2C3 Waves and Optics Flashcards
Explain the nature and types of waves, focusing on how light and sound are transmitted and modified.
What is light?
A form of electromagnetic radiation with oscillating electric and magnetic fields.
Light behaves both as a wave and as particles (photons), depending on the context.
What are the two components of light waves?
- Electric fields
- Magnetic fields
These fields oscillate perpendicularly to each other and to the direction of wave propagation.
What is the speed of light in a vacuum?
Approximately 3.00 × 10⁸ m/s.
This value is equivalent 186,000 mi/s. This speed is a fundamental constant in physics, denoted by the symbol c.
True or False:
Light requires a medium to propagate.
False
Unlike sound waves, which need a material medium (air, water, or solids), light can travel through the vacuum of space due to its oscillating electric and magnetic fields, which sustain each other.
Fill in the blank:
______ exhibits both wave and particle properties.
Light
This duality is a cornerstone of quantum mechanics.
What is a photon?
A quantum, or particle, of light energy.
They are massless particles that carry energy proportional to their frequency.
What is a wavelength?
The distance between two consecutive peaks or troughs of a wave.
Wavelength is typically denoted by the symbol λ (lambda) and is measured in units of length, such as meters or nanometers.
What equation relates the energy of a photon to its frequency?
E = h x f
Here, E is energy, h is Planck’s constant (6.26x10^-34^), and f is the frequency.
What is the visible spectrum?
The portion of the electromagnetic spectrum visible to the human eye.
It ranges from approximately 380 nm (violet) to 700 nm (red).
True or False:
The electromagnetic spectrum includes only visible light.
False
It includes gamma rays, X-rays, ultraviolet light, visible light, infrared light, microwaves, and radio waves.
What determines the color of visible light?
The wavelength of the light.
Shorter wavelengths correspond to violet and blue, while longer wavelengths correspond to red.
Fill in the blank:
The ________ spectrum encompasses all types of electromagnetic radiation.
electromagnetic
The electromagnetic spectrum includes all forms of electromagnetic radiation, classified by their wavelength and frequency, from low-energy radio waves to high-energy gamma rays.
What is the order of colors in the visible spectrum from longest to shortest wavelength?
- Red
- Orange
- Yellow
- Green
- Blue
- Indigo
- Violet
This sequence can be remembered using the acronym ROYGBIV. Each color corresponds to a specific range of wavelengths within the visible spectrum.
Which color has the shortest wavelength in the visible spectrum?
Violet
Violet light has the shortest wavelength in the visible spectrum, typically around 380–450 nm.
Which color has the longest wavelength in the visible spectrum?
Red
Red light has wavelengths around 620-750 nm.
What are ultraviolet rays?
Waves with wavelengths shorter than visible light but longer than X-rays.
UV rays can cause sunburn and are blocked by sunscreen.
True or False:
Infrared radiation has a higher frequency than visible light.
False
Infrared has lower frequencies and longer wavelengths than visible light.
Fill in the blank:
________ waves have the longest wavelengths in the electromagnetic spectrum.
Radio
Radio waves can have wavelengths ranging from millimeters to kilometers.
What is the relationship between wavelength and frequency?
They are inversely proportional.
As wavelength increases, frequency decreases, and vice versa, according to the equation c = λf, where c is the speed of light, λ is the wavelength, and f is the frequency.
How does light interact with matter?
It can be reflected, absorbed, or transmitted.
These interactions depend on the material and the light’s wavelength.
True or False:
Light travels faster in glass than in air.
False
Light slows down in denser mediums like glass due to interactions with the material.
Fill in the blanks:
Transverse waves move ________ to the wave direction, while longitudinal waves move _______ to it.
perpendicular, parallel
This difference affects the types of waves, such as light being transverse and sound being longitudinal.
What are mechanical waves?
Waves that require a medium to travel through.
These waves cannot travel through a vacuum because they rely on the vibration of particles in a medium.
What are electromagnetic waves?
Waves that do not require a medium and can travel through a vacuum.
These waves consist of oscillating electric and magnetic fields and include visible light, microwaves, and X-rays.
True or False:
Mechanical waves can travel through a vacuum.
False
Mechanical waves require a medium, like air, water, or solid substances, to propagate.
What is amplitude in a wave?
The maximum distance of particles from their equilibrium position.
It determines the wave’s energy; higher amplitude waves carry more energy.
How does amplitude affect wave energy?
Higher amplitude waves carry more energy.
The energy of a wave is directly proportional to the square of its amplitude.
Fill in the blank:
Frequency in a wave is the number of complete cycles or __________ a wave makes per unit of time.
oscillations
Frequency is typically measured in hertz (Hz), where 1 Hz equals one cycle per second.
What is the period of a wave?
The time it takes for one complete cycle or oscillation.
