Wave Properties and Reflection

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Questions and Answers

What is the normal in the context of reflection?

The normal is an imaginary line perpendicular to the surface at the point of incidence.

Describe the characteristics of an optical image formed by a plane mirror.

The image is virtual, upright, laterally inverted, and the same size as the object.

What relationship holds true regarding the angles of incidence and reflection?

The angle of incidence is equal to the angle of reflection.

How does light behave when it passes from a less dense to a more dense medium?

The angle of incidence is greater than the angle of refraction, meaning the light bends towards the normal. Signup and view all the answers

Define critical angle in optics.

The critical angle is the angle of incidence above which total internal reflection occurs. Signup and view all the answers

What is total internal reflection?

Total internal reflection occurs when light travels from a denser medium to a less dense medium at an angle greater than the critical angle. Signup and view all the answers

What is amplitude and what is its SI unit?

Amplitude is the maximum displacement from the original position, and its SI unit is meters. Signup and view all the answers

What happens to light rays when they pass through a converging lens?

Light rays are refracted to meet at the principal focus, creating a real image. Signup and view all the answers

How is wavelength defined and what is the unit used to measure it?

Wavelength is the horizontal distance between two points that are in phase, measured in meters. Signup and view all the answers

How does a diverging lens affect parallel rays of light?

Diverging lenses spread out parallel rays of light, creating a virtual image. Signup and view all the answers

Define frequency and provide its SI unit.

Frequency is the number of complete cycles in a second, and its SI unit is hertz (Hz). Signup and view all the answers

What is the significance of the refractive index?

The refractive index is the ratio of the speed of light in a vacuum to the speed of light in a medium. Signup and view all the answers

State the equation for calculating the speed of a wave.

The speed of a wave is calculated using the equation v = f x λ. Signup and view all the answers

What distinguishes transverse waves from longitudinal waves?

Transverse waves have particles that vibrate perpendicular to the direction of motion, while longitudinal waves have particles that vibrate parallel to the direction of motion. Signup and view all the answers

What occurs during the dispersion of light in a prism?

White light is separated into its component colors, forming a spectrum. Signup and view all the answers

List the traditional colors of the visible spectrum in order from longest to shortest wavelength.

Red, orange, yellow, green, blue, indigo, violet. Signup and view all the answers

Explain the phenomenon of refraction in waves.

Refraction is the change of direction of a wave when it passes from one medium to another, often due to a change in speed. Signup and view all the answers

What happens to a wave's speed and wavelength when moving from deep to shallow water?

As a wave moves from deep to shallow water, its speed decreases and its wavelength becomes shorter. Signup and view all the answers

What does Snell’s Law describe?

Snell's Law states that the ratio of the sine of the angle of incidence to the sine of the angle of refraction is constant. Signup and view all the answers

What is an optical fiber's primary function?

Optical fibers transmit light signals for telecommunications and data transmission. Signup and view all the answers

Describe the process of diffraction in waves.

Diffraction occurs when a wave spreads as it passes through an opening or around an edge, and it increases when the gap size decreases or the wavelength increases. Signup and view all the answers

What are the harmful effects of excessive microwave exposure on the human body?

Microwaves can cause internal heating of body cells, potentially leading to tissue damage. Signup and view all the answers

How does infrared radiation affect human skin?

Infrared radiation can cause skin burns due to its heat energy. Signup and view all the answers

What are the potential risks of ultraviolet radiation exposure?

Ultraviolet radiation can damage surface cells and eyes, leading to skin cancer and various eye conditions. Signup and view all the answers

Describe the dangers associated with X-rays and gamma rays.

X-rays and gamma rays can cause mutation or damage to cells in the body. Signup and view all the answers

What is the speed of electromagnetic waves in a vacuum?

The speed of electromagnetic waves in a vacuum is approximately $3 imes 10^8$ m/s. Signup and view all the answers

Why are microwaves preferred for communication with artificial satellites?

Microwaves can penetrate walls and require shorter aerials for effective transmission. Signup and view all the answers

What type of waves do Bluetooth devices use for communication?

Bluetooth uses radio waves for communication. Signup and view all the answers

How does digital signaling enhance communication compared to analogue signaling?

Digital signaling allows for increased rates of data transmission and accurate signal regeneration. Signup and view all the answers

What is the nature of sound waves?

Sound waves are longitudinal waves that require a medium to propagate. Signup and view all the answers

Explain how frequency and amplitude influence sound.

Frequency affects the pitch of sound, while amplitude determines its loudness. Signup and view all the answers

What is the frequency range audible to humans?

Humans can hear sound frequencies approximately between 20 Hz and 20,000 Hz. Signup and view all the answers

How is an echo produced?

An echo is produced by the reflection of sound waves off a surface. Signup and view all the answers

Why does the speed of sound vary in different media?

The speed of sound varies due to differences in particle density and elasticity in solids, liquids, and gases. Signup and view all the answers

What are the applications of ultrasound?

