Keywords To Remember
- Plane Mirror
A flat mirror that reflects light to form upright, virtual images of the same size as the object. - Image
A reproduction of an object formed by a mirror or lens through the reflection or refraction of light. - Virtual Image
An image formed by apparent intersection of reflected rays; it cannot be obtained on a screen. - Real Image
An image formed by the actual intersection of reflected or refracted rays; it can be obtained on a screen. - Lateral Inversion
The phenomenon in which the left side of an object appears as the right side in the mirror image, and vice versa. - Reflection of Light
The bouncing back of light rays when they strike a smooth and shiny surface like a mirror. - Incident Ray
The ray of light that strikes the surface of a mirror. - Reflected Ray
The ray of light that bounces off the mirror surface after hitting it. - Point of Incidence
The point on the mirror surface where the incident ray strikes. - Normal
An imaginary line drawn perpendicular to the surface of the mirror at the point of incidence. - Angle of Incidence (∠i)
The angle between the incident ray and the normal at the point of incidence. - Angle of Reflection (∠r)
The angle between the reflected ray and the normal at the point of incidence. - Laws of Reflection
- First Law: The incident ray, the reflected ray, and the normal all lie in the same plane.
- Second Law: The angle of incidence is equal to the angle of reflection.
- Plane of Incidence
The plane that contains both the incident ray and the normal. - Plane of Reflection
The plane that contains both the reflected ray and the normal. - Multiple Images
More than one image formed when two or more mirrors are placed at an angle to each other. - Kaleidoscope
A toy that shows multiple symmetrical patterns using multiple reflections in inclined mirrors. - Spherical Mirror
A mirror whose reflecting surface is a part of a sphere. There are two types:
- Concave Mirror (inward-curved surface)
- Convex Mirror (outward-curved surface)
- Concave Mirror
A spherical mirror with the reflecting surface curved inward (like the inside of a spoon); can form real or virtual images. - Convex Mirror
A spherical mirror with the reflecting surface curved outward; always forms virtual, diminished images. - Centre of Curvature (C)
The center of the sphere from which the spherical mirror is made. - Radius of Curvature (r)
The distance between the pole and the centre of curvature of a spherical mirror. - Pole (P)
The geometric center of the spherical mirror. - Principal Axis
A straight line joining the pole and the centre of curvature of a spherical mirror. - Focus (F)
The point on the principal axis where rays parallel to it either meet (concave) or appear to diverge from (convex) after reflection. - Focal Length (f)
The distance between the pole and the focus of a spherical mirror.
f = r / 2 - Ray Diagram
A diagram showing the paths of light rays to determine the position and size of an image. - Image Distance
The distance between the image and the mirror surface. - Object Distance
The distance between the object and the mirror surface. - Inverted Image
An image that is upside down compared to the object. - Erect Image
An image that appears upright compared to the object. - Diminished Image
An image smaller than the object. - Magnified Image
An image larger than the object. - Mirror Formula
An equation relating the object distance (u), image distance (v), and focal length (f) of a spherical mirror: 1\f=1/v+1/u
Something To Know
A. Fill in the blanks.
- An image, which can be obtained on a screen, is called a _________ image.
Answer – real
- The angle of reflection _________ the angle of incidence.
Answer – equals
- The incident ray, the at the point of incidence and the _________ reflected ray all lie in the same _________.
Answer – reflected, plane
- The point, where a concave mirror forms the image of a very distant object, is known as the : _________ of the mirror.
Answer – focus
- A spherical mirror, that always forms a virtual, erect and diminished image of an object, _________ is a mirror.
Answer – convex
- Eye specialists use ophthalmoscope, which is fitted with _________ mirror.
Answer – concave
B. Write True or False for the following statements.
- The image, formed by a plane mirror, shows the right side of the object as its right side and the left side of the object as its left side.
Answer – False
- When we stand between a pair of parallel plane mirrors, we can see an infinite number of images.
Answer – True
- A concave mirror can never form a virtual image of an object.
Answer – False
- We can use either a concave mirror, or a convex mirror, as the ‘reflector’ in torches.