Period is the inverse of frequency—high frequency waves have shorter periods.
How are frequency and period related?
Period is the inverse of frequency.
Period and frequency are inversely related: the period (T) is the time it takes for one complete cycle, calculated as T = 1/f, where f is the frequency.
What is wave speed?
The rate at which a wave propagates through a medium.
Wave speed depends on both the frequency and wavelength of the wave, and it can be calculated using the formula: Speed = Frequency × Wavelength.
True or False:
The wave speed is constant for all waves.
False
Wave speed varies depending on the medium through which the wave is traveling (e.g., sound travels faster in water than in air).
Fill in the blank:
If the frequency of a wave increases, the __________ decreases.
wavelength
This is due to the inverse relationship between frequency and wavelength.
What happens to the energy of a wave if its frequency increases?
It increases.
Energy is directly proportional to frequency, so higher frequency waves have more energy.
True or False:
A wave with higher frequency has lower energy.
False
Higher frequency waves, like gamma rays, carry more energy compared to lower frequency waves like radio waves.
What is the formula for calculating wave speed?
𝑣 = 𝑓𝜆
Where v is wave speed, f is frequency, and λ (lambda) is wavelength.
If a wave travels at 50 m/s and has a wavelength of 5 meters, what is its frequency?
10 Hz
The frequency is found by rearranging the formula to 𝑓 = 𝑣 / 𝜆, dividing wave speed by wavelength.
A sound wave travels at 340 m/s. If its frequency is 680 Hz, what is its wavelength?
0.5 meters
To find the wavelength, use the formula 𝜆 = 𝑣 / 𝑓, dividing the wave speed by the frequency.
What is the wavelength range for visible light?
400 nm and 700 nm.
This range is the only part of the electromagnetic spectrum visible to the human eye.
Fill in the blank:
Light wave is an example of a/an ___________ wave.
electromagnetic
Electromagnetic waves, such as light, do not require a medium and can travel through space.
True or False:
Amplitude affects the speed of the wave.
False
The speed of a wave is determined by the properties of the medium, not its amplitude.
What is reflection?
The way that light bounces when it hits a surface.
It occurs when light interacts with a boundary and does not pass through it, such as when a mirror reflects light.
What is refraction?
The bending of light as it passes from one medium to another.
Refraction occurs due to a change in the speed of light.
What is polarization of light?
The alignment of light waves in a specific direction.
For example, polarized sunglasses use this principle to block horizontally polarized light, which significantly reduces glare from reflective surfaces like water, glass, or roads, enhancing visibility and comfort.
What causes a rainbow?
Refraction, dispersion, and reflection of light in water droplets.
Different wavelengths are refracted by different amounts, separating the colors.
Fill in the blank:
________ is the splitting of white light into its constituent colors when passing through a prism.
Dispersion
Dispersion occurs because different wavelengths of light refract by different amounts.
True or False:
Violet refracts the most during dispersion.
True
Violet light has the shortest wavelength and highest refractive index, causing it to bend more than other colors.
What is total internal reflection?
Complete reflection of light within a medium above the critical angle.
This phenomenon happens only when light travels from a denser to a less dense medium, like glass to air.
What are optical fibers an example of?
Total internal reflection
Optical fibers use total internal reflection to transmit light signals over long distances without significant loss.
True or False:
Total internal reflection occurs when the angle of incidence is less than the critical angle.
False
Total internal reflection only occurs when the angle of incidence exceeds the critical angle.
Define:
Diffraction
The bending of light waves around obstacles or through small openings.
This phenomenon explains effects like the spreading of sound around corners or the patterns observed in light passing through narrow slits.
What is interference?
The interaction of two or more waves that results in a new wave pattern.
Interference can be constructive (amplifying) or destructive (canceling).
What is the principle of superposition?
When waves overlap, the resulting wave is the sum of their displacements.
This principle explains phenomena like standing waves and interference patterns.
True or False:
Destructive interference occurs when the crest of one wave overlaps with the crest of another.
False
Destructive interference occurs when a crest overlaps with a trough, canceling the wave out.
Fill in the blank:
Light waves vibrating in all directions are converted into a single plane through ________.
polarization
Polarized light is often used to reduce glare.
What type of waves can be polarized?
Transverse waves.
Only transverse waves, like light, can be polarized because their oscillations are perpendicular to wave direction.
Fill in the blank:
The process by which a material takes in light energy and converts it into heat is called ________.
absorption
Dark-colored objects absorb more light, converting it into heat energy.
What is scattering?
The redirection of light by particles in its path.
Rayleigh scattering explains why the sky appears blue, as shorter wavelengths scatter more.
What is the term for light passing through a material?
Transmission
Transparent materials like glass allow light to pass through with minimal scattering.
True or False:
Scattering only occurs in the atmosphere.
