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# Solutions of Reflection of Light (Page No- 173) - Physics By Lakhmir Singh, Class 10 Class 10 Notes | EduRev

## Class 10 Physics Solutions By Lakhmir Singh & Manjit Kaur

Created by: Ajay Batra

## Class 10 : Solutions of Reflection of Light (Page No- 173) - Physics By Lakhmir Singh, Class 10 Class 10 Notes | EduRev

The document Solutions of Reflection of Light (Page No- 173) - Physics By Lakhmir Singh, Class 10 Class 10 Notes | EduRev is a part of the Class 10 Course Class 10 Physics Solutions By Lakhmir Singh & Manjit Kaur.
All you need of Class 10 at this link: Class 10

Lakhmir Singh Physics Class 10 Solutions Page No:173

Question 1: What happens when a ray of light falls normally (or perpendicularly) on the surface of a plane mirror ?

Solution : As ray of light falls normally on mirror, this means that angle of incidence is 0o. From second law of reflection, we know that angle of incidence is equal to angle of reflection. So, angle of reflection will also be zero. Therefore, the light ray will be reflected back along the same path.

Question 2: A ray of light is incident on a plane mirror at an angle of 30°. What is the angle of reflection ?

Solution : According to the second law of reflection, angle of incidence is equal to the angle of reflection.
Therefore, angle of reflection=300

Question 3: A ray of light strikes a plane mirror at an angle of 40° to the mirror surface. What will be the angle of reflection ?

Solution : Angle to the mirror surface = 400
Therefore, angle of incidence = 900-40= 500
According to the second law of reflection, angle of incidence is equal to the angle of reflection.
Therefore, angle of reflection = 500

Question 4: A ray of light is incident normally on a plane mirror. What will be the :
(a) angle of incidence ?
(b) angle of reflection ?

Solution :
(a) 00
(b) 00

Question 5: What type of image is formed :
(a) in a plane mirror ?
(b) on a cinema screen ?

Solution : (a) Virtual image
(b) Real image

Question 6: What kind of mirror is required for obtaining a virtual image of the same size as the object ?

Solution : Plane mirror.

Question 7: What is the name of the phenomenon in which the right side of an object appears to be the left side of the image in a plane mirror ?

Solution : Lateral inversion.

Question 8: Name the phenomenon responsible for the following effect:
When we sit in front of a plane mirror and write with our right hand, it appears in the mirror that we are writing with the left hand.

Solution : Lateral inversion.

Question 9: If an object is placed at a distance of 10 cm in from of a plane mirror, how far would it be from its image ?

Solution : The image is formed behind the mirror at the same distance as the object is kept in front of the mirror.
Given distance between object and mirror=10cm.
Distance between mirror and image=10cm.
Therefore, the distance between object and image=10+10=20cm.

Question 10: Which property of light makes a pencil cast a shadow when it is held in front of a light source ?

Solution : Light travels in straight lines.

Question 11: The image seen in a plane mirror cannot be formed on a screen. What name is given to this type of image ?

Solution : Virtual image.

Question 12: Fill in the following blank with a suitable word :

When light is reflected, the angles of incidence and reflection are…………

Solution : Equal.

Question 13: State whether the following statement is true or false :

A student says that we can see an object because light from our eyes is reflected back by the object.

Solution : False.

Question 14: Where is the image when you look at something in a mirror ?

Solution : At the back side of mirror.

Question 15: A ray of light strikes a plane mirror such that its angle of incidence is 30°. What angle does the reflected ray make with the mirror surface ?

Solution : According to the second law of reflection, angle of incidence is equal to the angle of reflection.
Given angle of incidence=300
Therefore, angle of reflection=300
Angle made by the reflected ray with mirror surface=900-300=600

Question 16: What is the difference between a real image and a virtual image ? Give one example of each type of image.

Solution : Real image can be obtained on a screen because light rays actually pass through a real image but virtual image cannot be formed on screen because light rays do not actually pass through a virtual image.
Example:-
The image formed on a cinema screen is an example of real image.
The image formed by a plane mirror is a virtual image.

Question 17: The letter F is placed in front of a plane mirror :

How would its image look like when seen in a plane mirror ?

What is the name of the phenomenon involved ?

Solution : (b) Lateral inversion

Question 18: What is lateral inversion ? Explain by giving a suitable example.

Solution : When an object is placed in front of a plane mirror, then the right side of the object appears to become the left side of the image; and the left side of the object appears to become right side of the image. This change of the sides of an object and its mirror image is called lateral inversion.
Ex. When we hold a placard having the word RED written on it, as given in fig A, in the front of a plane mirror, the image of the word RED will be as given in fig B. Question 19: Write the word AMBULANCE as it would appear when reflected in a plane mirror. Why is it sometimes written in this way (as its mirror image) on the front of an ambulance ?

Solution : Because while driving our car. If we see In our rear-view mirror that the hospital van Is coming from behind, then we wiilget the laterally  inverted  image of and read it as AMBULANCE and give way for it to pass through.

Question 20: What are the important differences between looking at a photograph of your face and looking at yourself in a plane mirror ?

Solution : A image of our face in a plane mirror is laterally inverted, so left is right and right is left. However, in a photograph of our face this is not the case.

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