PHYSICS KEYWORD LIST:
Wave: Periodic disturbance travelling through space,
characterised by a vibrating medium.
Progressive Wave: Wave that carries energy from 1 place to
another.
Displacement: Distance of a point on the wave from its
undisturbed or equilibrium position.
Amplitude: Maximum displacement of a wave.
Wavelength: Distance between 2 adjacent points on a wave
oscillating in step with each other.
Period: Time taken for 1 complete oscillation of a point in
a wave.
Frequency: Number of oscillations per unit time of a point
in a wave.
Longitudinal Wave: A wave in which the particles of the medium
oscillate along the direction in which the wave travels.
Transverse Wave: A wave in which the particles of the medium
oscillate at right angles to the direction in which the wave travels.
Compression: Point in a sound wave at which the air pressure
is at maximum.
Rarefaction: Region in a sound wave where the air pressure
is less than its mean value.
Phase Difference: Fraction of a cycle between 2 oscillating
particles, expressed in either degrees or radians.
Intensity: Intensity is the rate of energy transmitted
(power) per unit area at right angles to the wave velocity.
Doppler Effect: Change in frequency or wavelength of a wave
observed when the source of the wave is moving towards or away from the
observer (or the observer is moving relative to the source).
Electromagnetic Spectrum: A family of waves that travel
through a vacuum at a speed of 3 x 108 m/s.
Magnetic Field: Force field in which a magnet, a wire
carrying a current, or a moving charge experiences a force.
Electromagnetic Wave: Transverse waves travel through space
as electric and magnetic fields vibrations.
Electric Field: Force field in which an electric-charged
particle experiences a force.
Plane Polarised: Describes a transverse wave with oscillation in just 1 plane. Only transverse waves can be polarised.
PHYSICS CHAPTER WISE SUMMARY:
A progressive wave carries energy from 1 place to another.
There are two types of progressive waves: longitudinal and transverse. Longitudinal waves have vibrations parallel to the direction in which they travel, whereas transverse waves have vibrations at right angles to that direction.
Displacement is the distance of a point on the wave from its
undisturbed or equilibrium position.
Amplitude is the maximum displacement of a wave.
Wavelength is the distance between 2 adjacent points on a
wave oscillating in step with each other.
The period is the time taken for 1 complete oscillation of a point
in a wave.
Frequency is the number of oscillations per unit time of a
point in a wave.
The phase difference is the fraction of a cycle between
oscillating particles, expressed in degrees or radians.
2 points on a wave separated by a distance of 1 wavelength
have a phase difference of 0o or 360o.
The frequency of a wave is related to its period: f = 1/T.
The frequency of a sound wave can be measured using a
cathode-ray oscilloscope (CRO).
The speed of all waves is given by: wave speed = frequency x
wavelength. (v = fλ)
The Doppler effect is the change in an observed wave
frequency when a source moves with speed. The observed frequency is given by: f0
= ((fs x v)/(v +- vs))
The intensity of a wave is defined as the wave power transmitted
per unit area at right angles to the wave. Intensity = Power/Area.
Intensity has units of W/m2.
The intensity of a wave is directly proportional to the
square of the amplitude. I = A2
All electromagnetic waves travel at the same speed of 3 x 108
m/s in a vacuum but have different wavelengths and frequencies. Electromagnetic
waves are transverse waves.
The regions of the electromagnetic spectrum in order of
increasing wavelengths are gamma rays, X-rays, Ultraviolet, Visible, Infrared,
Microwave, and Radio waves.
A plane-polarised wave has oscillations in just 1 plane. Only transverse waves can be plane-polarised.
Malu’s Law: I = I0 Cos2 angle
PHYSICS IMPORTANT NOTES:
Intensity = Power/Area
Intensity is directly proportional to amplitude2.
I = A2
Speed of the wave = frequency x wavelength. v = fλ
Doppler effect: f0 = ((fs x v)/(v +- vs))
Malu’s Law: I = I0 Cos2 angle
Waves that need a substance to travel are Mechanical Waves. E.g. Sound, Water, Seismic Waves.
Electric current always gives rise to a magnetic field in Electromagnetism.
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