Ultrasound is used in medical scanning, non-destructive testing, and sonar technology. Signup and view all the answers

Study Notes

Wave Properties

Amplitude (A): Maximum displacement from the original position, measured in meters.
Wavelength (λ): Horizontal distance between two points in phase, measured in meters.
Period (T): Time for a wave to complete one cycle, measured in seconds.
Frequency (f): Number of cycles per second, measured in Hertz (Hz).
Relationship between Frequency and Period: f = 1/T
Wave Speed (v): Calculated as v = fλ (speed in m/s, frequency in Hz, wavelength in meters).
Transverse Waves: Particles vibrate perpendicular to the wave's direction of motion. Examples include electromagnetic waves, water waves, and S-seismic waves.
Longitudinal Waves: Particles vibrate parallel to the wave's direction of motion. Examples include sound waves and P-seismic waves.
Wave Phenomena: Waves exhibit reflection, refraction, and diffraction.

Reflection

Reflection: Change in direction when a wave collides with a reflective barrier. The angle of incidence equals the angle of reflection.

Refraction

Refraction: Change in direction when a wave passes through a different medium.
Refraction and Medium Changes: Refraction occurs when the wave direction isn't perpendicular to the medium boundary. The speed of the wave changes with the medium (e.g., water depth).
Deep to Shallow Water: Wave speed decreases and wavelength shortens.
Shallow to Deep Water: Wave speed increases and wavelength lengthens.

Diffraction

Diffraction: Spreading of a wave as it passes through an opening or around an edge.
Factors Affecting Diffraction: Diffraction increases with smaller gaps or larger wavelengths.

Light as a Wave

Light exhibits reflection, refraction, and diffraction; hence it is a wave.

Reflection in a Plane Mirror

Image Characteristics: Upright, virtual, laterally inverted, and same size as the object.
Image Formation: Same distance from the mirror as the object.

Refraction of Light

Refraction: Bending of light rays at the boundary of two media with different densities
Denser Medium (i > r): When light passes from a less dense medium to a denser medium, the angle of incidence is greater than the angle of refraction.
Less Dense Medium (i < r): When light passes from a denser medium to a less dense medium, the angle of incidence is less than the angle of refraction.
Snell's Law: (sin i) / (sin r) = constant (n); where n is the refractive index, which is constant for a specific medium and light. n > 1.
Refractive Index: Ratio of the speeds of a wave in two different regions. Another formula for refractive index is

Total Internal Reflection

Total Internal Reflection: Occurs when a light ray propagates from an optically denser to a less dense medium and the angle of incidence is greater than the critical angle (Note: Light ray begins from optically denser medium and incident/reflects/refracts at a boundary to a less dense medium. The angle must exceed the critical angle.). This results in complete reflection.
Critical Angle: Angle where a light ray reflects internally completely instead of passing into another medium.
Phenomena related to Total Internal Reflection & Critical Angle:
- Mirage
- Rainbow

Thin Lenses

Converging Lenses (Convex): Parallel light rays focus at a single point (principal focus, f) and produce real or virtual images.
Diverging Lenses (Concave): Parallel light rays diverge; the image is always virtual.
Ray Diagrams: Essential for analyzing image characteristics (real/virtual, enlarged/diminished, upright/inverted). Use three specific rules.
Focal Length (f): Distance from the lens to the principal focus (depends on the curvature of the lens).
Principal Axis: Imaginary line passing through the center of the lens.
Principal Focus (Focal Point): Point where parallel light rays converge or appear to diverge.

Dispersion of Light

Dispersion: Separation of white light into its constituent colours by refraction, based on varying degrees of bending for each colour.
Spectrum: Sequence of colours (red, orange, yellow, green, blue, indigo, violet) in order of decreasing wavelength (or increasing frequency).
Monochromatic Light: Light of a single frequency/wavelength.

Electromagnetic Spectrum

Electromagnetic Waves: Transverse waves consisting of electric and magnetic fields; travel at the speed of light in a vacuum (3 x 10⁸ m/s).
Frequency & Wavelength: Frequency increases and wavelength decreases as you move from radio waves to gamma rays.
Applications: Various regions of the spectrum have specific applications (radio, microwave, infrared, visible, ultraviolet, X-ray, gamma ray).
Harmful Effects of Excessive Exposure: Different parts of the electromagnetic spectrum can cause various health issues (e.g., microwaves causing internal heating).

Sound Waves

Sound Waves: Longitudinal waves requiring a medium to propagate.
Speed of Sound: Fastest in solids, then liquids, then gases.
Frequency & Pitch: Higher frequency correlates to a higher pitch.
Amplitude & Loudness: Higher amplitude correlates to a louder sound.
Human Hearing Range: 20 Hz to 20 kHz.
Ultrasound: Sound waves with frequencies above 20 kHz.
Applications: Non-destructive testing, medical scanning, sonar.
Echo: Reflection of a sound wave.

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Description

Explore the fundamental properties of waves, including amplitude, wavelength, frequency, and wave speed. This quiz also delves into the concepts of transverse and longitudinal waves, as well as key wave phenomena like reflection, refraction, and diffraction. Test your understanding of these essential physics concepts.