"If a gap is much larger than the wavelength, there is no diffraction. If a gap is a few wavelengths wide, there is a little diffraction. If the gap is the same size as the wavelength, there is maximum diffraction." [from a revision guide]
What if a wavelength is much smaller than the gap? I know the answer to the question on set 2 states that there is diffraction but why is this the case? I said there wouldn't be any diffraction but I'm clearly wrong Any help would be much appreciated!
When my physics teacher showed us a simulation of waves passing through a large slit, it showed the waves largely passing straight through, however it also showed some diffraction on the edge of the wave front, where the wave had diffracted around the slit.
Note that the L in m / L is the total length rather than the length from X and Y (The other L is from X and Y). If you rearrange this equation, you should get the correct answer.
I did that, but I got it wrong, and when I checked the mark scheme, they muitlpied it by 4, which is what I don't get?
When were looking at the uncertainty do we take the smallest value it can measure e.g. with a ruler +-1mm or do we take HALF of the smallest measurable quantity i.e. +-0.5mm
I do not know the reason why you use 0.66 instead of 0.91, you just 'do'.
Imagine the whole string is vibrating and that points X and Y are just bits of the whole string. The WHOLE string has mass 3.1x10-3kg and the WHOLE string has length 0.91m. Therefore mass per unit length is m/l=3.4x10-3. This value does not change its like density kinda. Since the string is vibrating in the third harmonic the formula is 3x1/2l x sqrt(tension/mass per unit length) = 330. Now the BETWEEN points X and Y is 0.66m and between here they are vibrating at 330Hz. So finally use the value 0.66m in this formula with your previous mass per unit length i.e.
m/l = 3.4x10^-3 Therefore: 330 = 3/(2x0.66) x sqrt(tension/3.4x10-3) Now rearrange and you should get 71.7N
When we use micrometers, verniers and stopwatches do we take 2 x the uncertainty because of possible zero error or only once. Because i think you have to do that for a ruler but not sure about these