Electromagnetic Waves and Sound Exam

Who combined electric and magnetic fields to form an electromagnetic field and showed that anytime any electric current oscillates in a wire or in a space, it generates an electromagnetic wave that travels at the speed of light?

James Clerk Maxwell

Light is an

Electromagnetic Wave

Who calculated the speed of light?

Michelson

Light travels so fast, it can travel 7.5 times around he earth in

7.5 seconds

What is the closest star (other than the Sun) and how far away is it?

Alpha Centauri and 4 lights years

Who argued that light travels in waves?

Hooke & Huggens

Newton postulated that light rays consist of

Streams of particles

Who was correct? Hooke and Huggens or Newton?

Both

In waves, the highest place is a

Crest

In waves, the lowest place is a

Trough

The speed of the propagation of an electromagnetic disturbance is the same as

Speed of light (3x 10 ^ 10 cm/sec)

The magnitude of a disturbance, or total displacement of a wave

Amplitude

Speed

Wavelength x Frequency

When two different waves reach a single point in space at the same time and combine

Interference

When two waves of the same frequency in shape meet crest to crest and trough to trough, they are

In phase

What scientist dealt with the wave nature of light and completed experiments on the wave nature of light

Young

What experiment did Young used to determine that light produces interference and thus acts like a wave?

Double slit experiment

When light shines on a slotted plate, Young saw

Alternate bands of light and dark on a screen

When a ray of light initiates an electric current by the outermost electrons of a metal being dislodged by a beam of light

The photoelectric effect

A key observation of the photoelectric effect is that the kinetic energy of the emitted electrons is related to the frequency of incident of light and not to its

Intensity

Who postulated that light waves are emitted discontinuously in quanta

Planck

What are individual packets of light; can have only one of a definite set off quantized value of energy

Quanta

Once an electron receives enough energy it will

Leave an atom

Electrons gain energy equal to the photon absorbed. This is an excited electron. And excited electron _____ this photon when it falls back to a lower level

Emits

Who is responsible for the postulate that all matter exhibits wave behavior?

Lorenz

Whenever a charged particle accelerates and an electromagnetic wave is emitted

Emissions

When the electron is in its lowest energy level

Ground energy state

Electromagnetic waves from where have little influence or effect on the environment; barely detectable

Electric wires

What are detectable with the use of good equipment?

Radio waves

What transmits microwaves then searches for reflected radiation?

Radar

What are used for detection of microwaves, the largest of these is located in the Philippines

Radio telescopes

Name a natural infrared sensor

Snakes

Humans use artificial infrared sensors to find

Diseased trees

What are produced by boiling electrons off of metal electrode and accelerating them through a potential of 100,000 volts onto a positive plate. These electrons transfer the energy to the positive plate which emits the rays. Also used industrially to search for flaws and welds and metal castings

X-rays

Protons emitted by nuclear transformations

Gamma rays

Six uses for lasers

Melt holes in small jewels, computer technology to burn microscopic holes in computer tape, global surveying, used by surgeons to weld displaced retina back into position without disturbing the rest of the eye, 3D photographs

Used for cutting cloth

Pencil lasers

Two types of waves

Transverse and longitudinal

Characteristics of transverse waves

Are electromagnetic waves, have crests and troughs, will travel in a vacuum, wave propagation is perpendicular to wave velocity

Characteristics of longitudinal waves

Sound waves/elastic waves, like action in a coiled spring, will not travel in a vacuum, wave propagation and wave of velocity are in the same direction, travel faster and denser medium

Two functions of ears

Range and direction finder, helps people balance

Name for the outer ear; functions and funneling sound waves to the external ear

Auricle or pinna

Inside end of the external ear canal

Ear drum

Form a mechanical bridge between the inner ear and the eardrum

Ossicles

Of the obstacle bones, this is the hammer

Malleus

Of the ossicle bones, this is the anvil

Incus

Of the ossicle bones, this is the stirrup

Stapes

Functions of the inner ear

To convert sound induced mechanical waves to nerve impulses and aid and maintaining balance and spatial orientation

Responsible for the conversion of sound induced mechanical vibrations into nerve impulses and contains fluid

Cochlea

Thousands of tiny hairs that convert vibrations into nerve impulses

Organ of Corti

Connects the organ of Corti to the brain

Auditory Nerve

Sounds in which compressions and rarifications of air alternate sinussoidally (like sine waves)

Pure Sounds

Musical sounds are classified as

Quality, depth, or richness

What is the same regarding a note on different instruments? What causes a different sound?

Fundamental frequency & Overtones

The human ear is most sensitive to pure tones at about

4,000 hz

Sound below 50 hz; humans can't hear this

Infrasounds

Sounds above 15,000 Hertz

Ultrasounds

Five uses of ultrasounds

Welding, cutting, drilling, cleaning, and used in medical diagnosis

Speed slower than the speed of sound

Subsonic

Speed that is the same as the speed of sound

Sonic

Speeds greater than the speed of sound

Supersonic

Speed of sound

Mach 1

Caused by an object being ahead of the sound waves

Sonic boom