Particles and Waves: 6 - Refraction Flashcards
What is the definition of the absolute refractive index of a medium?
The ratio of the speed of light in a vacuum to the speed of light in the medium.
What is a refractive index?
A measure of the effect a medium has on light.
What does a greater refractive index make happen?
A greater change in speed and direction.
When does the refractive index of a medium increase?
The refractive index of a medium increases as the frequency of incident radiation increases.
What is the refractive index always a value greater than or equal to?
1
What is the refractive index of a vacuum?
1
What is the refractive index of air?
1.000277 or 1
What is the equation for the refractive index?
n2/n1 = sinθ1/sinθ2
What is n2/n1 = sinθ1/sinθ2 equal to?
n2/n1 = sinθ1/sinθ2 = v1/v2 = λ1/ λ2
Describe an experiment for the refractive index of a medium?
Aim:
To find the relationship between the incident angle and angle of refraction for light travelling from air into perspex.
Apparatus:
Ray box and single slit, 12v power supply, semi-circular perspex block, sheet of white paper and protractor.
Instructions:
Place the block of the white paper and trace around its outline. Draw in the normal at the midpoint.
With incident angle θ1 = 10°, measure the angle θ2, the refracted angle in the perspex.
Repeat for the other values of incident angle.
plot a graph of sinθ1 against sinθ2.
Conclusion:
Sinθ1 is directly proportional to sinθ2 as it is a straight line through the origin
What is the critical angle?
The angle of incidence which produces an angle of
refraction of 90°.
When does total internal reflection occur?
When the angle of incidence is greater than the critical angle.
What is the equation for a critical angle?
Sinθc = 1/n
