Optics, Waves, Electromagnetism, and AC Circuits Flashcards

Flashcards covering key concepts from lecture notes on Optics, Waves and Wave Motion, Electromagnetism and AC Circuits, Electrostatics, Capacitors, and Current Electricity.

What is light a form of?

Energy that travels in a straight line.

What are luminous objects?

Objects that produce light on their own (e.g., sun, fireworms, firefly).

What are non-luminous objects?

Objects that do not produce light on their own but reflect it from luminous objects (e.g., moon, stars).

What are opaque objects?

Objects that do not allow light to go through them (e.g., wood, wall, people).

What are transparent objects?

Objects that allow most of the light to go through them (e.g., glass, clear water, clear polythene).

What are translucent objects?

Objects that allow some light to go through them (e.g., paper, bathroom glasses, tinted glass).

What is a ray of light?

The direction of the path taken by light, indicated by a straight line with an arrow.

What is a beam of light?

A collection of light rays or a stream of light energy.

What are the three types of light beams?

Parallel, convergent, and divergent beams.

Describe a parallel beam.

Rays are parallel to each other, obtained from a distant source or searchlights.

Describe a convergent beam.

Rays from different directions meet at a common point (e.g., light behind a convex lens after passing through it).

Describe a divergent beam.

Rays start from a common point and separate into different directions (e.g., light from a torch and car lights).

What is reflection of light?

The bouncing of light as it strikes a reflecting surface.

What are the two types of reflection?

Regular reflection and irregular (diffuse) reflection.

Describe regular reflection.

An incident parallel beam is reflected as a parallel beam when light falls on a smooth surface (e.g., plane mirror, polished surfaces).

Describe irregular (diffuse) reflection.

An incident parallel beam is reflected in different directions when light falls on a rough surface (e.g., iron sheets, unclear water).

What is the angle of incidence (i)?

The angle between the normal and the incident ray.

What is the angle of reflection (r)?

The angle between the normal and the reflected ray.

State the first law of reflection.

The incident ray, the reflected ray, and the normal at the point of incidence all lie on the same plane.

State the second law of reflection.

The angle of incidence is equal to the angle of reflection (i = r).

What is the deviation (d) of light by a plane mirror for a glancing angle (g)?

d = 2g.

What is the angle (β) through which a reflected ray is rotated when a plane mirror is turned through an angle (α) with a constant incident ray?

β = 2α.

What is the net deviation (d) by successive reflection at two inclined mirrors with an angle θ between them?

d = 2θ anti-clockwise or d = (360 - 2θ) clockwise.

What is a sextant?

An instrument used for measuring the angle of elevation of heavenly bodies like stars and the sun.

How is an image formed by a plane mirror?

By the intersection of at least two rays, appearing to come from behind the mirror.

List the properties of images formed by a plane mirror.

Same distance behind the mirror as the object in front, same size as the object, erect (upright), laterally inverted, and virtual (cannot be formed on a screen).

What is a real image?

An image that can be formed on a screen and is formed by the actual intersection of light rays (e.g., images from concave mirrors and convex lenses).

What is a virtual image?

An image that cannot be formed on a screen and is formed by the apparent intersection of light rays (e.g., images from plane mirrors, concave lenses, and convex mirrors).

What is the minimum vertical length of a plane mirror for a man to see his whole self?

Half the height of the object (man).

Why do thick plane mirrors form multiple images?

Due to successive reflections between the front and silvered back surfaces.

Why are distant images formed by thick mirrors faint?

Due to energy absorbed at each reflection.

What are the disadvantages of using plane mirrors as reflectors in optical instruments?

Produce multiple images, silvering wears out, and loss of brightness.

What are curved mirrors?

Mirrors whose surfaces are obtained from a hollow transparent sphere.

What are the two types of curved mirrors?

Concave mirrors (converging) and convex mirrors (diverging).

Describe a concave (converging) mirror.

Part of a sphere whose center C is in front of its reflecting surface.

Describe a convex (diverging) mirror.

Part of a sphere whose center C is behind its reflecting surface.