Answer – False
- Motor vehicles generally use either a plane mirror, or a convex mirror, as their ‘rear view’ mirror.
Answer – False
C. Tick (✓) the correct option.
- The angle of incidence equals the angle between the incident ray and the—
mirror surface.
normal at the point of incidence.
reflected ray.
line inclined at 60° to the mirror surface.
Answer – normal at the point of incidence
- A ray of light, falling normally on a plane mirror, gets reflected in such a way that it—
becomes parallel to the mirror surface after reflection.
now makes an angle of 30° with the plane mirror,
now makes an angle of 60° with the plane mirror,
just retraces the path.
Answer – just retraces the path
- The central point, of the section of the sphere, used for making a spherical mirror, is known as the—
Pole of the mirror.
focus of the mirror.
centre of curvature of the mirror.
Mid point of the mirror.
Answer – centre of curvature of the mirror
- The distance, between the object and its image, in a plane mirror is 6 m. If the object moves 1 m towards the mirror, then the (new) distance between the object and its image will be—
5 m
8 m
6 m
4 m
Answer – 4 m
- The rear view mirror of a car is a plane mirror. A driver is reversing his car at a speed of 4 m/s. The driver sees, in his rear view mirror, the image of a scooter parked behind his car. The speed, at which its image appears to approach the driver, will be—
2 m/s
8 m/s
4 m/s
16 m/s
Answer – 8 m/s
D. Answer the following questions in brief.
- Explain clearly the difference between a real image and a virtual image. Give one example of a virtual image.
Answer – A real image can be formed on a screen and is inverted. A virtual image cannot be formed on a screen and is always erect.
Example: Image formed by a plane mirror is virtual.
- How does changing the distance of the object, from a convex mirror, affect the size and nature of the image formed by it?
Answer – As the object moves closer to a convex mirror, the image becomes larger but remains virtual, erect and diminished.
- Draw a ray diagram to show the formation of an image when the object is placed between the C and F points of a concave mirror.
Answer – (Ray diagram to be drawn: Object between C and F in front of a concave mirror—image formed beyond C, real and inverted.) rest part students will do.
- Where should we keep an object, in front of a concave mirror, so as to get a virtual and magnified image of it?
Answer – The object should be placed between the pole and the focus of a concave mirror to get a virtual and magnified image.
- The magnified image, of an object, appears to be formed, behind the mirror, by an apparent intersection of the reflected rays. What can you say about (a) nature of the image (b) the type of mirror used?
Answer – (a) Nature of the image: Virtual and magnified
(b) Type of mirror: Concave mirror
- Rohit suggested to his father to fix a ‘security mirror’ which would provide them with a wider view of the surrounding of their shop. Name the type of mirror that Rohit must have suggested to his father. Also mention the basic characteristics of the image formed by this type of mirrors.
Answer – Rohit must have suggested a convex mirror.
Image characteristics: Virtual, erect, diminished, and provides a wide field of view.
- State the type of mirror that the following items/objects would correspond to:
(a) inside of a stainless-steel bowl
Answer – Concave mirror
(b) reflector of a torch
Answer – Concave mirror
(c) a polished shining wooden surface
Answer – Plane mirror
(d) the shiny outer surface of the bicycle bell.
Answer – Convex mirror
E. Answer the following questions
- State the laws of reflection. Describe an activity to show that incident ray, reflected ray and the normal, at the point of incidence, all lie in same plane.
Answer – Laws of Reflection:
The angle of incidence is equal to the angle of reflection.
The incident ray, reflected ray, and the normal lie in the same plane.
Activity: Place a mirror on a white sheet with a slit source. Trace incident and reflected rays to observe they lie in the same plane.
- Trace the path of reflected ray in the following ray diagrams.
Answer – Laws of Reflection:
- The angle of incidence = angle of reflection.
- The incident ray, reflected ray, and normal all lie in the same plane.
(a) Ray is perpendicular to the mirror (i.e., angle of incidence = 0°)
➡️ Reflected ray retraces the same path back.
(b) Angle of incidence = 30°
➡️ According to the law of reflection:
Angle of reflection = 30°
➡️ Draw the reflected ray such that it makes an angle of 30° on the opposite side of the normal.
