Wave Optics and the EM Spectrum

Wave Optics within the scope of Division B Optics Science Olympiad.

What is an electromagnetic wave?

A wave formed by vibrating electric and magnetic fields that we know as light.

What is the wave-particle duality?

Light acts as both a particle and a wave.

What is diffraction?

The bending of waves around obstacles and the spreading of waves as they pass through openings; it occurs with all types of waves, including sound, water, and light.

What is polarization?

A property of transverse waves that specifies the geometric oriegntation of the oscillations.

What is young’s double slit?

An experiment where light is passed through two tiny slits that are very close together and projected on a screen in front of the slits there is a pattern of bright spots and dark spots rather than two bright spots as one would expect.

What are diffraction gratings?

A variation on young’s double slit where instead of two slits there are many, and they are often closer together.

What is constructive interference?

Wave interference that occurs when two waves are ‘in phase’ or lined up. The resulting wave is bigger than the two waves it came from.

What is destructive interference?

Interference that occurs when two waves are ‘pi shifted’ or opposite each other. The resulting wave is smaller than the two waves it came from and sometimes is not visible at all.

What are the two types of polarization?

Circular and linear.

What is circular polarization?

Polarization composed of two dual-perpendicular electromagnetic plane waves with an identical amplitude and a 90-degree variation in phase.

What is linear polarization?

Oscillations are confined to a single plane.

What is scattering?

Scattering is the process where particles or waves are deflected or dispersed in different directions when they interact with obstacles or other particles in their path.

What is elastic scattering?

A type of scattering where no energy is lost.

What is inelastic scattering?

A type of scattering where energy is lost.

Why is the sky blue?

Because blue light is scattered most efficiently by the atmosphere.

What is Huygen’s principle?

Every point on a wave can be regarded as a source for new wavelets.

How does single slit diffraction work?

When some of the wavelets created by Huygen’s principle are blocked by the single slit, a new interference pattern is what results rather than the next wavefront.

What are radio waves?

Electromagnetic waves created by electric currents, and the highest wavelength, lowest frequency, and lowest energy band of EM radiation.

What do AM and FM stand for?

Amplitude modulation and frequency modulation.

What are AM waves?

Radio waves that have a constant amplitude and carry information by a change in frequency.

What are FM waves?

Radio waves with a constant frequency that carry information by a change in amplitude.

What are the sections of the electromagnetic spectrum from lowest to highest frequency?

Radio waves, microwaves, infrared, visible, ultraviolet, x-rays, and gamma rays.

What are microwaves?

Electromagnetic waves that can be produced both by electric currents and thermal oscillation of molecules.

What is infrared?

Electromagnetic radiation produced by the thermal oscillation of molecules.

What is ultraviolet?

Electromagnetic radiation that is mostly blocked by the ozone layer and causes sunburn as well as skin cancer.

What are x-rays?

The part of the electromagnetic spectrum that is often associated with medical imaging and is emitted by extremely hot objects in space (the hotter the object, the shorter the wavelength).

What are gammas rays?

Electromagnetic radiation emitted by the nuclei of atoms. It is found in the most cataclysmic of interactions between astrophysical bodies: supernovae and the mysterious gamma ray bursts.

What is infrared used for?

It is used to view heat, and is the wavelength that night vision goggles allow you to see.

What are radio waves used for?

Mainly communication and most notably radio.

What are x-rays and gamma rays used for?

Medical imaging and cancer treatment.

What are holograms?

Recordings of optical interference patterns.

How are the energies of the electric field and the magnetic field related to one another?

The stronger the electric field, the stronger the magnetic field.

What is a photon?

A particle of light.

What is wavelength?

The distance from crest to crest on a wave.

What is frequency?

The number of cycles per second.