Chapter 1

Question 1

What is a wave?

Answer 1

A transmission of energy through periodic oscillations, without a net transfer of matter

Question 2

Define a Transverse Wave

Answer 2

The Particles oscillate perpendicular to the direction of energy flow.

Question 3

Give an example of a transverse wave that doesn’t require a medium to travel through

Answer 3

Light

Question 4

Define a Longitudinal wave

Answer 4

The waves move in the same direction (parallel) to the energy flow

Question 5

Give an example of a longitudinal wave

Answer 5

Sound waves

Question 6

Difference of Amplitude in Electromagnetic & Sound waves

Answer 6

In Electromagnetic waves, the amplitude (INTENSITY) tells us how BRIGHT the light is

In Sound waves, the amplitude represents the VOLUME, while Frequency is the PITCH

Question 7

How does the source determine the frequency of a wave?

Answer 7

Wave frequency is determined by how fast the source of the wave is vibrating.
The faster the source is vibrating, the higher the frequency

Question 8

What is Radiation?

Answer 8

The transmission of energy in the form of electromagnetic waves or high-speed particles

Question 9

In order of lower to higher frequency, what is the electromagnetic spectrum?

Answer 9

Radio, Micro, Infrared, Visible Light, UV, X-rays, Gamma Rays

Question 10

Give the percentage of radiation emitted from the sun as infrared, visible light and UV.

Answer 10

Infrared (50%), Visible Light (40%), UV (10%)

Question 11

Define the refractive index

Answer 11

The ratio of the speed of light in a vacuum to the speed of the medium

Question 12

What is Total Internal Reflection?

Answer 12

The reflection of all incident light at a boundary between 2 mediums

Question 13

Explain what happens when light moves into a slower medium with a higher refractive index, such as air into water.

Answer 13

The light bends TOWARDS the normal, thus the angle of refraction will be less than the

Question 14

What is the formula for the refractive index of a medium

Answer 14

n=c(speed of light in a vacuum)/v(speed of light in a medium)

Question 15

What is the minimum value for a refractive index

Answer 15

Equal to or greater than 1

Question 16

What is the formula for refractive indices in 2 different mediums?

Answer 16

n1v1 = n2v2

Question 17

What is Snell’s Law?

Answer 17

The law gives the formula for light passing between mediums, by relating the refractive index of each medium with the Angle of Incidence and Angle of Refraction

Question 18

What is dispersion?

Answer 18

Separation of white light into its colours due to different refractive indices for different frequencies

Question 19

What is a mirage?

Answer 19

An opticul illusion caused by the refraction of light due to changes in AIR TEMP and PRESSURE

Question 20

What causes a rainbow

Answer 20

caused by the dispersion of the Sun’s light through water in the atmosphere

Question 21

What is white light?

Answer 21

The Combination of the continuous visible spectrum of electromagnetic radiation

Question 22

How does dispersion occur?

Answer 22

As different frequencies of light have different refractive indices, when the rays refract, they separate further as you go down

Question 23

What conditions must be met for rainbows to occur?

Answer 23

1. The sun must be behind the observer
2. There must be water in the atmosphere (rain droplets)
3. The observer must be far away from the water droplets
4. Sufficient sunlight reaches the water droplets and reflects light into the observer’s eyes

Question 24

Explain what happens during a rainbow

Answer 24

Each droplet in a rainbow disperses the whole spectrum of light into a cone, but we dont see the whole rainbow from each drop.

Every drop reflects ONE colour, dependent on its location to our eyes.
The combination of ALL THESE RAINDROPS, EACH REFLECTLING colour int our eyes is the WHOLE RAINBOW

Question 25

How are mirages formed?

Answer 25

As light moves through air, its speed changes according to snells law, causing the light to REFRACT and change direction.
When the light refracts enough towards an observer’s eyes, a MIRAGE occurs.

They only occur when the air has a RANGE OF temperatures and densities
for instance, surfaces the heat up easily such as roads transfer heat energy to the air, which creates a GRADIENT of both AIR DENSITY and TEMPERATURE above the road

In Summary, the rays that travel through the temperature gradient change speed, thuis bending continuously with the change in temp utnil either TOTAL INTERNAL REFLECTION OCCURS OR THE LIGHT BENDS ENOUGH TO TURN INTO THE OBSERVER’S EYES.

Question 26

What do Optical Fibres do?

Answer 26

They use total internal reflection to TRANSPORT LIGHT through a cable from one l;ocation to another

Question 27

Why do we use optical fibres to communicate?

Answer 27

Because they can TRANSFER DATA USING A LARGER RANGE OF FREQUENCIES, making it omre efficient for transferring large amounts of data fast.

Question 28

Define Total Internal Reflection

Answer 28

Refers to the situation when the incident ray cannot transmit or refract light into the other medium, and occurs when light travels from a higher refractive index medium to a lower refractive index and the angle of incidence is larger than the critical angle

Question 29

Define Critical Angle

Answer 29

Refers to the angle of incidence when the angle of refraction is 90 degrees