(c) Two rays from source S are hitting the mirror.
➡️ Reflect each ray using the rule: angle of incidence = angle of reflection.
➡️ After drawing the reflected rays, extend them backward. They will meet at a point behind the mirror — this gives the virtual image of point S.
(d) Angle of incidence = 45°
➡️ So, angle of reflection = 45°
➡️ Draw the reflected ray making a 45° angle with the normal on the other side. Since the mirror is at the corner, the reflected ray will bounce at 45°, then reflect again on the adjacent mirror side, again at 45°.
- Draw a ray diagram to show the formation of the image of a point object by (i) a plane mirror and (ii) a convex mirror.
Answer – 
- Three persons are standing at points P, Q and R in front of a plane mirror. Can ‘P’ see himself in the mirror? Also can he see the image of Q and R in the mirror?
Answer –
Principle:
- A person can see an object (or another person’s image) in a plane mirror only if the line of sight from the person’s eyes to the mirror can reflect the light rays coming from the object or its image.
- Light follows the law of reflection: the angle of incidence equals the angle of reflection.
Analysis of the Situation:
- The mirror is horizontal and placed in front of all three persons: P, Q, and R.
- Person P is standing to the left, and Q and R are to the right.
- The mirror is angled such that it’s in front of all three—but not all points may be in line of sight.
Can P see himself in the mirror?
- Yes, if the light rays from P reach the mirror and reflect back to his eyes.
- From the diagram, P is in front of the mirror, so he can see his own image.
Can P see Q and R in the mirror?
- For P to see Q and R’s images in the mirror:
The reflected light from Q and R’s images must reach P’s eyes.
This depends on the line of sight and positioning.
From the diagram, Q and R are not aligned in a way that their reflected images would fall into P’s line of sight in the mirror. Since plane mirrors reflect light in straight lines, and there is a significant horizontal distance between P and the others, P is not likely to see Q or R in the mirror.
Final Answer:
- Yes, P can see himself in the mirror.
- No, P cannot see the images of Q and R in the mirror.
- With the help of a suitable diagram, explain the meaning of the following terms for a concave mirror.
(a) centre of curvature
(b) pole
(c) principal axis
(d) focus
Answer – (a) Centre of Curvature – The center of the sphere of which the mirror is a part
(b) Pole – The central point of the mirror surface
(c) Principal Axis – The line passing through the pole and the centre of curvature
(d) Focus – The point where rays parallel to the principal axis converge (concave) or appear to diverge (convex)
- What type of mirror is used in the following cases? Is the image formed virtual and erect in each case?
(a) ‘make up’ mirror
(b) ‘rear view’ mirror of vehicles
(c) reflecting type telescope
(d) shaving mirror
Answer – (a) ‘Make up’ mirror – Concave, Virtual and erect
(b) ‘Rear view’ mirror – Convex, Virtual and erect
(c) Reflecting telescope – Concave, Real image
(d) Shaving mirror – Concave, Virtual and erect
Value Based Question
It was celebration time for Menons as their son had become a full fledged and registered dentist. The father advised his son to always maintain the same level of empathy, sincerity and dedication towards all his patients irrespective of their financial or social status.
‘Yes brother,’ said his younger sister. ‘You must behave like the spherical mirror that you would often use. It reflects light to any one whosoever is being examined.’
- List at least two other ‘values’ you may like to add to the suggestion given by the senior Mr. Menon.
Answer – Equality and non-discrimination
Compassion and patience
- Name the type of spherical mirror used by dentists. Draw an appropriate ray diagram in support of your answer.
Answer – Type of mirror: Concave mirror
(Ray diagram: Parallel rays converge at focus after reflection from a concave mirror.)
Something To Do
- List those letters of English alphabet, or any other language, known to you, in which the image formed in a plane mirror appears exactly like the letter itself. Discuss your findings.
Answer – Letters that look the same in a mirror: A, H, I, M, O, T, U, V, W, X, Y
These letters are vertically symmetrical.
- You must have seen the laughing gallery (in science centres/parks/fairs) where you can see distorted and funny images in different mirrors. Using your family photographs from an old album, and pieces of different types of mirrors, try to create your own laughing gallery.
