Qualification > Sciences
Edexcel PHYSICS Doubts
Romeesa-Chan:
--- Quote from: Ari Ben Canaan on June 05, 2011, 05:42:25 am ---Q1
% Uncertainty = uncertainty of instrument / actual measurement.
Each foil is 15 micrometres thick. When you decide to measure the thickness of the foil will you measure the thickness of only one foil or several ?
You would do it for several so as to gain an average and eliminate random uncertainties.
If I were you I would measure the thickness of 8 sheets or more. That's where the eight comes from.
Q2
In a roundabout fashion they are asking you to calculate the percentage uncertainty whilst showing workings.
--- End quote ---
For Q1. Why 8? It can be any number, right? Like. . . 10/12?
Can you please help with Q. 3 & 4?
Romeesa-Chan:
Momentum conservation using a linear air track.
Describe means of stopping the riders gently at the far end of the track.
deadlyelder:
How to calclulate the Critical Angle? If anyone has example please post it for clarification I am confused.
Thanx
The Golden Girl =D:
--- Quote from: deadlyelder on June 05, 2011, 02:24:16 pm ---How to calclulate the Critical Angle? If anyone has example please post it for clarification I am confused.
Thanx
--- End quote ---
If a ray of light is moving from Denser *glass* to rarer *air* then we use this formula
sin c= na / na
so Critical angle equals to sin inverse the refractive index of Air over the refractive index of Glass
i.e.
c = sin-1 [ na/ na ]
Example
c = sin-1 [ 1.00 / 1.5 ]
= 42
I believe it's 42 :)
I hope you got it :D
MasterMath:
I just want to make sure of something correct me if im wrong
In the photo electric effect .. when your shinning radiation on a metal's surface. If you increase the intensity you increase the number of electrons getting knocked out, but if you increase the frequency your just increasing the K.E the electrons gain right? So frequency has no effect on the current(number of electrons emitted)?
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