Waves 1 Flashcards Preview

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Flashcards in Waves 1 Deck (13):
1

define a progressive wave. define a standing wave

-progressive wave: transfers energy and shape
-standing wave: energy is trapped in packets

2

outline the differences between transverse and longitudinal waves

-transverse: oscillations perpendicular to the direction of wave travel
-longitudinal: oscillations parallel to the direction of wave travel

3

define displacement. define amplitude

-displacement: the distance of a particle from its equilibrium position
-amplitude: the maximum displacement of a particle

4

define wavelength, frequency and period

-wavelength: the distance between two adjacent peaks of a wave
-frequency: the number of waves that pass a point per unit time, f=1/period
-period: the time taken for one complete oscillation

5

define phase difference and path difference

phase difference: the amount in radians that two points on a wave differ (or on two different waves)
path difference: the amount in metres that two points on a wave differ (or on two different waves)

6

what is the equation for wave speed

v=fλ
for EM waves, c=fλ

7

outline reflection key points

-a wave hitting a boundary between media and changing direction, but staying in the original medium
-angle of incidence = angle of relection

8

outline refraction key points

-a wave reaching the boundary between two media and changing speed, therefore changing direction
-when light slows down (e.g Air to Glass) it bends AGAINST the normal
-when light speeds up (e.g Glass to Air) it GOES AWAY from the normal

9

outline diffraction key points

-when a wave enters a gap, if the gap size is equal to or smaller than the wavelength, the wave spreads out.
-can also occur when a wave travels around an obstacle, if the obstacle is a similar size to the wavelength
helps radio waves reach places behind hills

10

outline polarization key points

-unpolarized waves are waves where the oscillations are in all directions
-polarizing filters make sure only waves with oscillations in one direction can get through
-only transverse waves can be polarized
-used in sunglasses

11

what is the formula for intensity of a wave, and what is it proportional to

Intesity = Power/Area
Intensity ∝ amplitude²

12

what are the approximate wavelengths of each wave in the EM spectrum

gamma: <1pm
x-ray: 1pm-10nm
ultraviolet: 10nm-400nm
visible light: 400nm-700nm
infra-red: 400nm - 1mm
microwaves: 1mm-1m
radio waves: >1m

13

how do you calculate the refractive index of a medium

n = speed of light in a vacuum/speed of light in the medium