Guys, i have missed a fair bit of school this term (lucky year 11 ) and have have very little clue to do with anything about refractive index/snell's law e.g. I have read thoroughly through out my text book and am finaly starting to understand bits and pieces, however i dont have any practise questions in order to implement and test my new knowledge lol..
Please if anyone out there has any questions(excercises) with solutions regarding this, please helpp out
Flick your cursor over the spoilers only if you finish calculating your answer and want to see if it is correct or not.
Don't cheat please.
Where necessary in this set, use absolute refractive index (n) of air = 1.00
1) A ray of light with an angle of incidence of 35.0o enters a block of polystyrene. The angle of refraction is 21.0o.
(a) If the direction of the incident ray is altered,
what is the ratio of the sine of the new angle of incidence to the sine of the new angle of refraction ?
Answer:
1.60
(b) What is the relative refractive index for light passing from air to polystyrene ?
Answer:
1.60
(c) What would be the relative refractive index for light passing out of the polystyrene into air ?
Answer:
0.625
2) A ray of light enters the side wall of a fish tank.
The angle of refraction is 47o as the light passes from the glass into the water.
If the relative refractive index for light passing from glass into water is 0.88, what is the angle of incidence ?
Answer:
40o
3) A ray of light in water meets a flat-sided block of perspex with an angle of incidence of 55.0o.
The angle of refraction in the perspex is 47.0o.
If the absolute refractive index (more commonly known as the refractive index) of water is 1.33,
determine the refractive index of perspex.
Answer:
1.49
4) A ray of light is incident on a plane glass surface at an angle of 30.0o.
Given that the refractive index of the glass is 1.50,
calculate the angle of refraction and the angle of deviation.
Answer:
19.5o; 10.5o
5) A ray of light makes an angle of incidence of 42.8o at the boundary of glycerine and flint glass.
If the absolute indices (indexes) of these materials are 1.47 and 1.72 respectively, through what angle is the ray deviated ?
Answer:
7.3o
6) A narrow parallel beam of light strikes a glass block so that it makes an angle of 60.0o with the normal to the glass surface.
Part of the beam is reflected and part is refracted, the angle between the reflected and refracted portions being 90.0o.
Find by calculation the refractive index of the glass.
Answer:
1.73
7) What is the speed of light in glass given that the speed in air is 3.0 x 108 m.s-1 ?
Use the following data:
Refractive index (n) of glass: 1.50
Answer:
vg = 2.0 x 108 m.s-1
Where vg is the velocity of light in glass
8) What is the critical angle for light travelling from water into air ?
Use the following data:
Refractive index (n) of water: 1.33
Answer:
ic = 48.8o
Where ic is the critical angle of incidence
9) Glass has a refractive index of 1.5.
Calculate the critical angle for glass.
sorry to be such a pain man but i just cant seem to get the right answers :S
the only one ive gotten is #2.. im sure im doing thigs properly, but this oviously
isnt reflecting on my answers lol:S
e.g.
i have applied this principal to every question and still no luck :S
sini n(2)
----- = ------
sin r n (1)
please can some one do examples 1,3,4 & 8 with just simple steps of working out with a small description of why/how?
sorry if i appear or seem annoying lol but i really wanna get the hang of this stuff, and its rather hard when your sitting at home trying to learn it all by ur self
sorry to be such a pain man but i just cant seem to get the right answers :S
the only one ive gotten is #2.. im sure im doing thigs properly, but this oviously
isnt reflecting on my answers lol:S
e.g.
i have applied this principal to every question and still no luck :S
sini n(2)
----- = ------
sin r n (1)
please can some one do examples 1,3,4 & 8 with just simple steps of working out with a small description of why/how?
sorry if i appear or seem annoying lol but i really wanna get the hang of this stuff, and its rather hard when your sitting at home trying to learn it all by ur self
1)
a) The question does NOT mention anything about refractive index, rather the use of RATIOS.
You know
sin i / sin r = n2 / n1
Don't worry about n2 / n1 for now.
Fill in the data
sin i / sin r = sin 35o / sin 21o = 1.6
b)
Use the result from the previous answer
Make n2 the subject because that's the refractive index of polystyrene.
1.6 = n2 / n1
Let n1 = 1
We assume n1 = 1 because we find the refractive index of polystyrene RELATIVE to air.
c)
Use the result from the previous answer
Make n2 the subject because that's the refractive index of polystyrene.
1.6 = n2 / n1
n1 = n2 / 1.6
Let n2 = 1
We assume n2 = 1 because we find the refractive index of air RELATIVE to polystyrene.
Air is now in our interest (or subject) instead of polystyrene.
My computer suffers from severe instabilities so I can't help you all in one go.
ok i think i know what the problem has been this whole time lol... my calculator
is teh f***eDDDD!!! i entered the exact same information on my calculator and
my m8s 1... he got all correct answers, i got some random way off crap :S
and the thing is, i now know whats responsible for me failing my trig test haha
life suxx lol... it seems that my calculator is teh f***ed every time i use SIN, COS
or TAN functions lol i get wack results..
thanks for the explanations though man, been really helpful
) and have have very little clue to do with anything about refractive index/snell's law e.g. I have read thoroughly through out my text book and am finaly starting to understand bits and pieces, however i dont have any practise questions in order to implement and test my new knowledge lol..