Physics

SELECTED TOPIC OF PHYSICS
UNIT 4
simple harmonic motion (SHM) is the motion of a simple harmonic oscillator, a periodic motion that is neither driven nor damped.
The motion is periodic if the body oscillates about an equilibrium position in a sinusoidal pattern. Each oscillation is identical, and thus the period, frequency, and amplitude of the motion are constant.
Frequency is the number ofoccurrences of a repeating event per unit time.
The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency.
harmonic motion when a particle experiences repeated movement about a position of stable equilibrium, or balance.
periodic motion this motion is repeated at regular intervals.
DAMPED MOTION is the linear motion an elastic restoringforce proportional to its displacement and to a frictional force in the direction opposite to its motion and proportional to its speed.
Simple Pendulum is one which can be considered to be a point mass suspended from a string or rod of negligible mass. It is a resonant system with a single resonant frequency. For small amplitudes, the period of such a pendulum can be approximated by:
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Hooke's law of elasticity is an approximation that states that the extension of a spring is in direct proportion with the load added to it as long as this load does not exceed the elastic limit.
Mathematically, Hooke's law states that
Where:
x is the displacement of the end of the spring from its equilibrium position;
F is the restoring force exerted by the material; and
k isthe force constant (or spring constant) in SI units kg/s2.

WAVES PHENOMENA
Reflection is the change in direction of a wavefront at an interface between two different media so that the wavefront returns into the medium from which it originated.
The law of reflection states that the angle of incidence of a wave or stream of particles reflecting from a boundary, conventionally measured from thenormal to the interface (not the surface itself), is equal to the angle of reflection, measured from the same interface,

ANGLE OF INCIDENCE IS the angle of incidence of a ray or beam is the angle measured from the ray to the surface normal.

angle of reflection of a ray or beam is the angle measured from the reflected ray to the surface normal. It is measured between the ray and a linenormal to the surface that intersects the surface at the same point as the ray
Refraction is the change in direction of a wave due to a change in its speed. This is most commonly observed when a wave passes from one medium to another at an angle.
LAW OF REFRACTION OR SNELL’S LAW gives the relationship between angles of incidence and refraction for a wave impinging on an interface between two mediawith different indices of refraction. The law follows from the boundary condition that a wave is continuous across a boundary, which requires that the phase of the wave be constant on any given plane, resulting in
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where and are the angles from the normal of the incident and refracted waves, respectively.

Diffraction refers to various phenomena which occur when a wave encounters anobstacle. It is described as the apparent bending of waves around small obstacles and the spreading out of waves past small openings.
interference is the addition (superposition) of two or more waves that results in a new wave patter.
CONSTRUCTIVE INTERFERENCE occurs when the amplitudes of two waves have the same sign (either both positive or both negative), they will add together to form a wavewith a larger amplitude.

DESTRUCTIVE INTERFERENCE occcurs when the two amplitudes have opposite signs, they will subtract to form a combined wave with a lower amplitude.

standing wave, also known as a stationary wave, is a wave that remains in a constant position. This phenomenon can occur because the medium is moving in the opposite direction to the wave, or it can arise in a stationary...