Physics: Reflection of Light

SHORT ANSWER TYPE QUESTIONS  – 1 MARKS QUESTION

PART (A) 

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

Solution 1: As ray of light falls normally on the mirror, this means that angle of incidence is 0o. Therefore light rays will be reflected back along the same path. 

2) What type of image is formed :  

(a) in a plane mirror?  

(b) on a cinema screen?  

Solution 2:

(a) Virtual image

(b) Real image  

3) What kind of mirror is required for obtaining a virtual image of the same size as the object?  

Solution 3: Plane mirror. 

4) 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 4: Lateral inversion.  

5) 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 5: 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 

6) Which property of light makes a pencil cast a shadow when it is held in front of a light source?  

Solution 6: Light travels in straight lines.  

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

Solution 7: Virtual image. 

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

Solution 8: Equal 

9) A wall reflects light and a mirror also reflects light. What difference is there in the way they reflect light ? 

Solution 9: In regular reflection, a parallel beam of incident light is reflected as a  parallel beam in one direction; while in diffuse reflection, a parallel beam of incident light is reflected in different directions.  

10) What can you see in a completely dark room? If you switch on an  electric bulb in this dark room as a light source, explain how you could now see :  

(a) the electric bulb.  

(b) a piece of white paper.  

Solution 10: When we see in a completely dark room, we are not able to see anything because there is no light in the darkroom.

(a) We can see bulbs due to the light emitted by the bulb.  

(b) We can see a piece of white paper because it reflects the light from the bulb falling on it.  

PART (B) 

11) Name the spherical mirror which has :  

(a) virtual principal focus.  

(b) real principal focus.  

Solution 11:

(a) Convex mirror  

(b) Concave mirror  

12) Out of convex mirror and concave mirror, whose focus is situated behind the mirror ? 

Solution 12: Convex mirror  

13) Find the focal length of a concave mirror whose radius of curvature is 32 cm.  

Solution 13:

Radius of curvature (R) = 32cm Focal length (f) = ?  

 We know that f = R/2  

=32/2 f = 16cm  

14) Parallel rays of light are reflected by a concave mirror to a point  called the ………… 

Solution 14: principal focus. 

15) For a convex mirror, parallel rays of light appear to diverge from a  point called the……….  

Solution 15: principle focus. 

16) Name the two types of spherical mirrors. What type of mirror is  represented by the :  

(a) backside of a shining steel spoon ?  

(b) front side of a shining steel spoon ?  

Solution 16: Two types of spherical mirrors are:

(I) Concave mirror

(ii) Convex  mirror

Type of mirror represented by the:

(a) backside of a shining steel spoon  – convex mirror

(b) front side of a shining steel spoon – concave mirror 

17) In a convex spherical mirror, reflection of light takes place at

• a flat surface
• a bent-in surface
• a bulging-out surface
• an  uneven surface  

Solution 17: a bulging-out surface  

PART (C) 

18) For what position of an object, a concave mirror forms a real image equal in size to the object ?  

Solution 18: At the center of curvature. 

19) Where should an object be placed in front of the concave mirror so as to obtain its virtual, erect, and magnified image?  

Solution 19: Between pole and focus. 

20) For which positions of the object do a concave mirror produce an  inverted, magnified and real image ?  

Solution 20: Between focus and center of curvature. 

21) If an object is placed at the focus of a concave mirror, where is the image formed?  

Solution 21: At infinity.

22) If an object is at infinity (very large distance) in front of a concave  mirror, where is the image formed?  

Solution 22: At focus. 

23) For what position of an object, a real and diminished image is formed by a concave mirror ?  

Solution 23: Beyond the center of curvature.  

24) Which kind of mirror is used in the headlights of a car ? 

Solution 24: Concave mirror is used in the headlights of a car.  

25) Explain why, a ray of light passing through the centre of curvature of a concave mirror gets reflected back along the same path.  

Solution 25: A ray of light passing through the center of curvature of a concave  mirror is reflected back along the same path because it strikes the concave  mirror at right angles to its surface due to which the angle of incidence and  angle of reflection both are 00 

26) What is the minimum number of rays required for locating the image formed by a concave mirror for an object?  

Solution 26: Minimum two rays are required for locating the image formed by a  concave mirror for an object.

27) Which mirror is used as a torch reflector  

Solution 27: Concave mirror is used for a torch reflector.  

28) Which type of mirror is used in a solar furnace? Support your answer with reason.  

Solution 28: Concave mirror is used in a solar furnace.  

29) Name the type of mirror used by dentists. How does it help? 

Solution 29: Concave mirror is used by dentists. 

30) The angle of incidence for a ray of light passing through the center of curvature of a concave mirror is :  

• 45°  
• 90°
• 0°
• 180°  

Solution 30: 0°  

31) In the concave reflector of a torch, the bulb is placed : 

• between the pole and focus of reflector
• at the focus of reflector  
• between focus and centre of curvature of reflector
• at the centre of  curvature of reflector 

Solution 31: at the focus of reflector 

PART (D) 

32) According to the “New Cartesian Sign Convention” for mirrors,  what sign has been given to the focal length of : 

(i) a concave mirror?  

(ii) a convex mirror ?  

Solution 32:

(I) Negative

(ii) Positive  

33) All the distances are measured from the ………. of a spherical mirror. 

Solution33: Pole 

34) What sign (+ve or –ve) has been given to the following on the basis of the Cartesian Sign Convention ?  

(a) Height of a real image.  

(b) Height of a virtual image.  

Solution 34:

(a) Negative.

(b) Positive. 

PART (E) 

35) Write the mirror formula. Give the meaning of each symbol which  occurs in it.  

Solution 35: 

36) Linear magnification produced by a concave mirror may be :  

1. less than 1 or equal to 1
2. more than 1 or equal to 1  
3. less than 1, more than 1 or equal to 1
4. less than 1 or more than 1 

Solution 36: less than 1, more than 1 or equal to 1

37) Magnification produced by a convex mirror is always : 

1. more than 1
2. Less than 1
3. equal to 1
4. more or less than 1  

Solution 37: less than 1 

38) Magnification produced by a plane mirror is :  

• less than one
• greater than one
• zero
• equal to one 

Solution 38: equal to one 

PART (F) 

39) What type of image/images are formed by : 

(a) a convex mirror?  

(b) a concave mirror?  

Solution 39:

(a) Virtual and erect

(b) Virtual and erect; real and inverted 

40) Which mirror has a wider field of view?  

Solution 40: Convex mirror has a wider field of view. 

41) A diverging mirror is used as a rear-view mirror. (T/F) 

Solution 41: TRUE 

42) What type of mirror could be used :  

1. as a shaving mirror?  
2. as a shop security mirror?  

Solution 42:

1. Concave mirror.
2. Convex mirror.

Credit: Class 10 Science Group

Written By: Vivek Gupta M.Sc (Physics)