6.3 wave motion

Question 1

define a progressive wave

Answer 1

progressive wave is a wave in which energy is carried from one point to another by means fo vibrations or oscillations within the waves, without transporting matter

Question 2

define intensity of a wave

Answer 2

intensity is the rate of energy transmitted per unit area perpendicular to the wave velocity (intensity = power over area, intensity proportional to A^2)

Question 3

what are the formulas for 3D and 2D transmission of intensity relating to distance r?

Answer 3

3D: I = power / 4 pi r^2 (sphere surface area)
2D: I = power / 2 pi r h

Question 4

define polarisation

Answer 4

when oscillations in a wave are confined to one direction only, in a plane normal to the direction of transfer of energy of the wave

Question 5

why can sound waves not be polarised?

Answer 5

sound waves are longitudinal waves and do not have oscillations in the plane normal to the direction of transfer or energy of the wave.