Answer – Creative activity: Use mirror pieces and photos to simulate distorted images.)
- Take three long rectangular plane mirror strips and use them to make a kaleidoscope. Put some pieces of coloured bangles in it and try to draw the images, which you see in it, on a sheet of paper.
Answer – Make a kaleidoscope using three mirror strips and observe symmetrical patterns formed.
- You must have heard the story of the lion and the rabbit, from the Panchtantra, in which the rabbit fooled the lion by showing it, its reflection in water. Try to collect some more stories which are related with the phenomenon of reflection of light.
Answer – Research stories from Panchatantra or folklore involving reflections, like the rabbit and the lion.
Additional Questions And Answers – 01
Fill in the Blanks
A plane mirror forms a virtual and _________ image.
Answer: erect
The distance between the object and the mirror is equal to the distance between the mirror and its _________.
Answer: image
A concave mirror can form both real and _________ images.
Answer: virtual
In convex mirrors, the focal length is always taken as _________.
Answer: positive
The path along which light travels is called a _________.
Answer: ray
The radius of curvature of a mirror is always _________ the focal length.
Answer: twice
Light travels in a _________ line.
Answer: straight
When light strikes a smooth surface, it undergoes _________.
Answer: regular reflection
Multiple Choice Questions (MCQs)
Which of the following always gives a virtual, erect, and diminished image?
a) Concave mirror
b) Plane mirror
c) Convex mirror
d) None
Answer: c) Convex mirror
A real image formed by a mirror is always:
a) Virtual and inverted
b) Erect and smaller
c) Inverted and can be obtained on a screen
d) Erect and magnified
Answer: c) Inverted and can be obtained on a screen
The laws of reflection are valid for:
a) Plane mirrors only
b) Curved mirrors only
c) Both plane and curved mirrors
d) Only for spherical mirrors
Answer: c) Both plane and curved mirrors
The focal length of a concave mirror is:
a) Positive
b) Negative
c) Zero
d) Depends on the object
Answer: b) Negative
A ray of light falling perpendicular to a plane mirror:
a) Gets absorbed
b) Gets refracted
c) Gets reflected back along the same path
d) Gets scattered
Answer: c) Gets reflected back along the same path
True/False
- The image formed by a convex mirror is always real and inverted.
Answer: False - Light does not change its path when it strikes a shiny surface.
Answer: False - Plane mirrors can form real images.
Answer: False - The image formed in a plane mirror is always of the same size as the object.
Answer: True - A concave mirror can form a magnified virtual image.
Answer: True
Short Answer Questions
- What is lateral inversion?
Answer: Lateral inversion is the phenomenon where the left side of an object appears as the right side and vice versa in the image formed by a plane mirror. - What type of image is formed by a plane mirror?
Answer: A virtual, erect, and laterally inverted image of the same size as the object. - What is the focal length of a spherical mirror?
Answer: It is half of the radius of curvature of the mirror. - Why are convex mirrors used as rear-view mirrors in vehicles?
Answer: Because they provide a wider field of view and always form erect, diminished images. - What happens to the image when the object moves closer to a concave mirror?
Answer: The image becomes larger and may become virtual and erect if the object is very close.
Competency-Based Questions (Reasoning/Assertion)
- Assertion: Convex mirrors are used for security purposes.
Reason: Convex mirrors form enlarged images.
Answer: False — Convex mirrors provide a wider field of view but form diminished images. Correct reason is incorrect. - Assertion: A concave mirror can form a real and inverted image.
Reason: It converges light rays at a point.
Answer: True — Both assertion and reason are correct, and the reason explains the assertion. - Assertion: The image formed by a plane mirror cannot be obtained on a screen.
Reason: The image is virtual.
Answer: True — Both assertion and reason are correct and related.
Higher Order Thinking Skill (HOTS) Questions
- A boy sees his full-length image in a mirror that is only half his height. How is this possible?
Answer: This is possible because a plane mirror needs to be only half the height of a person to show their full image, due to the law of reflection and symmetry. - Why is the image in a spoon different when viewed from the inner surface versus the outer surface?
