4.3 Wave properties 1

Question 1

What are the 3 properties of waves?

Answer 1

» Diffraction
» Refraction
» Reflection

Question 2

What is a ripple tank?

Answer 2

» A shallow transparent tray of water with sloping sides

Question 3

What is the purpose of slopes on the ripple tank?

Answer 3

» Prevents waves reflection off the sides of the tank

Question 4

What are wavefronts?

Answer 4

» The waves which are observed in a ripple tank, which are lines of constant phase

Question 5

In which direction do waves travel in a ripple tank?

Answer 5

» Right angles to the wavefronts

Question 6

What happens when waves are directed at a certain angle to a flat surface?

Answer 6

» Angle between reflected wave front is same as the incident wavefront
» Direction of reflected wave is the same as the incident wavefront

Question 7

How are wavefronts actually formed on the piece of paper?

Answer 7

» Wave Crest acts like a convex lens and concentrates the light onto the screen

Question 8

What happens when the wave changes speed when it hits a boundary?

Answer 8

» Also changes wavelength

Question 9

What is refraction?

Answer 9

» When the wavefronts approach at an angle to the boundary, they change direction as well as changing speed

Question 10

Describe what you would observe when a wave changes medium from deep to shallow?

Answer 10

» The wave moves more slowly in the shallow water, the wavelength is smaller in the shallow water so they change direction

Question 11

Why does light change direction when it moves from air to glass?

Answer 11

» Light moves more slowly in glass

Question 12

What is diffraction?

Answer 12

» When waves spread out after passing through a gap or round in an obstacle

Question 13

What does a more narrow grip mean?

Answer 13

» The more waves that spread out

Question 14

What does a more longer wavelength mean?

Answer 14

» The more the waves spread out

Question 15

Why is a bigger dish a problem?

Answer 15

» Even though a bigger dish, the stronger signal it can receive
» Bigger dish reflects radio waves to a smaller focus, because it diffracts the waves less
» Therefore needs to be aligned more carefully then a smaller dish

Question 16

What is the helpful neumonic to remember refraction?

Answer 16

» RNAR

Question 17

What does RNAR stand for?

Answer 17

» R stands for ray - draw the ray until the boundary
» N stand for normal line between the boundary of the mediums
» A stands for angle of incidence
» R stands for refraction - usually reflected ray bends away from normal
» Draw wavefronts perpendicular to the reflected ray

Question 18

Do waves travel faster in shallow water or deeper water?

Answer 18

» Travel faster in deep water

Question 19

What happens to the rays if they travel from deeper water to slower water?

Answer 19

» Travel slower
» Bend towards the normal