Transcript
By:
Mr. Kholipin (Pak ipin)
What is he doing? How the formation
of image on the plane mirror?
Look at picture beside, Is it
true?
Rays from object O become divergent after reflection.
How a plane mirror forms an image
mirror
O
• I is a virtual image.– cannot be picked up on a screen
Reflected rays appear to come from I behind the mirror.
mirror
O
3 How a plane mirror forms an image
I
Real and virtual image on mirrorReal and virtual image on mirror
Real ImageReal Image•formed by actual rays of converging lightformed by actual rays of converging light
•cannot be picked up on a screen
Virtual ImageVirtual Image•not formed by actual rays of not formed by actual rays of converging light, but from where the converging light, but from where the rays of light appear to come rays of light appear to come (diverging light rays)(diverging light rays)•can be picked up on a screen
• by geometric construction
O I
virtual rays shown by dotted lines
Locating the position of the imageLocating the position of the image
How a plane mirror forms an image
• OI⊥MN
N
M
• ON = NI
O IThe ray diagram shows that
Locating the position of the Locating the position of the imageimage
How a plane mirror forms an image
3 virtual
1 behind the mirror
2 of same size as the object
4 laterally inverted
How a plane mirror forms an image
Properties of the image formed by a plane mirror
mirror
object
Fimage
ExampleA girl can just see her feet at the bottom edge of the mirror.
Her eyes are 10 cm below the top of her head.
150 cm
150 cm
(a) What is the distance between the girl and her image in the mirror?
Example(a) Image distance
= Distance = 150 2 = 300 cm
Object distance
Example(b) How high above the floor is the
bottom edge of the mirror?
h1
2
h1
2
Example(b) How high above the floor is the
bottom edge of the mirror?By laws of reflection, 1 = 2
= 70 cm
The bottom edge of the mirror is 70 cm above the floor.
h = 140
12
Example 2
(c) What is the minimum height of the top edge of the mirror if she is able to see the top of her head?
(c) What is the minimum height of the top edge of the mirror if she is able to see the top of her head?
Example 2
3
4
h1
2
10 cma
b
By laws of reflection, 3 = 4
= 5 cm
Minimum height of top edge of the mirror
b = a = 1012
= b + 70
=75 cm above the floor
140 cm
So, minimum height of plane mirror in order to we can see all of our body is:
hmin=1/2*H
Where:
hmin = minimum height of plane mirror
H=height of body
The object between two plane mirrors
n = number image
α = the angle of both mirrors
α
Q1 Which of the following…Which of the following descriptions about the image formed by a plane mirror is INCORRECT ?
A Light rays come from the image to our eyes.
B The image cannot be projected on a screen.
C It is as far away from mirror as the object is in front.
D It is virtual.
Q2 Leon and Partick look in a...Leon and Patrick look in a plane mirror placed directly in front of Leon.Can they see themselves and each other in the mirror?
Leon can see himself but Patrick cannot. Both of
them can see each other
Q3 True or false: If the boy...
True or false: If the boy walks closer to the plane mirror, the image position of the candle will change.
(T/F)
Q4 A boy of height 1.5 m stands...
A boy of height 1.5 m stands 5 m in front of a plane mirror.
His image is ______ m tall and ______ m from him.
1.5 10
Q5 The ray diagram shows the...The ray diagram shows the extension of one of the reflected rays.Locate the image by completing the ray diagram.
Q6 Jenny views herself in a...Jenny views herself in a full-length mirror.
(a) Construct lines from the images of Jenny’s feet and top of her head to her eyes.
Q6 Jenny views herself in a...Jenny views herself in a full-length mirror.
(b) Mark on the mirror to indicate minimum region Jenny uses to see her full image.
Q6 Jenny views herself in a...
(c) Does this region of the mirror depend on Jenny’s distance from the mirror? (Yes/No)
Jenny views herself in a full-length mirror.
Do exercise below!
1. Paint the results of image of the object!
2. A man who has a height 180 cm standing in front of a plane mirror. If the distancebetween his eyes and top head are 12 cm. How high is the minimum mirror for he could see the whole body image in the mirror!
3. An object placed between two a plane mirrors which together form a angle 300.Determine the number of image that is formed!
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