Module Two Phyiscs : TBR

Simple Harmonic motion is a periodic motion which occur when the acceleration of the mass is proportional to the displacement from a fixed point and is directed towards that point.

Periodic Motion a motion that repeats itself after equal intervals of time.

Resonace is a phenomenon that occurs when energy is added to a system at one of its natural frequencies of oscillation producing a very large amplitude within the system.

Light Damping allows for the gradual reduce in periodic motion. (Air acts as a damper for a simple pendulum)

Critical Damping allows for one oscillation before periodic motion stops. (Shock absorbers in cars)

Over Damping the system fails to oscillate.  (Doors of an auditorium, so that the door closes slowly)

A transverse wave is produced when the oscillation of a particle is perpendicular to the direction of propagation (energy transfer). It consist of a series of crest and throughs.

A longitudinal wave is produced when oscillations of a particle is parallel to the direction of propagation (energy transfer). It consist of a series of compressions and rarefactions.

A progressive wave is a wave that is produced by the vibrations and the energy is transferred from one location to another. Light is a transverse progressive wave and Sound is a longitudinal progressive wave.

The maximum displacement of a particles in a wave.

The distance between two points in a wave in which the wave repeats itself.

The time taken for one oscillation.

The number of oscillations that occur per unit time or in one second.

Of a point on a wave is the distance from the centre line (x axis) to that point.

The intensity of a wave is directly proportional to the square of the amplitude of the oscillation.

Phase of a particular point on a wave is a measure of the fraction of oscillation that has been complete.

Polarization is the process by which a plane or mode of vibration is take out from any transvers wave.

The principle of superposition states when two or more waves arrive at a point the resultant displacement at that point is the algebraic sum of the individual displacement of each wave

Constructive inference occurs when two waves in phase superimpose, the resultant displacement is greater that either of the two waves.

Destructive inference occurs when two waves superimpose completely out of phase, the resultant displacement is zero.

Youngs Double Slit experiment. Where monochromatic light travelled through two slits the light diffracts and the diffracted rays. The diffracted waves superimpose constructively causing bright fringes and destructively creating dark fringes. Thus, proving light is a wave.

Coherent waves have the same frequency and hence a have a constant phase difference.

1) The amplitudes of the waves must be similar.

2) The waves must be the same type.

3) The waves must be coherent (same frequency and hence a constant phase difference)

4) If the waves are polarized, they must be  in the same plane of polarization

5) The waves must meet at a point.

Diffraction is the spreading out of a wavefront as it passes through small gaps or around edges of an obstacle.

Formed by the superposition of two progressive waves of the same type, amplitude and frequency travelling with the same speed in opposite directions.

Nodes are points along a stationary wave where the particles are at rest hence their displace is zero.

Antinodes are point midway between nodes on a stationary wave where the particle’s displacement is twice the amplitude of either progressive wave.

Very thin Glass surrounded by cladding. The cladding is less optically dense as a result its critical angle is larger. Therefore, when light Is incident to the cable at an angle of incidence greater than the critical angle total internal refection occurs continuously until the information store in light to transmitted to another location.

In the day, the air is closer to the ground is hotter and as a result less dense. When sound is being transmitted the sound has a tendency to refract going from the less hot air closer to the ground to the cooler air above.

In the night the exact opposite happens. The air closer to the ground is cooler and in turn the air above is warmer as a result when sound is transmitted it has a tendency to go from the less dense hot air to the cooler air closer to the ground. Things are therefore head more clearly in the night.

Consist of an oscillating electric field and magnetic field at right angles to each other.

Used to transmit signals in telecommunication and navigation systems.

Produced by transmitters

Used to heat food and telecommunication

Produced by Klystron Tubes

Used carry signals wirelessly over short distances (TV Remote) and also used in fibre optics

Produced by all hot objects

Red -536

Orange

Yellow

Green - 386

Blue

Indigo - 334

Violet - 310

Used to kil bacteria and produce vitamin D.

Produed by mercury vapor lamps and electric arcs

Used to get imaging of internal organs, tissues and bones.
Produced by X-Ray Tubes

Firstly, sound is retrieved and reflected by the pinna through the ear canal onto the tympanic membrane. These vibrations are then transmitted through the inner ear by a lever like system consisting of three bones the hammer, anvil and stirrup. The vibrations are transmitted through the fluid of the cochlea. Tiny sensitive “hair” cells on the basilar membrane resonates producing electrical signal that are sent to the brain where they are processed.

The sensitivity of the human ear is the ability to detect the smallest fractional change in intensity of a sound.

Light incident to the eye is refracted by the cornea due to the cornea eye boundary. The intensity of this is determined by the iris. The refracted light travels through a fluid, aqueous humour and hit the lens of the eye. This convex lens is suspended by the ciliary muscles on both sides which allows it to change its size. For object closer the lens is made thicker (small focal length) so the power of the lens is relatively small. For object farther away the lens is thinner (big focal length) so the power of the lens is stronger. The reflected ray of light must fall on the retina for an image to be formed therefore the lens aims to ensure this occurs. When the image is formed at the retina, the nerve cells there namely cone, and rods sends this information through the optical nerves to the brain to be interpreted.

Accommodation is the eyes’ ability to adjust the focal length of the lens as to focus images formed from objects far distances away.

Depth of focus of the eye is the range of the image distances which give a sharp image on the retina.

Depth of field of the eye is the distance moved by the object while the image stays in focus.