Light and Quantum Mechanics

Question 1

What is focal length of a lens ?

Answer 1

Focal length of a lens : the distance from the lens at which incident parallel light rays would intersect

Question 2

compared to visible light, x rays have what characteristics ?

Answer 2

X rays have have a higher frequency and energy per photon.

Question 3

How do you compare sound waves and light waves when moving from air to water ?

Answer 3

Sound waves SPEED up when moving from air into water whereas light waves slow down

Question 4

describe virtual image

Answer 4

It is located behind the reflecting surface of a mirror

Question 5

What provides best evidence of light behaving as a particle ?

Answer 5

Photoelectric effect

Question 6

Why does light bends toward the normal when it passes from air into water is:

Answer 6

because it slows down.

Question 7

What is the unit of Planck’s constant ?

Answer 7

kg x m^2/s

Question 8

What are the units for energy of photon

Answer 8

E= Joules= N x m = kg x m^2/s^2

Question 9

What is Wave Rule #1 regarding speed of a wave and frequency ?

Answer 9

The speed of a wave depends on the medium and the type of wave and does NOT change with a change in frequency.

Question 10

what is sin 60, 90 and 45 and 30

Answer 10

sin 30 : 1/2
sin 45: square root 2/2
sin 60 = square root 3/ 2
sin 90 = 1

Question 11

What is cos 30, 45, 60 , 90

Answer 11

cos 0 : 1
cos 30 : square root 3/2
cos 45: square root 2/2
cos 60 : 1/2
cos 90 : 0

Question 12

does water or air have greater index of refraction ?

Answer 12

WATER has a GREATER index of refraction that air

Question 13

What is the period of a spring system ?

Answer 13

period of a spring system: T = 2π√( m / k

Question 14

What is the Heisenberg uncertainty principle rule?

Answer 14

Heisenberg Uncertainty Principle: deltax x deltap greater than or equal to h/2 pi

the uncertainty of position x uncertainty of momentum is greater than nor equal to Planck’s constant /2 pi

Question 15

What is the relationship between speed of light and color change ?

Answer 15

Light will always travel at the SAME speed in a vacuum, regardless of color.

changing frequency, wavelength, or intensity will not change the speed of the light.

Question 16

compare the wavelengths of IR (infrared ) light, Visible light and Ultraviolet light

Answer 16

Infrared light has LONGER wavelength than visible light and that ultraviolet light has a shorter wavelength than visible light
(UV < Visible light< IR) for increasing wavelength
(if you have longer wavelength, have lower frequency)

Question 17

what type of lens is used for person with hyperopia ?

Answer 17

A hyperopic person is farsighted (cannot see things closely) . this is because the focal length is too long. This means that the image focuses behind the retina.
The type of lens that would be corrective for this person would be a CONVEX lens that CONVERGES light

Question 18

What is the correct lens to use for person with myopia ?

Answer 18

Myopia : nearsighted (cannot see things far away)
- focal length too short
-need Diverging lens
- image to be formed in front of the retina.
To“correct” the problem of the CONCAVE lens could be used

Question 19

What are characteristics of lasers ?

Answer 19

The light emitted by a laser is only of ONE color.
There is constructive interference between the waves emitted.

Question 20

describe relationship between wavelength and index of refraction

Answer 20

Longer the wavelength, the LOWER the index of refraction