Reflection and refraction

Question 1

what does the reflection of sound cause?

Answer 1

echoes

Question 2

what does the law of refraction state?

Answer 2

angle of incidence = angle of reflection

Question 3

where are the angles of incidence and reflection measured?

Answer 3

between the light ray and the normal

Question 4

what is the relationship between wavelength and wave speed at a given frequency of light?

• give an example of this
• how can this effect be demonstrated?

Answer 4

the wavelength is proportional to the wave speed

• if a wave slows down, its wavelength will decrease
• using wave front diagrams

Question 5

what do wave front diagrams show?

Answer 5

that as a wave travels across a depth boundary it slows down and the wavelength decreases

Question 6

Although the wave slows down, why does its frequency remains the same? d

Answer 6

because its wavelength is shorter

Question 7

define ‘absorbed’

Answer 7

Energy is ‘taken-in’ by the material and the internal energy of the material will increase

Question 8

define ‘transmitted’

Answer 8

A wave is passed across or through a material (medium)

Question 9

Common examples of absorption of wave energy: (3)

Answer 9

• waves hitting the beach usually give most of their energy to the sand
• sunlight landing on a face is mostly absorbed, warming the skin
• sound waves hitting thick curtains give up their energy and the sound is muffled

Question 10

Common examples of transmission of wave energy: (3)

Answer 10

• sea waves passing a shallow area continue with their energy mostly unchanged
• light passing through a glass window continues with over 95% of its energy
• ultrasound waves scanning a baby pass from flesh into bone and continue with enough energy for the machine to detect the echo

Question 11

Effect of wavelength on absorption in a greenhouse: (5)

Answer 11

• ultraviolet light has a very short wavelength, and this is mostly transmitted by the glass.
• plants, soil and floor in the greenhouse mostly absorb ultraviolet, and their temperature rises.
• plants, soil and floor emit infrared light which has a longer wavelength that is mostly reflected by glass.
• infrared cannot escape the greenhouse and reflects until it is re-absorbed by objects inside the greenhouse.
• amount of energy in the greenhouse rises so its temperature increases.