Answer: The inner surface acts as a concave mirror (can form real or magnified virtual image), while the outer surface acts as a convex mirror (forms diminished, erect virtual images). - If an object is moving towards a concave mirror, how does the image change?
Answer: The image moves from being real, inverted, and smaller (far) to real and larger (closer to focus), and finally to virtual, erect, and magnified when the object is very close.
- Long Answer Questions (50–60 words)
- Explain how images are formed in a concave mirror when the object is placed at different positions.
Answer: When the object is far from the mirror, a small inverted image forms. At the center of curvature, the image is same-sized and inverted. Between center and focus, the image is magnified and inverted. At the focus, the rays reflect parallel. Inside the focus, the image is virtual, erect, and magnified. - What are the uses of concave and convex mirrors in daily life?
Answer: Concave mirrors are used in shaving mirrors, headlights, and solar cookers as they converge light. Convex mirrors are used in rear-view mirrors and security mirrors due to their wide field of view and ability to form smaller, erect images of distant objects, helping in monitoring large areas.
Additional Questions And Answers – 02
Fill in the Blanks
- The change in direction of light by a mirror is due to the ________ of light.
Answer: Reflection
- Reflection from non-shiny, irregular surfaces is called ________ reflection.
Answer: Diffused
- The image formed by a plane mirror is always ________ and of the same size as the object.
Answer: Virtual
- The angle between the incident ray and the normal is called the angle of ________.
Answer: Incidence
- In a spherical mirror, the ________ axis is the line joining the pole and the centre of curvature.
Answer: Principal
- The focal length of a spherical mirror is ________ the radius of curvature.
Answer: Half
- A ________ mirror has its reflecting surface curved inwards.
Answer: Concave
- A convex mirror always forms a ________, erect, and diminished image.
Answer: Virtual
- The phenomenon where the right side of an object appears as the left side in a plane mirror image is called ________ inversion.
Answer: Lateral
- Concave mirrors are used by ENT doctors as ________ mirrors to focus light.
Answer: Head
Multiple Choice Questions (MCQs)
- What type of reflection occurs on a plane, shiny surface?
- a) Diffused reflection
- b) Regular reflection
- c) Scattered reflection
- d) Irregular reflection
Answer: b) Regular reflection
- What is the nature of the image formed by a plane mirror?
- a) Real and inverted
- b) Virtual and erect
- c) Real and erect
- d) Virtual and inverted
Answer: b) Virtual and erect
- According to the laws of reflection, what is true about the angle of incidence and the angle of reflection?
- a) They are always different
- b) They are equal
- c) The angle of reflection is twice the angle of incidence
- d) The angle of incidence is zero
Answer: b) They are equal
- Where is the image formed when an object is placed at the focus of a concave mirror?
- a) At the centre of curvature
- b) Between the focus and the pole
- c) At infinity
- d) Behind the mirror
Answer: c) At infinity
- What type of image does a convex mirror always form?
- a) Real, inverted, and diminished
- b) Virtual, erect, and diminished
- c) Real, erect, and enlarged
- d) Virtual, inverted, and enlarged
Answer: b) Virtual, erect, and diminished
- What is the focal length of a spherical mirror if its radius of curvature is 20 cm?
- a) 5 cm
- b) 10 cm
- c) 20 cm
- d) 40 cm
Answer: b) 10 cm (f = r/2)
- Which mirror is used as a rear-view mirror in vehicles?
- a) Plane mirror
- b) Concave mirror
- c) Convex mirror
- d) Cylindrical mirror
Answer: c) Convex mirror
- What happens to the image in a plane mirror when the object moves closer to the mirror?
- a) The image becomes larger
- b) The image remains the same size
- c) The image becomes smaller
- d) The image becomes inverted
Answer: b) The image remains the same size
- What type of image is formed by a concave mirror when the object is between the focus and the pole?
- a) Real, inverted, and diminished
- b) Virtual, erect, and enlarged
- c) Real, inverted, and enlarged
- d) Virtual, erect, and diminished
Answer: b) Virtual, erect, and enlarged
- What instrument uses a concave mirror with a hole to examine the retina of the eye?
