You can use your results from a as known values to solve b. I recommend using a

Question

You can use your results from a as known values to solve b. I recommend using a separate checklist for the two parts. You’ve poured a 2.0-cm-thick layer of water (n=1.33) on top of a 3.5-cm-thick layer of polystyrene plastic (n=1.59). A ray of light enters your construction at an angle of 30 degrees above the horizontal, refracts, reflects off the bottom surface of the polystyrene, and then works its way back to the surface.

a. How far has the light traveled when it exits your stack of materials?

b. How long (in ns) does it take the light to pass through the stack of material?

Explanation / Answer

angle of incidence i1 = 90 - 30 = 60

from snell law of refration

nair*sini = nwater*sinr1

1*sin60 = 1.33*sinr1

r1 = 40.6 degrees

distance travelled in water l1 = t1/cosr1 = 2/cos40.6 = 2.63 cm

from water to polystyrene

angle of incidense i2 = 40.6

angle of refractaction r2 =

nwater*sini2 = npoly*sinr2

1.33*sin40.6 = 1.59*sinr2

r2 = 33

distance travelled in polystyrene l2 = t2/cosr2 = 3.5/cos33 = 4.17 cm

distance traveleed d = l1 + l2 = 6.8 cm   <<<-------answer

(b)

speed of light in water v1 = c/n1

speed of light in poly v2 = c/n2

time taken t = t1/v1 + t2/v2

t = n1*t1/c + n2*t2/c

t = (n1*t1 + n2*t2)/C

t = ((1.33*0.0263) + (1.59*0.0417))/(3*10^8)

t = 0.337 ns <<<<-----answer

Related Questions

Navigate

• Browse (All)
• Browse Y
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.