Ch4 Waves Flashcards
Define mechanical waves.
Waves that pass through a substance eg. sound, seismic waves
Define electromagnetic waves
Oscillating electric and magnetic fields that progress without the need of a substance. Eg. radio waves, microwaves etc
Define longitudinal waves
Direction of vibration of particles parallel to direction in which wave travels. Eg. sound, primary seismic waves
Define transverse waves.
Direction of vibration perpendicular to the direction of wave travel. Eg. electromagnetic waves, secondary seismic waves.
What conditions are necessary for polarisation?
Transverse waves are plane polarised if the vibrations stay in one plane only
Define amplitude
Max displacement of a vibrating particle
Define frequency
Number of cycles per second
Define period. Include equation.
Time taken for one complete wave to pass a fixed point. Period=1/f
Wave speed c=?
wave speed c= frequency × wavelength
Define wavelength
Least distance between two adjacent vibrating particles with same displacement and velocity at same time.
Define phase difference.
Phase difference=?
Two particles at same frequency is equal to the fraction of the cycle between two particles.
Phase difference= 2πd/wavelength
What effect does making a slit smaller have on diffraction?
Diffraction increases
What effect does making the wavelength shorter have on diffraction?
Diffraction decreases
Describe the principal of superposition
When two waves meet their total displacement at a point is equal to the sum of the individual displacement
What do you need to produce interference?
A coherent source, same frequency and constant phase difference