Define the center of curvature (C) of a curved mirror.

The center of the sphere of which the mirror forms a part.

Define the radius of curvature (r) of a curved mirror.

The radius of the sphere of which the mirror forms a part.

Define the pole (P) of a curved mirror.

The mid-point (center) of the mirror surface.

Define the principal axis (CP) of a curved mirror.

The line that passes through the center of curvature and the pole of the mirror.

Define paraxial rays.

Rays close to the principal axis and making small angles with the mirror axis.

Define the principal focus (F) of a concave mirror.

A point on the principal axis where paraxial rays incident on the mirror and parallel to the principal axis converge after reflection. It has a real principal focus.

Define the principal focus (F) of a convex mirror.

A point on the principal axis where paraxial rays incident on the mirror and parallel to the principal axis appear to diverge from after reflection. It has a virtual principal focus.

Define the focal length (f) of a concave mirror.

The distance from the pole to the point where paraxial rays incident and parallel to the principal axis converge after reflection.

Define the focal length (f) of a convex mirror.

The distance from the pole to the point where paraxial rays incident and parallel to the principal axis appear to diverge from after reflection.

State the relationship between focal length (f) and radius of curvature (r) for a curved mirror.

r = 2f.

What is the mirror formula?

1/f = 1/v + 1/u, where u is object distance, v is image distance, and f is focal length.

What are the sign conventions for mirror formula distances?

Distances of real objects and real images are positive; virtual objects and images are negative. Focal length of concave mirrors is positive, and negative for convex mirrors.

What is linear magnification (m)?

The ratio of image height to object height, or image distance (v) to object distance (u): m = hi/ho = v/u.

What is refraction of light?

The change of direction of light propagation as it travels from one medium to another.

Why does light bend during refraction?

As a result of the change in speed as light travels from one medium to another.

State the first law of refraction.

The incident ray, the refracted ray, and the normal at the point of incidence all lie in the same plane.

State the second law of refraction (Snell's Law).

The ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant for a given pair of media (n = sin i / sin r).

What is refractive index (n)?

The ratio of the speed of light in a vacuum (c) to the speed of light in a medium (v), or the constant ratio from Snell's law.

What is the principle of reversibility of light?

The paths of light rays are reversible, meaning light can travel in either direction along the same path.

What happens when a light ray travels from a less dense medium to a denser medium?

It is refracted towards the normal, as the speed of light decreases.

What happens when a light ray travels from a denser medium to a less dense medium?

It is refracted away from the normal, as the speed of light increases.

What is lateral displacement?

The sidewise displacement of light rays when light travels from one medium to another through a parallel-sided block.

What is the formula for lateral displacement (d) in a parallel-sided block of thickness (t)?

d = t * sin(i - r) / cos(r), where i is angle of incidence and r is angle of refraction.

What is real depth and apparent depth in the context of refraction?

Real depth is the actual depth of an object, while apparent depth is the perceived depth due to refraction (n = real depth / apparent depth).

What is the formula for apparent displacement (d) of an object viewed normally through a medium?

d = t * (1 - 1/n), where t is the real depth and n is the refractive index.

What is total internal reflection?

The reflection of light within a dense medium when the angle of incidence exceeds the critical angle of the medium.

What is critical angle (C)?

The angle of incidence for which the angle of refraction is 90° for a ray of light traveling from a more optically dense medium to a less optically dense medium.

What are the conditions for total internal reflection to occur?

The ray of light must travel from a more dense medium to a less dense medium, and the angle of incidence must be greater than the critical angle.

What is the relationship between critical angle (C) and refractive index (n)?

sin C = 1/n.

List applications of total internal reflection.

Formation of mirages, rainbows, transmission in optical fibers, transmission of sky radio waves, and prism binoculars.

What is a mirage?

An optical illusion of a pool of water appearing on a hot road surface, caused by total internal reflection in heated air layers.

How do optical fibers transmit light?

Light entering the fiber strikes the boundary of the media at an angle greater than the critical angle, undergoing repeated total internal reflection.

