Chapter 3 Flashcards
Waves
Amplitude
The maximum displacement of a wave from the undisturbed position, or maximum change of value from zero
Converging lens
A lens which refracts parallel rays of light such that they converge to meet at a point
Crest of a wave
A wavefront where all the points have their highest displacement
Diverging lens
A lens which refracts parallel rays of light such that they diverge away from a point
Electromagnetic Waves
Waves of the same nature with a wide range of wavelengths made up of oscillating electric and magnetic fields
Focal length
The distance between the optical centre and the principal focus of a lens
Frequency
The number of complete oscillations per second
Longitudinal wave
Direction of vibration of particles of the transmitting medium is parallel to the direction of travel of the wave
Principal focus
Point on the principal axis to which light rays parallel to the principal axis converge, or (if focal point) appear to diverge from
Real image
An image which can be formed on a screen
Transverse wave
Direction of vibration or change of value is perpendicular to the direction of travel of the wave
Trough of wave
A wavefront where all the points have their lowest displacement
Virtual image
An image which cannot be formed on a screen
Wave speed
The distance moved by a point on a wave in 1 s
Wavefront
A line on which the particles or values of the wave are in phase
Wavelength
The distance between corresponding points in successive cycles of a wave
Analogue signal
A signal that can take any value within a range
Compression
Regions where particles of the transmitting medium are closer together
Digital signal
A signal that can only take one of two definite values: high (maximum value) or low (close to 0)
Rarefaction
Regions where particles of the transmitting medium are further apart
Refractive index
The ratio of the speed of a wave in two different media
