Unit 1.1 Physics of Light

Question 1

What are light and sound composed of?

Answer 1

Waves

Question 2

What is a wave?

Answer 2

a type of internal motion of a medium, where a disturbance propagates in space and time, and the displaced portion returns to equilibrium.

Question 3

What are the different types of waves?

Answer 3

• transverse waves
• longitudinal waves

Question 4

What are transverse waves?

Answer 4

the displacement of particles is perpendicular to the direction of wave propagation. An example is the vibrations of stringed instruments.

Question 5

What are longitudinal waves?

Answer 5

the displacement of particles is parallel to the direction of wave propagation. An example are sound waves, where air molecules oscillate back and forth, and wind instruments.

Question 6

What are sound waves?

Answer 6

they involve the longitudinal oscillations of air molecules. The sound vibrations in a long, narrow tube (flute) propagate in one direction

Question 7

What happens to a sound wave in the open air?

Answer 7

the sound wave propagates radially in all directions

Question 8

What are light waves?

Answer 8

they involve transverse oscillations in electric and magnetic fields

Question 9

How do light waves propagate?

Answer 9

Light waves propagate as disturbances in space and time, moving in a direction perpendicular to the oscillations of the electric and magnetic fields.

Question 10

What is natural frequency?

Answer 10

Natural frequency is the specific frequency at which an object vibrates most readily. It is influenced by factors such as tension, length, and mass.

Question 11

How does the natural frequency change for vibrating stings?

Answer 11

the natural frequency increases with the tension of a string and decreases with increasing length or mass

Question 12

How does the natural frequency change for vibrating tubes?

Answer 12

the natural frequency decreases with increasing tube length and is higher for open tubes than for closed tubes

Question 13

What is the rule to remember with natural frequencies?

Answer 13

short things have higher natural frequencies than long things

Question 14

What happens when waves hit an object at its natural frequency?

Answer 14

When waves hit an object at its natural frequency, it can cause resonance, which may lead to significant vibrations or even structural failure, as demonstrated by the Tacoma Narrows Bridge disaster.

Question 15

What are the important properties of light?

Answer 15

• absorption
• diffraction
• reflection
• transmission
• refraction

Question 16

What occurs during the absorption of light?

Answer 16

absorption occurs when a material takes up light energy and is not transmitted at all, resulting in the material appearing black if all light is absorbed. (light energy is not propagated)

Question 17

How does diffraction affect wave behavior?

Answer 17

Diffraction allows waves to bend around obstacles; longer wavelengths diffract more than shorter wavelengths.

Question 18

What is reflection in the context of light?

Answer 18

Reflection is the redirection of light energy when it strikes a surface, such as a shiny mirror.

Question 19

What is transmission in the context of light?

Answer 19

Enger that is passed on through a surface (when it is neither reflected nor absorbed by the surface). For example windows

Question 20

What is refraction?

Answer 20

Refraction is the alteration of light energy as it passes into another medium, changing its direction, such as light entering water from air.

Question 21

What is the particle-wave duality of light?

Answer 21

Light exhibits both wave-like and particle-like properties, depending on the experiment being conducted.

Question 22

What is the significance of the boundary between air and the cornea in the eye?

Answer 22

It is where the strongest refraction occurs, crucial for focusing light on the retina.