Edexcel Physics Unit 3 9th May

Prefix are considered part of a unit so microm^-1 is 1/microm, which makes sense.

Its a wave number, we studied this in Chem. I might have got confused

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1/micro is mega.

I didn't study it anywhere, but it makes mathematical sense really

I'll demonstrate this with an example.

The first wavelength was 630 nanometres I believe, and the inverse given was 1.59.

Let's make this simple and convert it all to SI units first.

630 nanometres is $630 \times 10^{-9} \mathrm{ \ m} = 6.3 \times 10^{-7} \mathrm{ \ m}$.

Inverse this, and we get 1590000 m^-1 to 3 s.f.

Which is 1.59 Mega m^-1!

Wrong!
How did you state it in the answer?
Mm^-1?
That's wrong ( but they might accept!)
Real way is to put as micro+meter+^-1 (no spaces in between)
Don't get me wrong!
I know that the correct answer is 10^6 * m^-1 but you can't simply replace 10^6 with M.
What you can do is replace it with (micro symbol) .it will be treated as a part of the unit.
HERE IS SOME PROOF:
6.2.3 Inseparability of prefix and unit The grouping formed by a prefix symbol attached to a unit symbol constitutes a new inseparable symbol (forming a multiple or submultiple of the unit concerned) which can be raised to a positive or negative power and which can be combined with other unit symbols to form compound unit symbols. Examples: 2.3 cm3 = 2.3 (cm)3 = 2.3 (10−2 m)3 = 2.3 × 10−6 m3 1 cm−1 = 1 (cm)−1 = 1 (10−2 m)−1 = 102 m−1 5000 µs−1 = 5000 (µs)−1 = 5000 (10−6 s)−1 = 5000 × 106 s−1 = 5 × 109 s−1 1 V/cm = (1 V)/(10−2 m) = 102 V/m Prefix names are also inseparable from the unit names to which they are attached. Thus, for example, millimeter, micropascal, and meganewton are single words

Prefix are considered part of a unit so microm^-1 is 1/microm, which makes sense.

Its a wave number, we studied this in Chem. I might have got confused

Posted from TSR Mobile

Prefix are considered part of a unit so microm^-1 is 1/microm, which makes sense.

Its a wave number, we studied this in Chem. I might have got confused

Posted from TSR Mobile

Unofficial mark scheme:
1)B 2) D 3)C 4)B 5) C

6) Disscus Advantages and DIs advantages about uncertainty

7)Experiment for Spring constant

8) m = hc/e c = speed of light, e = electron charge

8 part c) Graph ,part d) find plancks constant ,part e)Suggest difference between real constant and your given constant i calculated 5.54x10 -34



btw the way i finished 20mins early

How did you get 5.54x10^-34?
What did you get for gradient. I got one hence I got h to be 5.3x10^-28

My graph went through origin, cutting 3 points but I used a scale of 1 every 10 squares, so my gradient was 0.68

Got planks constant as 3.x * 10^28. Didn't multiply it by 10^6 either...

How much do you reckon I'll get for graph + plank constant out of 11?

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i got h = 4.1x10^-34
almost everyone in class got that as well...

My graph went through origin, cutting 3 points but I used a scale of 1 every 10 squares, so my gradient was 0.68

Got planks constant as 3.x * 10^28. Didn't multiply it by 10^6 either...

How much do you reckon I'll get for graph + plank constant out of 11?

Posted from TSR Mobile

10²⁸ or 10^-28? If it's the former, then that's way off.

Hmm, why would the scale change your gradient? It shouldn't make a difference what scale you'd use.

If you plotted the points correctly and did everything else right, it's probably an issue with your best fit line. I'd say 8 or 9 out of 11, if you did everything else right.

Yeah, I got 4.00 x 10^-34... I'm not too sure how some people on here got more than 5

I got 3.63! Which is much closer to your value than the others at my school. Most of them got 5!

I suppose its because they didn't cut through the origin, so their gradient was larger, leading to a higher planck constant.

Posted from TSR Mobile

Hmm, why would the scale change your gradient? It shouldn't make a difference what scale you'd use.

i got 100 Hz for the mcq
how is the answer 250 Hz? ;/

i got some what 5.4*10^-34 it should be correct ans because it close to the original value also i tripled checked cause i finished the exam 15 earlier.