Light and Optics

Question 1

Speed of Light

Answer 1

• c = λf
  
  • c = 2.98 x 10⁸ m/s

Question 2

Plane Polarized Light

Answer 2

• I = I₀cos²(θ)

Question 3

Law of Reflection

Answer 3

• The law of reflection states that the angle an incident light ray makes with a surface is equal to the angle that the reflected light ray makes with the surface; θ_i = θ_r

Question 4

Index of Refraction

Answer 4

• The index of refraction, n, is the ration of the speed c of an electromagnetic wave in a vacuum to the speed of that wave in a given medium
• n = c/v = v_vacuum/v_medium
• The larger the value n, the slower the wave travels in the new medium

Question 5

Snell’s Law

Answer 5

• Relates index of refraction and angle of refraction
• n₁sin(θ₁) = n₂sin(θ₂)
  
  • If n₂ > n₁, the incident light ray will bend towards the normal
  • If the opposite is true, the incident light ray will bend away from the normal

Question 6

Total Internal Reflection

Answer 6

• At some critical angle θ_c, an incident light ray will refract at exactly 90^o to the normal, resulting light running across the interface of the two media
• Any angle greater than the critical angle will result in total internal reflection
• The greater the ratio of n₁:n₂, the smaller the critical angle

Question 7

Dispersion

Answer 7

• EM waves of different wavelenghts travel at differnt speeds through media
• Wavelength is inversely proportional to the degree of bending
  
  • Smaller wavelenght, greater bending
• EM waves that bend more have a greater index of refraction, n
  
  • Greater n means slower wave

Question 8

Real and Virtual Images

Answer 8

• A real image can be projected onto a screen
• A virtual image cannot be projected onto a surface

Question 9

Thin Lens Equation

Answer 9

• 1/f = 1/s + 1/s’
  
  • f = focal length
    
    • Positive for converging and negative for diverging
  • s = object distance
    
    • If the object is left of the lens, the value is positive; if the object is right of the lens, the value is negative
  • s’ = image distance
    
    • Real images will give a positive value; virtual images will give a negative value

Question 10

Mirrors

Answer 10

• Plane mirror
  
  • ALWAYS upright, virtual, and same size
• Convex mirror
  
  • ALWAYS upright, virtual, and smaller
• Concave mirror
  
  • Image depends on focal length
• f = R/2

Question 11

Lenses

Answer 11

• Converging lens
  
  • f is positive
• Diverging lens
  
  • f is negative

Question 12

Magnification

Answer 12

• m = h’/h = s’/s

Question 13

Space Between Two Adjacent Maxima

Answer 13

• y = λL/d
  
  • L is length from the slits to the screen
  • d is the distance between the two slits