, I thought I did it wrong though.

I did Ft = mv

found t, multiplied by 0.80
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15 years ago
#37
Are you talking bout how the long the plate has to be in order to catch the dust particle??
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15 years ago
#38
(Original post by imasillynarb)
York, you?
what's your offer and what are you expecting?
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Thread starter 15 years ago
#39
(Original post by Wings)
Are you talking bout how the long the plate has to be in order to catch the dust particle??
Yeh
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Thread starter 15 years ago
#40
(Original post by elpaw)
what's your offer and what are you expecting?
BBB, god knows what Im gonna get though. I was hoping for AAB, but it seems increasingly unlikely, and depending on how chemistry goes tomorrow Itll probably be BBC Why?
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