Ophelia_S2
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Homework Statement
a)What is the time t_B it will take for point B of the wavefront to encounter the vacuum/material interface?
Express your answer numerically to two decimal places in units of t_1 (the time it takes light to travel a distance d in a vacuum).
Homework Equations
n=c/v ; v = c/n
The Attempt at a Solution
uh..basically what i did for part a) i set sin(55 degree) = X/d where x is just a arbitary variable i used. Then let d*sin(55 degree) = x. here in the question it state it takes time t_1 to let speed of light travel a distance of d. so i let d = t_1, which will give me an answer of a value corrospond to t_1. However, after i plug in the number i am only getting 1.43(round off) and when i sub them into the system it says error. Most of time if the answer is close enough it will give me a feed back.. but i don't really know what i have done is wrong.. please someoen help me here..
Homework Statement
b)What is the new angle theta at which point C of the wavefront is propagating (relative to a line perpendicular to the vacuum/material interface)? Try to use the fact that you have a spherical wavefront propagating from t=0 at the point where C met the vacuum/material interface until time t_B when the wavefront at point B reached the interface.
Express your answer in terms of inverse trig functions and n (idex refreation i believe).
Homework Equations
d_c=(c*t_b)/n (this comes from part of the question i answer which is correct, and i believe
i suppose to sub the number d_c with those value to get my answer express for part b)
The Attempt at a Solution
btw, for part b) it's similar geometric problem and my attemps are the follow. set r = d_c, cos(theta) = r/a where a is the arbitary variable i use for hyp of the trig triangle. and a = r/cos(theta. Further more sin(35 degree) = d/a and a=d/sin(35 degree). i set both side equal and try to get an expression which work out to be d cos(theta) = r sin(35 degree). However when i sub the number from above equation in, i end up canceling everything and left with inverse cos ( sin 35 degree). can someone please help me out..this question are confusing, and i don't know how i going to approach it.
P.S Thanks to anyone who can give me some tips, mean while i think i will keep trying..the graph i attach to this question is a given graph that relevant for both question. sorry for any unclear part, this is my first time posting..