Physics Class: Light - Reflection and Refraction
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Questions and Answers

What type of lens is described if its power is -2.0 D?

  • Cylindrical lens
  • Concave lens (correct)
  • Bifocal lens
  • Convex lens

If an object 5 cm tall is placed 25 cm from a converging lens with a focal length of 10 cm, what is the nature of the image formed?

  • Real and inverted (correct)
  • Virtual and inverted
  • Real and upright
  • Virtual and upright

How far is an object placed from a concave lens if it forms an image 10 cm from the lens, if the lens has a focal length of 15 cm?

  • 15 cm
  • 20 cm
  • 5 cm
  • 30 cm (correct)

What size and nature of the image is formed when an object of height 5 cm is placed 20 cm in front of a convex mirror with a radius of curvature of 30 cm?

<p>3.0 cm, virtual (B)</p> Signup and view all the answers

What happens to light when it moves from one transparent medium to another?

<p>It changes its direction. (A)</p> Signup and view all the answers

What is the focal length of a convex mirror with a radius of curvature of 32 cm?

<p>16 cm (A)</p> Signup and view all the answers

What observation suggests that the bottom of a pond appears raised?

<p>Light bends as it enters a different medium. (B)</p> Signup and view all the answers

When a pencil is half immersed in water, what contributes to the illusion of it being displaced?

<p>Different angles of light create a visual effect. (C)</p> Signup and view all the answers

Which liquid would likely show a different extent of displacement for a pencil submerged in it?

<p>Kerosene (D)</p> Signup and view all the answers

What happens to the appearance of letters when viewed through a glass slab?

<p>They appear raised. (C)</p> Signup and view all the answers

Which of the following can be a consequence of light traveling through different media?

<p>Direction of light can change. (D)</p> Signup and view all the answers

If a concave mirror produces a three-times magnified real image of an object placed at 10 cm, where is the image located?

<p>At 30 cm from the mirror. (D)</p> Signup and view all the answers

What happens to paper when sunlight is converged by a concave mirror?

<p>It ignites and may catch fire. (B)</p> Signup and view all the answers

What is the point at which reflected rays from a concave mirror intersect called?

<p>The principal focus (B)</p> Signup and view all the answers

What is the nature of the image formed by a convex lens when the object is placed at infinity?

<p>Real and inverted (D)</p> Signup and view all the answers

What is the role of the principal axis in relation to a concave mirror?

<p>It is the axis normal to the mirror's surface. (C)</p> Signup and view all the answers

Where is the image formed when the object is placed between F1 and 2F1 in a convex lens setup?

<p>Between F2 and 2F2 (A)</p> Signup and view all the answers

How is the focal length of a concave mirror approximately determined?

<p>By locating the spot where light converges on a paper. (D)</p> Signup and view all the answers

What happens to the size of the image when the object is moved further away from a concave lens?

<p>The image size decreases (C)</p> Signup and view all the answers

What is the main reason for the burning of paper when using a concave mirror to concentrate sunlight?

<p>The concentrated light generates heat. (C)</p> Signup and view all the answers

When an object is placed at 2F1 in front of a convex lens, what is the relative size of the image formed?

<p>Same size (C)</p> Signup and view all the answers

What is indicated if a concave mirror reflects rays of light that are parallel to the principal axis?

<p>They converge at the focal point. (B)</p> Signup and view all the answers

What type of image is formed by a concave lens when observing an object such as a candle?

<p>Virtual and erect (D)</p> Signup and view all the answers

What can be inferred if the bright spot of light appears closer to the mirror than expected?

<p>The focal length is shorter than measured. (A)</p> Signup and view all the answers

If an object is placed at the focus F1 of a convex lens, what occurs to the size of the image?

<p>The image becomes infinitely large (C)</p> Signup and view all the answers

What would happen if a convex mirror was used instead of a concave mirror in the same setup with sunlight?

<p>Light would diverge and spread out. (B)</p> Signup and view all the answers

For an object placed beyond 2F1 of a convex lens, what is the nature of the image formed?

<p>Real and inverted (A)</p> Signup and view all the answers

When observing through a concave lens, what is the position of the image compared to the object?

<p>On the same side of the lens as the object (B)</p> Signup and view all the answers

What does the lens formula relate?

<p>Object distance, image distance, and focal length (D)</p> Signup and view all the answers

Given a concave lens with a focal length of -15 cm, what is the sign of the image distance when forming a virtual image?

<p>Negative (D)</p> Signup and view all the answers

How is the magnification 'm' calculated using object distance 'u' and image distance 'v'?

<p>m = v / u (A)</p> Signup and view all the answers

If an object is placed 30 cm to the left of a concave lens producing a virtual image at -10 cm, what is the correct object distance 'u'?

