Light and Sound Waves Quiz

Wave Properties

• Waves can be bunched together or spaced apart, causing a change in pitch, as seen in the example of an ambulance siren.

Reflection

• Waves can be reflected when traveling from a medium of low optical density to one of higher optical density.
• The law of reflection states that the angle of incidence is equal to the angle of reflection.
• Frequency, wavelength, and speed remain unchanged during reflection.

Refraction

• Waves can be refracted, which changes their speed, when entering a new medium.
• When entering a denser medium, the wave slows down and bends towards the normal.
• When entering a less dense medium, the wave speeds up and bends away from the normal.
• In all cases, the frequency remains the same, but the wavelength changes, resulting in a change in velocity.

Electromagnetic Spectrum

• The electromagnetic spectrum includes different types of radiation, listed in order of decreasing wavelength and increasing frequency.
• The main groups of the electromagnetic spectrum include:
  • Visible light (ROYGBIV)
  • Other types of electromagnetic radiation (e.g. X-rays, gamma rays)
• Electromagnetic waves travel at the same high speed in a vacuum and approximately the same speed in air.

Light

• Light waves are transverse waves that can be reflected and refracted.
• Reflection of light can be shown using a ray diagram.
• Refraction of light occurs when it passes through a glass slab at an angle to its normal.
• Snell's law relates the angle of incidence and angle of refraction to the refractive index of a medium.

Total Internal Reflection

• Total internal reflection occurs when the angle of incidence is greater than the critical angle.
• At the critical angle, light will travel along the boundary between two media.
• Total internal reflection requires the light to travel from a more optically dense medium to a less optically dense medium.

Optical Fibres

• Optical fibres use total internal reflection to transfer information by light, even when bent.
• Optical fibres are used in medicine (endoscopes) and communications (high-speed data transfer).

Sound Waves

• Sound waves are longitudinal waves that can be reflected and refracted.
• The range of audible frequencies for a healthy human ear is 20 Hz to 20000 Hz.
• The speed of sound in air can be measured using the formula speed = distance/time.
• An oscilloscope connected to a microphone can display a sound wave and find its frequency and amplitude.
• The amplitude of a sound wave determines its loudness, and the frequency determines its pitch.