- a) Kaleidoscope
- b) Periscope
- c) Ophthalmoscope
- d) Telescope
Answer: c) Ophthalmoscope
True/False Questions
- Diffused reflection occurs on polished, shiny surfaces.
Answer: False (Diffused reflection occurs on non-shiny, irregular surfaces)
- The image formed by a plane mirror is always virtual and erect.
Answer: True
- The angle of incidence is equal to the angle of reflection according to the laws of reflection.
Answer: True
- A convex mirror can form a real image.
Answer: False (A convex mirror always forms a virtual image)
- The focal length of a spherical mirror is twice its radius of curvature.
Answer: False (The focal length is half the radius of curvature)
- A plane mirror can show the full image of a large object regardless of its size.
Answer: True
- Concave mirrors are used in torches as reflectors to focus light.
Answer: True
- The image formed by a concave mirror is always inverted.
Answer: False (It can be erect when the object is between the focus and the pole)
- The principal axis of a spherical mirror passes through its focus.
Answer: True
- A periscope uses convex mirrors to see overhead objects.
Answer: False (A periscope uses plane mirrors)
Short Questions and Answers
- What is regular reflection?
Answer: Regular reflection is the reflection of light from plane, shiny surfaces like mirrors, where light is reflected in an orderly manner, often causing glare.
- What is a virtual image?
Answer: A virtual image is formed by the apparent intersection of reflected rays, not by their actual intersection, and cannot be obtained on a screen.
- What are the two laws of reflection?
Answer: First law: The incident ray, normal, and reflected ray lie in the same plane. Second law: The angle of incidence equals the angle of reflection.
- What is lateral inversion in a plane mirror?
Answer: Lateral inversion is the phenomenon where the right side of an object appears as the left side in the image, and vice versa, in a plane mirror.
- What is the focus of a spherical mirror?
Answer: The focus is the point on the principal axis where rays parallel to the axis converge (concave mirror) or appear to diverge from (convex mirror) after reflection.
- Why are convex mirrors used as rear-view mirrors in vehicles?
Answer: Convex mirrors provide a wide field of view and form diminished, erect images, allowing drivers to see traffic behind them over a broader area.
- What happens to the image in a concave mirror when the object is at the centre of curvature?
Answer: The image is real, inverted, and of the same size as the object, formed at the centre of curvature itself.
- What is the relationship between the focal length and radius of curvature of a spherical mirror?
Answer: The focal length is half the radius of curvature, i.e., f = r/2.
- What type of image does a plane mirror always form?
Answer: A plane mirror always forms a virtual, erect image of the same size as the object, located as far behind the mirror as the object is in front.
- How does a kaleidoscope use mirrors?
Answer: A kaleidoscope uses two or more plane mirrors inclined at angles to create multiple images of objects, forming beautiful patterns through repeated reflections.
Competency-Based Questions (Reasoning and Assertion)
- Assertion (A): A plane mirror forms a virtual image. Reason (R): The reflected rays in a plane mirror do not actually intersect but appear to meet when produced backwards.
- a) Both A and R are true, and R is the correct explanation of A.
- b) Both A and R are true, but R is not the correct explanation of A.
- c) A is true, but R is false.
- d) A is false, but R is true.
Answer: a) Both A and R are true, and R is the correct explanation of A.
- Assertion (A): A convex mirror always forms a virtual image. Reason (R): The reflected rays in a convex mirror diverge and appear to meet behind the mirror.
- a) Both A and R are true, and R is the correct explanation of A.
- b) Both A and R are true, but R is not the correct explanation of A.
- c) A is true, but R is false.
- d) A is false, but R is true.
Answer: a) Both A and R are true, and R is the correct explanation of A.
- Assertion (A): The image formed by a concave mirror is always real. Reason (R): A concave mirror can form a virtual image when the object is between the focus and the pole.
- a) Both A and R are true, and R is the correct explanation of A.
- b) Both A and R are true, but R is not the correct explanation of A.
- c) A is true, but R is false.
- d) A is false, but R is true.
Answer: d) A is false, but R is true.