<p>-30 cm (C)</p> Signup and view all the answers

What type of image does a concave lens always form?

<p>Virtual and erect (B)</p> Signup and view all the answers

What does a positive magnification value indicate about an image?

<p>The image is virtual and erect (D)</p> Signup and view all the answers

What is the magnification produced by an image distance of -10 cm and an object distance of -30 cm?

<p>0.33 (D)</p> Signup and view all the answers

Why must care be taken with the signs of different quantities in lens calculations?

<p>To comply with common conventions in physics (C)</p> Signup and view all the answers

What does 1 dioptre of the power of a lens represent?

<p>The reciprocal of the focal length in meters (D)</p> Signup and view all the answers

Where is the needle placed in front of a convex lens if the image formed is real, inverted, and equal in size to the object, given that the image distance is 50 cm?

<p>100 cm from the lens (A)</p> Signup and view all the answers

What is the power of a concave lens with a focal length of 2 meters?

<p>-2 dioptres (A)</p> Signup and view all the answers

What does the magnification produced by a spherical mirror represent?

<p>The ratio of the height of the image to the height of the object (B)</p> Signup and view all the answers

When light travels from a denser medium to a rarer medium, how does it behave?

<p>Bends away from the normal (C)</p> Signup and view all the answers

What determines the refractive index of a medium?

<p>The ratio of the speed of light in vacuum to that in the medium (D)</p> Signup and view all the answers

What is the relationship between the focal length of a spherical mirror and its radius of curvature?

<p>Focal length is equal to half the radius of curvature (C)</p> Signup and view all the answers

What occurs at both air-glass and glass-air interfaces in a rectangular glass slab?

<p>Refraction takes place at both interfaces (A)</p> Signup and view all the answers

Flashcards

Principal Axis

An imaginary line passing through the center of a spherical mirror and perpendicular to its reflecting surface.

Concave Mirror

A spherical mirror with a reflecting surface that curves inward.

Focus (concave mirror)

The point where parallel rays of light converge after reflection from a concave mirror.

Focal Length

The distance between the focus and the center of a concave mirror.

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Principal Focus

The focus of a concave mirror where parallel rays converge after reflection.

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Convex Mirror

A spherical mirror with a reflecting surface that curves outward.

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Image of the sun

A point of light created when sunlight is reflected to converge at the focus of a concave mirror.

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Activity 10.2

An experiment to observe light concentration using a concave mirror and a piece of paper.

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Magnification (m)

The ratio of the height of the image (h') to the height of the object (h). It also equals the negative ratio of image distance (v) to object distance (u).

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Radius of Curvature

The distance from the center of curvature to the mirror.

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Refraction

The change in direction of light as it passes from one transparent medium to another.

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Apparent Displacement

The perceived shift in the position of an object due to light refracting as it enters a different medium.

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Transparent Medium

A material that allows light to pass through it.

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Lens Formula

An equation that relates the object distance (u), image distance (v), and focal length (f) of a lens. It states that 1/v - 1/u = 1/f.

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Sign Convention for Lenses

A set of rules for assigning positive or negative values to object distance (u), image distance (v), and focal length (f) in lens calculations. Distances measured in the direction of incident light are positive, while distances measured against the direction of incident light are negative.

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Convex Lens: Image at Infinity

When an object is placed at infinity, a convex lens forms a real, inverted, and highly diminished image at the focal point F2.

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Magnification (Lens)

The ratio of the height of the image (h') to the height of the object (h). It is also equal to the ratio of the image distance (v) to the object distance (u) (m = h'/h = v/u).

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Convex Lens: Object Beyond 2F1

An object beyond 2F1 of a convex lens creates a real, inverted, and diminished image between F2 and 2F2.

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Convex Lens: Object at 2F1

When an object is placed at 2F1 of a convex lens, the image is real, inverted, and the same size, formed at 2F2.

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How to determine the Magnification sign?

A positive magnification indicates an upright (virtual) image, and a negative magnification indicates an inverted (real) image.

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Concave Lens Properties

A concave lens always produces a virtual, erect, and diminished image on the same side as the object.

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Convex Lens: Object Between F1 and 2F1

Placing an object between F1 and 2F1 of a convex lens results in a real, inverted, and magnified image beyond 2F2.

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Object distance (u)

The distance between the object and the lens.

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Convex Lens: Object at F1

When an object is at F1 of a convex lens, the image formed is real, inverted, and infinitely large at infinity.

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Convex Lens: Object Between F1 and O

An object placed between the focal point F1 and the optical center O of a convex lens forms a virtual, upright, and magnified image on the same side as the object.

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Image distance (v)

The distance between the lens and the image.

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Focal length (f)

The distance between the lens and its focal point.