How do prisms in binoculars use total internal reflection?

They cause lateral and vertical inversion to produce an erect image, reflecting light through 180° with minimal loss.

What is a prism (in optics)?

A geometrical object with at least two plane surfaces, made of glass, that deviates light.

What is the refracting angle (A) of a prism?

The angle between any two inclined surfaces of a prism.

Why does a prism deviate light towards its base?

Because a ray moving from a less optically dense medium bends towards the normal, and a ray moving from a more optically dense medium bends away from the normal.

What is deviation (d) by a prism?

The change in direction of a ray of light produced by a prism; the angle between the incident ray and the emergent ray.

What is the formula for deviation (d) by a prism?

d = (i1 + i2) - A, where i1 and i2 are angles of incidence and emergence, and A is the refracting angle.

When does minimum deviation occur in a prism?

When the ray of light passes symmetrically through the prism, meaning the angle of incidence (i1) equals the angle of emergence (i2), and r1 equals r2.

What is the relationship between refractive index (n), refracting angle (A), and minimum deviation (Dmin) for a prism in air?

n = sin((Dmin + A)/2) / sin(A/2).

How does deviation (D) vary with the angle of incidence (i) for a prism?

As i increases, D decreases to a minimum (Dmin) and then increases.

What is the formula for deviation (d) for a small angle prism (A ≤ 10°)?

d = (n - 1)A.

What is 'grazing property' of light rays as applied to prisms?

When the incident or emergent angle is equal to 90° to the normal of the prism.

What is dispersion of white light by a transparent medium?

The separation of white light into its component colors by a transparent medium due to their speed differences in the medium.

What is the spectrum of white light?

A mixture of various colors: red, orange, yellow, green, blue, indigo, and violet light bands.

Which color is deviated most and least upon refraction through a prism?

Violet is deviated most, while red is deviated least.

What is angular separation (angular dispersion) caused by a prism?

The difference in deviation between two wavelengths (e.g., violet and red light): φ = (nv - nr)A.

What is a spectrometer used for?

To measure accurate determination of deviation of a parallel beam of light through a prism, studying optical spectra, and measuring prism angle, minimum deviation, and refractive index.

What are the initial adjustments needed for a spectrometer?

Collimator adjusted for parallel rays, telescope adjusted for collimator light on cross-wire, and turn table leveled.

What are the uses of a glass prism?

Measure refractive index, disperse light, act as reflecting surfaces with minimal energy loss, and in prism binoculars.

What is a lens?

A piece of glass bounded by one or two spherical surfaces.

What are the two types of lenses?

Converging (convex) and diverging (concave) lenses.

Describe a converging (convex) lens.

Thicker in the middle than at the edges, curves outwards.

Describe a diverging (concave) lens.

Thinner in the middle than at the edges, curves inwards.

Define principal focus (F) of a convex lens.

A point on the principal axis where rays originally parallel and close to the principal axis converge after refraction.

Define principal focus (F) of a concave lens.

A point on the principal axis where rays originally parallel and close to the principal axis appear to diverge from after refraction.

What is the thin lens formula?

1/f = 1/u + 1/v.

What is the power of a lens (P)?

The reciprocal of the focal length in meters (P = 1/f(m)). The SI unit is Dioptres (D).

How is the power of two lenses in contact calculated?

P = P1 + P2.

What is the least distance between an object and a real image formed by a convex lens?

4f (four times the focal length).

What are conjugate points in relation to a lens?

Points on the principal axis such that if the object is at one, the image is formed at the other.

What is Newton's equation for lenses (relating object and image distances from the focal points)?

f^2 = xy, where x and y are distances of the object and image from the focal points, respectively.

What is a virtual object for a lens?

A collection of points which may be regarded as a source of light rays for a portion of an optical system but which does not actually have this function (e.g., an image from one lens acting as an object for another).

What is the full thin lens formula (lens maker's formula)?

1/f = (n - 1) * (1/r1 + 1/r2), where n is refractive index and r1, r2 are radii of curvature.