Topic 3: Waves Flashcards
What is the primary characteristic of waves?
Waves transfer energy without transferring matter.
What illustrates wave motion in ropes and springs?
Vibration (oscillation) demonstrates wave motion in ropes and springs.
What is the direction of vibration in a transverse wave?
The direction of vibration is at right angles to the direction of propagation.
Which waves are transverse?
Electromagnetic radiation, water waves, and seismic S-waves are transverse.
What is the direction of vibration in a longitudinal wave?
The direction of vibration is parallel to the direction of propagation.
Which waves are longitudinal?
Sound waves and seismic P-waves are longitudinal.
What are the key features of a wave?
Wavelength, frequency, crest (peak), trough, amplitude, and wave speed.
What is the equation for wave speed?
v=fλ
What happens to waves during diffraction?
Waves undergo diffraction when passing through a narrow gap.
How does wavelength affect diffraction?
The size of the wavelength affects the amount of diffraction through a gap.
What is the angle of incidence equal to in reflection?
The angle of incidence is equal to the angle of reflection.
What is a plane mirror’s image like compared to the object?
The image is the same size, at the same distance from the mirror, and laterally inverted.
What is the nature of the image formed by a plane mirror?
The image formed is virtual.
What is refraction?
Refraction is the change in direction of a light ray passing from one medium to another.
What is refractive index?
Refractive index, n , is the ratio of the speed of a wave in two different regions.
What is the equation for refractive index?
Sin i
N = ———
Sin r
What is the critical angle?
The critical angle is the angle of incidence at which the angle of refraction is 90°, above which all light is totally internally reflected.
What are optical fibres used for?
Optical fibres use total internal reflection for transmitting light signals over long distances.
What is the speed of electromagnetic waves in a vacuum?
The speed of electromagnetic waves in a vacuum is 3.0×10^8m/s.
What are some applications of radio waves?
Radio waves are used for radio and television transmissions and radar.
What is the harmful effect of excessive exposure to X-rays?
Excessive exposure to X-rays can cause mutation or damage to cells in the body.
How is sound produced?
Sound is produced by vibrating sources.
What are compressions in sound waves?
Compressions are regions of higher pressure where particles are closer together.
What is the range of frequencies audible to humans?
The range of frequencies audible to humans is 20Hz to 20kHz.
