11.6-11.9 Waves 1 Quizlet Cards Flashcards
What is the difference between mechanical waves and electromagnetic waves?
EM waves don’t require a medium.
What is an electromagnetic wave?
An oscillation of the electric and magentic fields at right angles to each other.
What is the speed of all EM waves in a vacuum/air?
3x10⁸ms⁻¹
List the regions of the EM spectrum in order of increasing wavelength.
Radio waves, Microwaves, Infrared, Visible Light, Ultraviolet, X-rays, Gamma rays
Which two regions of the EM spectrum overlap?
X-rays and gamma rays.
State the range of wavelengths (in powers of 10) of radio waves
> 10⁻¹
State the range of wavelengths (in powers of 10) of microwaves
10⁻¹ - 10⁻³
State the range of wavelengths (in powers of 10) of infrared
10⁻³ - 10⁻⁶
State the range of wavelengths of visible light
7x10⁻⁷ - 4x10⁻⁷
State the range of wavelengths (in powers of 10) of ultraviolet
10⁻⁷ - 10⁻⁸
State the range of wavelengths (in powers of 10) of X-rays
10⁻⁸ - 10⁻¹³
State the range of wavelengths (in powers of 10) of gamma rays
<10⁻¹⁰
Why can’t longitudinal waves be polarised?
Longitudinal waves already only have a single driection of oscillation.
What is the effect of a polarising filter?
It only transmits the component of the oscillations parallel to the filter
What is the effect of perpendicular polarising filters
No light is transmitted
Give a use of polarising filters.
LCD screens, 3D TV, polarimetry in manufacturing, anti-glare sunglasses
What effect does reflection have on the polarisation of light?
Reflected light is partially polarised in the plane of the surface.
What effect does scattering light have on polarisation?
Scattered light is polarised
Which wave property always remains constant when a wave travels from one medium to another?
Frequency
When entering a material with a higher refractive index what happens to wave speed?
decreases
When entering a material with a lower refractive index what happens to wavelength?
increases
What is the definition of the refractive index of a material
Speed of light in a vacuum/Speed of light in material
What are the angles of incidence and refraction measured relative to?
The normal to the boundary
Which way do waves refract when entering a material with a higher refractive index?
Toward the normal
Which way do waves refract when entering a material with a lower refractive index?
Away from the normal
What is the angle of refraction at the critical angle?
Ninety degrees
What are the conditions required for total internal reflection?
Wave must be travelling in a material with a higher index and meeting a boundary with a material of lower refractive index. The angle of incidence must be greater than the critical angle.
