4.3 - Wave properties 1 Flashcards
what can be used to show wave properties
a ripple tank with a shallow transparent tray of water with sloping sides to prevent water from reflecting of the sides of the tank
what are the waves observed in a ripple tank referred to as
wavefronts which are lines of constant phase
the direction in which a wave travels is at right angles to the wave front
definition of reflection
the change in direction of a wavefront at an interface between 2 different media so that the wave front returns to the medium in which it originated
why is the angle of incidence equal to the angle of reflection
when waves are reflected at a flat surface they are reflected of in the same angle
Therefore the angle between the reflected wave front and the surface is equal to the angle between the incident wavefront and the surface
How is reflection observed using light
shining a light ray at a plain mirror and measuring the angle of incidence and reflection to check that they are equal
definition of refractions
the change of direction of a wave when it crosses a boundary into a different medium and changes speed
why does the wave change direction during refraction
if the wavefronts approach the medium at an angle then one side of the wavefront will hit the boundary before the other causing it to change speed and therefore causing the wave to bend
how is refraction of light observed
shining a light ray into a glass block at an angle
The light ray changes direction when it hits the boundary as light travels more slowly in glass than air and therefore the light bends towards the normal
definition of diffraction
the spreading of waves after passing through a gap or around an obstacle
how can diffraction be seen using waves
sending straight waves in a ripple tank through a gap or around an object
what happens when the gap is narrower
more diffraction occurs
(waves become more spread out)
what happens if there is a longer wavelength
the more diffraction occurs
(the waves spread out more)
what creates the diffraction effect when passing through a gap
the wavelets from the points on the wavefront can only travel in the direction that the wave is travelling (not in the reverse direction)
they all combine together to form a new wavefront spreading beyond the gap
why do satellite dishes in Europe need to point south
because the satellites orbit earth directly above the equator
why will a bigger satellite dish receive a stronger signal
more radio waves a reflected by the dish onto the aerial
