7 - Introduction to Prisms Flashcards
What is the definition of prism? 3
A prism consists of two angled refracting surfaces. The simplest form of a prism is two flat surfaces that come together at an angle at the top. The point is called the apex of the prism; the wider bottom of the prism is called the base.
What do prisms do?
Cause light to change directions without changing the vergence (Power)
Where is the light bent?
Towards the base
Where are images displaced?
Towards the apex
The wider the base of the prism, the greater the ability to divert light. T/F
TRUE
What measurement is the apical angle equal to? see diagram
When it hits a flat surface the apical angle is equal to the angle which it strikes the second surface.
What is the angle of deviation?
The amount the light has deviated from its original path.
Where do we measure the angle of deviation from?
Normal to Original line of path.
(See diagram)
When does light bend away from the Normal?
When passing from a dense medium to a rarer medium
When does light bend towards the normal?
When passing from a rare medium to a denser medium
How do we know when it is a thin prism?
When the apical angle is under 10 degrees
When do we use the formula d=a(n-1)?
When apical angle is under 10 degrees
When do use snells law and angle of deviation?
When the apical angle is over 10 degrees
When do we use the formula d=a/2 ?
When apical angle is under 10 + the refractive index is under 1.5 plastic
What is the refractive index’s of these materials?
Crown Glass
CR-39
Trivex
Polycarbonate
Air
Water
Crown Glass = 1.523
CR-39 = 1.498
Trivex = 1.532
Polycarbonate = 1.586
Air = 1.00
Water = 1.33
