KCL Section 3: Waves and Photons Flashcards
Describe the difference between longitudinal and transverse waves
Transverse: Displacement of the medium is perpendicular to the direction of propagation of the wave.
Longitudinal: Displacement of the medium is parallel to the direction of propagation of the wave.
Describe the difference between mechanical and electromagnetic waves
Mechanical waves: these waves require a medium for transmission
Electromagnetic waves: these waves are constantly varying electric and magnetic fields
Define Displacement
Displacement: the position of a particular point on a wave, at a particular instant in time, measured from the mean (equilibrium) position. (Symbol: various, often x; SI units: m.)
Define Amplitude
Amplitude: the magnitude of the maximum displacement reached by an oscillation in the wave. (Symbol: A; SI units: m.)
Define Frequency
Frequency: the number of complete wave cycles per second. This may sometimes be measured as the number of complete waves passing a point per second. (Symbol: f; SI units: hertz, Hz.)
Define Wavelength
Wavelength. the distance between a point on a wave and the same point on the next cycle of the wave. For example, the distance between adjacent wave peaks. (Symbol: A; SI units: m.)
Define Period
Period: the time taken for one complete oscillation at one point on the wave. This will also be the time taken for the wave to travel one wavelength. (Symbol: T, SI units: s.)
Draw a Displacement-time graph
Sin graph
What does the phase of an oscillation refer to?
The phase of an oscillation refers to the position within a cycle that a given point occupies, relative to the onset of the cycle.
What is a radian
1 radian: the angle subtended by an arc which is equal in length to the radius
1 rad to degrees?
1 rad ≈ 57.296 degrees
π rad to degrees?
π rad = 180 degrees
2π rad to degrees?
2π rad = 360 degrees = full circle
What is antiphase?
Antiphase is 180degrees or π rad out of phase
