p6 waves and optics

Restoring Force

A force that always pushes or pulls the object toward the equilibrium position.

Simple Harmonic Motion

occurs when the net force along the direction of motion obeys Hooke’s law—when the net force is proportional to the displacement from the equilibrium point and is always directed toward the equilibrium point.

Amplitude

the maximum distance of the object from its equilibrium position.

Period

the time it takes the object to move through one complete cycle of motion,

Frequency

is the number of complete cycles or vibrations per unit of time, and is the reciprocal of the period

Elastic Potential Energy

energy stored in a stretched or compressed spring or some other elastic material

Simple Pendulum

another mechanical system that exhibits periodic motion.

Physical Pendulum

A pendulum can be made from an object of any shape.

Damped

The friction reduces the mechanical energy of the system as time passes, and the motion is said to be

Underdamped Oscillation

if the fluid has a relatively low viscosity, the vibrating motion is preserved but the amplitude of vibration decreases in time and the motion ultimately ceases.

Critically Damped

oscillation. If the fluid viscosity is increased, the object returns rapidly to equilibrium after it’s released and doesn’t oscillate.

Overdamped

If the viscosity is made greater still, the system is said to be

Traveling Wave

The bump (called a pulse) travels to the right with a definite speed.

Transverse Waves

the elements of the medium move in a direction perpendicular to the direction of the wave.

Longitudinal Waves

the elements of the medium move parallel to the direction of the wave velocity.

Solition

Another type of wave, that consists of a solitary wave front that propagates in isolation.

Amplitude

The maximum distance the string moves above or below this equilibrium value is called the

Wavelength

The horizontal arrows show the distance between two successive points that behave identically.

Superposition Principle

When two or more traveling waves encounter each other while moving through a medium, the resultant wave is found by adding together the displacements of the individual waves point by point.

in phase and to exhibit constructive interference.

crest meets crest and trough meets trough

constructive interference.

wave with twice the amplitude.

Destructive interference

complete cancellation. crest meets trough,

Compression

a region of high molecular density and high air pressure is called

Rarerfraction

Such a region of reduced density

Audible Waves

are longitudinal waves that lie within the range of sensitivity of the human ear,

Infrasonic Waves

longitudinal waves with frequencies below the audible range.

Ultrasonic Waves

longitudinal waves with frequencies above the audible range for humans and are produced by certain types of whistles.

piezoelectric effect

This method of transforming electrical energy into mechanical energy,

Diffraction

It is now known that light does indeed bend around the edges of objects.

Photoelectric Effect

the result of energy transfer from a single photon to an electron in the metal.

Reflection

part of the light encountering the second medium bounces off that medium.

Refraction

the light passing into the second medium bends through an angle with respect to the normal to the boundary.

Wave Front

a surface passing through the points of a wave that have the same phase and amplitude.

Specular Reflection

The reflection of light from such a smooth surface is called

Diffuse Reflection

Reflection from any rough surface is known as

Normal Line

with a line perpendicular to the surface at the point where the incident ray strikes the surface.

Refraction

The ray that enters the second medium is bent at the boundary

Dispersion

The dependence of the index of refraction on wavelength

Snell Law

the angle of refraction made when light enters a material depends on the wavelength of the light.

Angle of Deviation

A ray of light of a single wavelength that is incident on the prism from the left emerges bent away from its original direction of travel by an angle

Visible Spectrum

The rays that emerge from the second face of the prism spread out in a series of colors known as a

Prism Spectrometer

Prisms are often used in an instrument known as a

Huygens’ principle

all points on a given wave front are taken as point sources for the production of spherical secondary waves, called wavelets, that propagate in the forward direction with speeds characteristic of waves in that medium. After some time has elapsed, the new position of the wave front is the surface tangent to the wavelets.

Total Internal Reflection

can occur when light encounters the boundary between a medium with a higher index of refraction and one with a lower index of refraction

Critical Angle

the refracted light ray moves parallel to the boundary

Real Image

image, light actually passes through the image point.

Vitual Image

light doesn’t pass through the image point, but appears to come (diverge) from there.

Concave Mirror

a spherical mirror with a silvered inner, concave surface; this type of mirror is called a

Converging Lenses

are thicker at the center than at the rim

Diverging Lenses

thinner at the center than at the rim.

focal length

the image distance that corresponds to an infinite object distance.