Science unit 1- Optics

What is a medium?

A medium is any physical substance through which energy can be transferred

What is radiation?

Radiation is the transfer of energy without the use of a physical medium

What is a wave?

A wave is a repeating disturbance that transfers energy from one point to another without transferring matter

What is an electromagnetic wave?

An electromagnetic wave is a wave consisting of oscillating electric and magnetic fields that can travel through empty space without requiring a physical medium

What is wavelength?

Wavelength is the distance from one crest or trough to the next crest or trough in a wave pattern

What is visible light?

Visible light consists of electromagnetic waves that can be detected by the human eye

What is incandescence?

Incandescence is the production of light as a result of high temperature

What is luminescence?

Luminescence is the emission of light by a material or object that has not been heated

What is fluorescence?

Fluorescence is light emitted during exposure of a source to ultraviolet light

What is phosphorescence?

Phosphorescence is light that continues to be emitted over time even after the ultraviolet light source is removed

What is chemiluminescence?

Chemiluminescence is light produced directly by a chemical reaction without a rise in temperature

What is bioluminescence?

Bioluminescence is light produced by a biochemical reaction within a living organism

What is reflection?

Reflection is the change in direction of a light ray when it bounces off a surface

What is a ray?

A ray is a straight line with an arrow representing the path taken by light energy

What is an incident ray?

An incident ray is a ray of light coming toward a surface

What is a reflected ray?

A reflected ray is a ray of light leaving a surface starting at the point of contact

What is a normal line?

A normal line is a perpendicular line drawn from the point of contact of the incident ray at a surface

What is the angle of incidence?

The angle of incidence is the angle measured between the incident ray and the normal line

What is the angle of reflection?

The angle of reflection is the angle measured between the reflected ray and the normal line

What are the primary characteristics of light?

Light is a form of energy that behaves as an electromagnetic wave, travels in straight lines at 3.00 times 10 to the power of 8 meters per second in a vacuum, and does not require a medium

What is the order of the electromagnetic spectrum in decreasing energy?

The order from highest energy to lowest energy is gamma rays, X rays, ultraviolet light, violet, blue, green, yellow, orange, red light, infrared light, microwaves, and radio waves

How do natural and artificial light sources differ?

A natural light source generates light through natural processes like the Sun or fireflies, whereas an artificial light source is human made like incandescent bulbs or streetlights

How do atoms within light sources produce light?

Atoms absorb external energy causing electrons to jump to a higher excited state orbital, and when the electrons return to their ground state they release the excess energy as photons of light

How does a fluorescent light bulb work?

Electric current charges electrodes that discharge electrons to collide with mercury gas atoms releasing ultraviolet light, which is then absorbed by the inner phosphor coating to emit visible light

What are the Laws of Reflection?

The incident ray, reflected ray, and normal all lie on the same plane, and the angle of incidence is equal to the angle of reflection

What is an image?

An image is a reproduction of an object produced by an optical device such as a mirror or lens

What is a real image?

A real image is formed when light rays actually converge and meet at the image location

What is a virtual image?

A virtual image is an image in which light rays do not actually meet at the image location but only appear to come from it

What is a plane mirror?

A plane mirror is any mirror that has a flat reflective surface

What is a concave mirror?

A concave mirror is a mirror whose reflective surface curves inward like the inside of a bowl

What is a convex mirror?

A convex mirror is a mirror whose reflective surface curves outward like the exterior of a sphere

What is the centre of curvature?

The centre of curvature C is the centre of the sphere whose surface was used to construct a curved mirror

What is the principal axis?

The principal axis is a line passing through the centre of curvature and the midpoint vertex of a mirror or lens

What is the vertex?

The vertex V is the point where the principal axis meets the surface of a curved mirror

What is the focus or focal point?

The focus F is the point on the principal axis where parallel incident rays converge or appear to diverge upon reflection

What is focal length?

Focal length f is the distance along the principal axis from the vertex to the focus

What are the four general characteristics of images in LOST?

The four characteristics are Location, Orientation, Size, and Type

How do you draw a ray diagram for an object in a plane mirror?

Draw a perpendicular ray that reflects back along itself and extend it behind using a dashed line, then draw a second ray at an angle reflecting at an equal angle and extend it behind until the dashed lines intersect

What are the characteristics of object image lines for a plane mirror?

Object image lines connecting corresponding points on an object and its image are perpendicular to the mirror surface and bisected by it into equal lengths

How do you locate a plane mirror image using equal perpendicular lines?

Draw construction lines perpendicular to the mirror surface from object points, measure the distance to the mirror, and extend that exact distance behind the mirror to plot image points

What are the characteristics of images in plane mirrors?

Plane mirror images are located the same distance behind the mirror, upright but laterally inverted, the same size as the object, and virtual

How do concave and convex mirrors affect parallel light rays?

Concave mirrors converge parallel incident rays at the focus, whereas convex mirrors diverge parallel incident rays as if coming from the focus behind

What is the relationship between focal length and centre of curvature?

The focal length f is equal to one half of the distance from the vertex to the centre of curvature C

What are the ray rules for concave and convex mirrors?

For concave mirrors a parallel ray reflects through F, a ray through F reflects parallel, and a ray through C reflects back on itself, while for convex mirrors rays reflect as if diverging from F or C behind the mirror

How do you use a ray diagram to find an image in a curved mirror?

Draw incident rays from the top of the object following ray rules, reflect them, and locate the image where reflected rays physically cross or where dashed extensions meet

What are image characteristics in a concave mirror when object is between F and mirror?

