Solutions of Reflection of Light (Page No- 209) - Physics By Lakhmir Singh, Class 10 | Extra Documents, Videos & Tests for Class 10 PDF Download

Lakhmir Singh Physics Class 10 Solutions Page No:209

Question 1: An object is kept at a distance of 5 cm in front of a convex mirror of focal length 10 cm. Calculate the position and magnification of the image and state its nature.

Solution :

u = -5cm f -10cm

We know that 

The position of the image is 3.33 cm behind the convex mirror. Magnification. m= -v/u = -3.33/-5 = 0.66 The image is virtual and erect. 

Question 2: An object is placed at a distance of 10 cm from a convex mirror of focal length 5 cm.
 Draw a ray-diagram showing the formation of image.
 State two characteristics of the image formed.
 Calculate the distance of the image from mirror.

Solution :

(ii) The image formed is diminished and erect. 
(iii) u=-10cm. f = 5cm 

Question 3: An object is placed at a distance of 6 cm from a convex mirror of focal length 12 cm. Find the position and nature of the image.

Solution : u= -6cm f = 12cm. v = ?

We know that 

Image will be formed 4 cm behind the mirror.

Since the image is formed behind the convex mirror, it is virtual and erect. 

Question 4: An object placed 20 cm in front of a mirror is found to have an image 15 cm (a) in front of it, (b) behind the mirror. Find the focal length of the mirror and the kind of mirror in each case.

Solution : (a) u =-20cm, v = -15cm

We know that 

The mirror is a concave mirror.
(b) u = -20cm v = 15cm

We know that 

The mirror is a convex mirror. 

Question 5: An arrow 2.5 cm high is placed at a distance of 25 cm from a diverging mirror of focal length 20 cm. Find the nature, position and size of the image formed.

Solution : h₁ = 2.5cm.u = -25cm. f = 20cm

We know that 

The image is formed 11.1cm behind the convex mirror.

Now. 

The image is virtual. erect and 1.11cm tall. 

Question 6: A convex mirror used as a rear-view mirror in a car has a radius of curvature of 3 m. If a bus is located at a distance of 5 m from this mirror, find the position of image. What is the nature of the image ?

Solution : Ra = 3 m  u = -5m 

We knoe that

The image is formed 1.15 m behind the mirror.

The image is virtual and erect. 

Question 7: A diverging mirror of radius of curvature 40 cm forms an image which is half the height of the object. Find the object and image positions.

Solution : R = 40cm

f = R/2 = 10/2 = 20tm

Image is half the height of the object 

So. the object is placed 20 cm in front of the mirror and the image is formed 10cm behind the mirror. 

Question 8: The radius of curvature of a convex mirror used as a rear view mirror in a moving car is 2.0 m. A truck is coming from behind it at a distance of 3.5 m. Calculate (a) position, and (b) size, of the image relative to the size of the truck. What will be the nature of the image ?

Solution :

So, the image is formed 0.77m behind the mirror.

As m is positive, so image formed is virtual and erect 

Question 9: (a) Draw a diagram to represent a convex mirror. On this diagram mark principal axis, principal focus F
 and the centre of curvature C if the focal length of convex mirror is 3 cm.
 (b) An object 1 cm tall is placed 30 cm in front of a convex mirror of focal length 20 cm. Find the size and position of the image formed by the convex mirror.

Solution :

(b) h₁ = 1cm. u = -30cm f = 20cm. h₂= ?, v = ?

The image is formed 12 cm behind the mirror.

Question 10: A shop security mirror 5.0 m from certain items displayed in the shop produces one-tenth magnification.
 (a) What is the type of mirror ?
 (b) What is the radius of curvature of the mirror ?

Solution :

(a) The mirror is of convex type.
(b) u = -5cm. m = 1/10

We have