False
Scattering can occur in any medium containing particles that interact with light.
What causes the red color of sunsets?
Scattering of shorter wavelengths, leaving longer ones like red.
At sunset, sunlight passes through more atmosphere, scattering blue light away.
What is the Doppler effect?
The change in frequency or wavelength due to motion of the observer or source.
This effect is noticeable with sound, like a siren changing pitch as it passes.
What happens to the pitch of a sound as the source approaches an observer?
It increases.
According to the Doppler effect, this occurs because the sound waves are compressed, increasing their frequency.
What are three main types of of mirrors?
- Plane
- Convex
- Concave
Light interacts differently with each type of mirror.
What is a plane mirror?
A mirror with a flat surface.
These mirrors reflect light to form an image that is the same size as the object but reversed.
What is the focal point of a plane mirror?
It doesn’t have a focal point.
They reflect light without converging or diverging it, so they don’t have a real focal point.
What is a convex mirror?
A mirror with a curved surface that bulges outward.
These mirrors diverge light rays, which results in smaller, virtual, and upright images.
What is a concave mirror?
A mirror with a curved surface that curves inward like a bowl.
These mirrors can converge light rays, forming real or virtual images depending on the object’s position relative to the focal point.
True or False:
Convex mirrors always form virtual images.
True
Convex mirrors always form virtual, diminished images regardless of the object’s position.
Fill in the blank:
The focal point of a concave mirror is where the _______ rays converge.
parallel
The focal point is the point where parallel rays of light meet after being reflected by the concave mirror.
In which applications are concave mirrors generally used?
Shaving mirrors and telescopes.
Concave mirrors are used to magnify images, such as in shaving mirrors or optical telescopes for better focus on distant objects.
What is a lens?
A transparent object that refracts light to form an image.
Lenses can converge or diverge light depending on their shape (convex or concave).
What type of image is formed by a convex lens when the object is beyond the focal point?
Real and inverted.
When the object is placed beyond the focal point, a convex lens forms a real and inverted image on the opposite side of the lens.
What is a concave lens?
A lens that is thinner in the middle than at the edges.
Concave lenses diverge light rays, forming a virtual, upright, and diminished image.
True or False:
Convex lenses always form real images.
False
Convex lenses can form both real and virtual images depending on the position of the object relative to the focal point.
Fill in the blank:
______ lenses are used in microscopes.
Convex
These lenses magnify small objects by converging light and forming a magnified image.
What happens to light as it passes through a lens?
It refracts, bending toward or away from the optical axis.
The degree of refraction depends on the curvature and material of the lens, which affects the image formed.
What type of wave is sound?
Longitudinal (compression) wave.
In this kind of wave, particles move back and forth in the same direction as the wave, creating compressions and rarefactions.
What is a compression in a sound wave?
A region where particles are closest together.
It occurs when the particles of the medium are compressed, creating areas of high pressure in the sound wave.
True or False:
Sound waves can travel through a vacuum.
False
Sound requires a medium (such as air, water, or solid materials) to travel. It cannot travel through a vacuum because there are no particles to vibrate.
What is the speed of sound in air?
Approximately 343 m/s at room temperature.
The speed of sound depends on the medium (e.g., air, water, or solid materials) and temperature. It is faster in warmer air and in denser media.
What determines the pitch of a sound?
The frequency of the sound wave.
High-frequency sound waves produce high-pitched sounds, while low-frequency waves produce low-pitched sounds.
True or False:
The loudness of sound is directly related to its frequency.
False
Loudness is related to the amplitude of the sound wave, not its frequency. High amplitude means louder sound, regardless of pitch.
How is sound intensity measured?
In decibels (dB).
Decibels are a logarithmic unit used to measure sound intensity. A 10 dB increase represents a tenfold increase in intensity.
What does the human ear perceive as louder sound?
A sound with greater amplitude.
As the amplitude of a sound wave increases, the energy transferred through the medium increases, making the sound appear louder to the human ear.
Fill in the blank:
A sound with a low frequency is perceived as a ______ pitch.
low
Low-frequency sound waves produce lower-pitched sounds, such as those from a bass drum or thunder.
What is the threshold of hearing?
The quietest sound detectable, typically at 0 dB.
It corresponds to the lowest sound intensity that can be perceived, below which sound is inaudible.
What happens to the pitch of a sound as its frequency increases?
It becomes higher.
As the frequency of sound increases, the number of vibrations per second increases, leading to a higher-pitched sound.
True or False:
The Doppler effect only applies to sound waves.
False
The Doppler effect applies to all types of waves, including light waves in astronomy.
What happens to the frequency of a sound as the source moves away from the observer?
It decreases.
As the sound source moves away, the waves are stretched, decreasing the frequency and lowering the pitch.
