high school part 2 /2 by ssl technologies physics ex-49 click the mirror equation is a geometrical...

High School

Part 2 /2

by SSL Technologies

Physics Ex-49

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The mirror equation is a geometrical derivation for solvingproblems with curved mirrors.

Where: f = focal length (in metres) do = Object distance (in metres)

di = Image distance (in metres)

Where: M = magnification factor (no units) hi = height of image (in metres) ho = height of object (in metres)

and

PART-2 /2

Physics Ex-49

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Be sure to observe the following sign conventions when usingthe mirror formula:

All distances are measured from the vertex of a curved mirror. Distances of objects and real images are positive. Distances of virtual images are negative. Object and image heights are positive when upright and

negative when inverted.

Parabolic mirrors are used as reflectors for searchlights, flashlights,projectors and automobile headlights.

Where: f = focal length (in metres) do = Object distance (in metres)

di = Image distance (in metres)

PART-2

Physics Ex-49

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When M is less than 1,the image is reduced.

When M is negative,the image is inverted.

Physics Ex-49

Type (real or virtual): _______________

Location: _______________

Magnification: _______________

Attitude (upright/inverted): _______________

Question-1

An object is 60 cm from a converging mirror whose radius ofcurvature is 30 cm.

Determine the characteristics of the image.

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Real

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20 cm (in front of mirror)

- 0.33 (inverted and smaller than object)

Inverted

Physics Ex-49

Type (real or virtual): _______________

Location: _______________

Magnification: _______________

Attitude (upright/inverted): _______________

Question-2

An object is 25 cm from a concave mirror whose focal lengthis 15 cm. Determine the characteristics of the image.

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Real

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37.5 cm (in front of mirror)

- 1.5 (inverted and larger than object)

Inverted

Physics Ex-49

Type (real or virtual): _______________

Location: _______________

Magnification: _______________

Attitude (upright/inverted): _______________

Question-3

An object is placed 7.5 cm from a concave mirror that has a focallength of 15 cm. Determine the characteristics of the image.

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Virtual

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15 cm (behind mirror)

2 (upright and larger than object)

Upright

Negative sign indicates virtual image

Physics Ex-49Question-4

A converging mirror has a focal length of 15 cm. Where wouldyou place an object in front of this mirror in order to producean upright, virtual image, twice as tall as the object?

ClickClickNegative sign indicates

virtual image

Physics Ex-49

This means a virtual image (di is negative).

Question-5

What is the focal length of a concave mirror when an object thatis placed 2 cm in front of the mirror produces an image that isseen 5 cm behind the mirror?

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Physics Ex-49Question-6

A concave mirror has a focal length of 30 cm. A square object,4 cm per edge, is situated with its center 10 cm in front of themirror. Determine:

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a) The position (center) of the image.

Physics Ex-49Question-6

A concave mirror has a focal length of 30 cm. A square object,4 cm per edge, is situated with its center 10 cm in front of themirror. Determine:

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b) The area of the image.

Physics Ex-49Question-7

Illustrated below is an object situated in front of a convex mirror.Graphically, find the image and state its characteristics. .

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The image is virtual, upright, reduced and located behind the mirror.

NOTEConvex mirrors always produceimages that are virtual, upright

and reduced.

Physics Ex-49Question-8

An object is placed 10 cm in front of a convex mirror whosefocal length is 15 cm.

Determine the characteristics of the image.

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The image is virtual (since di is negative), upright (since M is positive),smaller than the object (since M = 0.6) and located behind themirror. Click

d i

Physics Ex-49Question-9

When an object is 30 cm in front of a concave mirror, its imageis real and situated 15 cm from the mirror.

Determine the location of the image when the object is placed 6.0 cm from the mirror.

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The image is virtual and located behind mirror.

Physics Ex-49Question-10

Fill in the four (4) missing quantities in the table below:

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MIRRORTYPE

FOCALLENGTH

OBJECTDISTANCE

IMAGEDISTANCE

OBJECTHEIGHT

IMAGEHEIGHT

Concave 4 cm -12 cm 2 cm

Convex 10 cm -7 cm 1 cm

3 cm 8 cm

-23.3 cm 0.7 cm

1 2

3 4

Physics Ex-49Question-11

An object is placed in front of a convex mirror as illustrated below.

Draw and label the light rays necessary to locate the image.

Incident ray

Reflected ray

Extended ray

Incident ray

Reflected ray

Extended ray

Image

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Image is virtual, upright and reduced.

Physics Ex-49

A) 10.0 cm

B) 20.0 cm

C) 60.0 cm

D) 90.0 cm

E) 120.0 cm

Question-12

An object 45.0 cm high is placed in front of a convex mirror whosefocal length is 30.0 cm.

If a virtual image 15.0 cm high is formed, determine the distancethe object is from the mirror.

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Step-2 Calculate do

GivenStep-1 Calculate di

REMINDER

Convex mirrors have a negative focal length.

Virtual images have a negative distance.

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