The image is located behind the mirror, upright, larger than the object, and virtual

What are image characteristics in a concave mirror when object is between F and C?

The image is located in front of the mirror beyond C, vertically inverted, larger than the object, and real

What are image characteristics in a concave mirror when object is beyond C?

The image is located in front of the mirror between C and F, vertically inverted, smaller than the object, and real

What happens when an object is located at the focus of a concave mirror?

No image is formed because the reflected light rays are completely parallel and never intersect

What are image characteristics in a concave mirror when object is at C?

The image is located in front of the mirror at C, vertically inverted, the same size as the object, and real

What are the image characteristics in convex mirrors?

Images in convex mirrors are always located behind the mirror between the vertex and focus, upright, smaller than the object, and virtual

How do you solve problems using mirror and magnification equations?

Use 1/f equals 1/di plus 1/do and m equals hi over ho which equals negative di over do, setting negative di for virtual images, negative f for convex mirrors, and negative hi for inverted images

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What is refraction?

Refraction is the bending or change in direction of light when it passes obliquely from one medium into another due to a speed change

What is a refracted ray?

A refracted ray is the ray of light that has crossed the boundary into a second medium and travels in a new direction

What is the angle of refraction?

The angle of refraction is the angle measured between the normal line and the refracted ray inside the second medium

What is the index of refraction?

The index of refraction n is the ratio of the speed of light in a vacuum c to the speed of light in a given medium v given by formula n equals c over v

What is dispersion?

Dispersion is the separation of white light into its component spectral colors through refraction

What is partial reflection and refraction?

Partial reflection and refraction is a phenomenon where part of incident light reflects off a boundary while the rest refracts into the new medium

What is the critical angle?

The critical angle is the angle of incidence in a denser medium that produces an angle of refraction of 90 degrees along the surface boundary

What is total internal reflection?

Total internal reflection is the complete reflection of light back into the original denser medium when the angle of incidence exceeds the critical angle

What is a mirage?

A mirage is an optical illusion produced by the refraction of sky light passing through air layers of extreme temperature differences and varying densities near hot ground

What is a lens?

A lens is a transparent object with at least one curved side that causes light to refract

What is the axis of symmetry of a lens?

The axis of symmetry is a vertical line that divides a lens into two congruent symmetrical halves

What two characteristics of light change when it refracts?

Both the speed and the direction of light change when it enters a new medium at an angle

What is Fermat's Principle?

Fermat's Principle states that when light travels from one point to another it follows the path that requires the least amount of time

Why does light change direction according to Fermat's Principle?

Light bends across media boundaries to minimize total travel time by taking a longer distance through the faster medium and a shorter path through the slower medium

How do light rays bend entering slower versus faster media?

Light rays bend toward the normal line when entering a slower medium and bend away from the normal line when entering a faster medium

Why does dispersion occur?

Dispersion occurs because shorter wavelengths like violet slow down more and refract at greater angles than longer wavelengths like red when entering a medium

How do you calculate light speed in a medium using index of refraction?

Use formula v equals c over v rearranged to v equals c over n where c is 3.00 times 10 to the power of 8 meters per second and n is the index of refraction

When and how does total internal reflection occur?

Total internal reflection occurs when light travels from a slower to a faster medium and the angle of incidence is strictly greater than the critical angle

How does a rainbow form and why is red seen at the top?

Sunlight refracts, disperses, internally reflects, and refracts exiting raindrops, and since red light exits at lower angles relative to the horizon, red light entering our eyes comes from droplets higher in the sky

How does a mirage form?

Hot ground heats air near the surface, causing sky light traveling down to speed up and refract upward, and the brain projects this light straight down onto the ground as a water reflection

What are characteristics of converging and diverging lenses?

Converging lenses are thicker in the middle and bring parallel rays together at a focus, whereas diverging lenses are thinner in the middle and spread parallel rays apart

How do you identify whether a lens is converging or diverging from a diagram?

A lens thicker at the center than at its top and bottom edges is converging, while a lens thinner at the center than at its edges is diverging

Why does a lens have two focal points on the principal axis?

A lens has two focal points because light can enter and pass through the transparent lens from either direction

What factors determine the position of the focal point of a lens?

The position is determined by the curvature of the lens surface and the index of refraction of the lens material

What are ray rules for converging and diverging lenses?

Converging rules: parallel ray refracts through far focus F, central ray passes unbent, and ray through near focus F prime refracts parallel. Diverging rules: parallel ray refracts as if from near focus F, central ray passes unbent, and ray toward far focus F prime refracts parallel

How do you use a ray diagram to find an image in a lens?

Draw incident rays from the top of the object to the axis of symmetry, refract them according to lens ray rules, and mark the image point where rays intersect or dashed extensions meet

What are image characteristics in a converging lens when object is between F and lens?

The image is located on the same side behind the object, upright, larger than the object, and virtual

What are image characteristics in a converging lens when object is between F and 2F?

The image is located on the opposite side beyond 2F, vertically inverted, larger than the object, and real

What are image characteristics in a converging lens when object is beyond 2F?

The image is located on the opposite side between F and 2F, vertically inverted, smaller than the object, and real

What are the image characteristics in diverging lenses?

Diverging lens images are always located on the same side closer to the lens, upright, smaller than the object, and virtual

Which equations are used for lens and refraction calculations?

Use Snell's Law n1 sin theta1 equals n2 sin theta2 for refraction angles, thin lens equation 1/f equals 1/di plus 1/do, and magnification equation m equals hi over ho which equals negative di over do