- Assertion (A): The angle of incidence equals the angle of reflection in a plane mirror. Reason (R): This is a statement of the second law of reflection.
- a) Both A and R are true, and R is the correct explanation of A.
- b) Both A and R are true, but R is not the correct explanation of A.
- c) A is true, but R is false.
- d) A is false, but R is true.
Answer: a) Both A and R are true, and R is the correct explanation of A.
- Assertion (A): A plane mirror can show the full image of a large object. Reason (R): The size of the mirror does not affect the ability to reflect the entire object.
- a) Both A and R are true, and R is the correct explanation of A.
- b) Both A and R are true, but R is not the correct explanation of A.
- c) A is true, but R is false.
- d) A is false, but R is true.
Answer: c) A is true, but R is false. (The mirror must be at least half the height of the object to show the full image.)
High Order Thinking Skill (HOTS) Questions and Answers
- Why does a plane mirror show lateral inversion, and how does this affect reading text in a mirror?
Answer: A plane mirror reverses left and right because it reflects light directly back, swapping the sides of the object in the image. This lateral inversion makes text appear reversed, making it unreadable unless viewed through another mirror or mentally reversed.
- How does the position of an object affect the nature of the image formed by a concave mirror?
Answer: In a concave mirror, if the object is beyond the centre of curvature, the image is real, inverted, and diminished. At the centre, it’s real, inverted, and same-sized. Between the centre and focus, it’s real, inverted, and enlarged. At the focus, it’s at infinity. Between the focus and pole, it’s virtual, erect, and enlarged.
- Why are convex mirrors preferred over plane mirrors for rear-view mirrors in vehicles?
Answer: Convex mirrors provide a wider field of view by forming diminished, virtual, and erect images, allowing drivers to see more traffic behind them. Plane mirrors, with a narrower field of view and same-sized images, are less effective for monitoring a broad area in vehicles.
- How can the laws of reflection be applied to find the focus of a concave mirror experimentally?
Answer: Direct parallel rays (e.g., from sunlight) onto a concave mirror. According to the laws of reflection, these rays reflect and converge at the focus. Adjust a screen until a sharp, bright spot appears—this is the focus, as the angle of incidence equals the angle of reflection at each point.
- Why does a concave mirror form a real image when the object is beyond the focus, but a virtual image when the object is between the focus and the pole?
Answer: Beyond the focus, reflected rays converge to a point in front of the mirror, forming a real image. Between the focus and pole, the rays diverge after reflection, appearing to meet behind the mirror when produced backwards, forming a virtual image.
Long Questions and Answers (50-60 words)
- Explain the two laws of reflection and their application in plane mirrors.
Answer: The first law states that the incident ray, reflected ray, and normal lie in the same plane. The second law states that the angle of incidence equals the angle of reflection. In plane mirrors, these laws ensure the image is virtual, erect, and as far behind the mirror as the object is in front.
- Describe the characteristics of the image formed by a plane mirror.
Answer: A plane mirror forms a virtual, erect image of the same size as the object, located as far behind the mirror as the object is in front. The image exhibits lateral inversion, where the right side of the object appears as the left side in the image, and it cannot be obtained on a screen.
- How does a concave mirror form images when the object is at different positions?
Answer: In a concave mirror, if the object is beyond the centre of curvature, the image is real, inverted, and diminished. At the centre, it’s real, inverted, and same-sized. Between the centre and focus, it’s real, inverted, and enlarged. At the focus, it’s at infinity. Between the focus and pole, it’s virtual, erect, and enlarged.
- What are the practical uses of concave mirrors in daily life?
Answer: Concave mirrors are used by ENT doctors as head mirrors to focus light on patients’ throats or ears, by dentists to magnify teeth, and as reflectors in torches. Ophthalmoscopes use concave mirrors with a hole to examine the retina, and they’re also used in telescopes for viewing distant objects.
- How does a convex mirror differ from a plane mirror in terms of image formation?
Answer: A convex mirror always forms a virtual, erect, and diminished image between the focus and pole, regardless of object position, providing a wider field of view. A plane mirror forms a virtual, erect image of the same size as the object, with lateral inversion, and a narrower field of view.