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Concave Lens: Image Formation

A concave lens always forms a virtual, upright, and diminished image, regardless of the object's position.

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Moving Object Away from Lens

As an object moves further away from a lens, the size of the image generally decreases. This applies to both convex and concave lenses but is more pronounced with a convex lens.

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Dioptre

A unit of measurement for the power of a lens. A lens with a power of 1 dioptre converges or diverges light by 1 meter.

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Image Size & Object Size

When the image is the same size as the object, the object is placed at twice the focal length of the lens.

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Lens Power

The ability of a lens to converge or diverge light rays. It is calculated as the reciprocal of the focal length (in meters) of the lens.

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Concave Lens Power

A concave lens has negative power because it diverges light, causing the focal length to be negative.

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Mirror Formula

A formula that relates the object distance (u), image distance (v), and focal length (f) of a spherical mirror: 1/u + 1/v = 1/f

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Focal Length and Radius of Curvature

The focal length of a spherical mirror is half its radius of curvature.

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Magnification

A measure of how much an image is enlarged or reduced compared to the object. Calculated as the ratio of image height to object height.

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Refractive Index

A measure of how much light bends as it passes from one medium to another. It's the ratio of the speed of light in a vacuum to the speed of light in the medium.

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What happens when half a convex lens is covered?

A convex lens will still produce a complete image of the object even if half of it is covered with black paper. The uncovered part of the lens will still refract the light rays from the object to form a complete image, though it may be dimmer.

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Ray Diagram: Converging lens

A ray diagram for a converging lens shows how light rays from an object are refracted by the lens to form an image. The diagram includes parallel rays, rays passing through the center of the lens, and rays passing through the focal point.

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Focal Length & Power

The focal length of a lens is inversely proportional to its power. A lens with a shorter focal length has a higher power and vice versa.

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Study Notes

Light - Reflection and Refraction

  • Light travels in straight lines in a uniform medium
  • Things become visible when light is reflected off them and received by the eyes
  • Reflection is the bouncing of light off a surface
  • Reflection obeys the laws of reflection: -The angle of incidence is equal to the angle of reflection. -The incident ray, the normal to the mirror at the point of incidence, and the reflected ray all lie in the same plane.
  • Spherical mirrors are mirrors with curved surfaces, either concave or convex.

Spherical Mirrors

  • Concave -Reflecting surface curves inwards -Focuses light -Forms real or virtual images; erect or inverted, depending on the position of the object -Used in torches, headlights, and shaving mirrors
  • Convex -Reflecting surface curves outwards -Diverges light -Forms only virtual, erect and diminished images -Used in rearview mirrors

Image Formation by Spherical Mirrors

  • Object position affects the nature, position, and size of the image -Table of image position, nature and size for both Concave and Convex mirrors
  • Ray diagrams are used to show image formation
  • Key rays are used to construct ray diagrams: -A ray parallel to the principal axis, after reflection, will pass through the principal focus (or appear to diverge from it) -A ray passing through the centre of curvature is reflected back along the same path -A ray passing through the principal focus, after reflection, will emerge parallel to the principal axis

Refraction of Light

  • Light bends when it passes from one transparent medium to another. This is called refraction
  • Refraction happens because light travels at different speeds in different media
  • Refractive index relates speed of light in a vacuum to its speed in a medium; larger refractive index means light travels slower in that medium.

Refraction through a Rectangular Glass Slab

  • Light ray bends as it enters and exits the slab; emerges parallel to the original ray, but offset.

Lenses

  • Transparent material with at least one curved surface
  • Converging (convex) focused light rays - images can be real or virtual
  • Diverging (concave) spread light rays - only virtual images

Image Formation by Lenses

  • Position of the object affects the characteristics of the image formed
    • Table depicting image characteristics for various object positions for both Concave and Convex
  • Ray diagrams are used to show image formation
  • Key rays used to construct ray diagrams: -A ray parallel to the principal axis, after refraction, passes through (or appears to diverge from) the focus -A ray passing through the optical centre passes undeflected -A ray passing through the focal point emerges parallel to the principal axis
  • Magnification = image height / object height = image distance / object distance

Power of a Lens

  • Power is the reciprocal of the focal length (measured in diopters)
  • Convex lenses have positive power
  • Concave lenses have negative power

Sign Conventions

  • Coordinate system for object and image distances is used
  • Distances to the right of the optical centre are positive
  • Distances to the left are negative
  • Distances above the principal axis are positive
  • Distances below are negative

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Chapter 10 Light - Reflection and Refraction PDF

Description

This quiz covers the concepts of light reflection and refraction, specifically focusing on spherical mirrors. Learn about the laws of reflection, properties of concave and convex mirrors, and how images are formed. Test your understanding and application of these principles in real-world scenarios.

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