Concave and Convex Spherical mirrors - Definition, Types, Uses, Image Formation, FAQs

Edited By Vishal kumar | Updated on Jul 02, 2025 04:25 PM IST

Define Spherical Mirror.

Spherical mirror definition and spherical meaning:
A spherical mirror is any visible area that illuminates the light and produces a realistic image or virtual image. When an object is placed in front of a spherical mirror, a picture of the same object appears on the aperture of the mirror or aperture of a spherical mirror. The object is the source of the incident radiation, and the image is made up of reflected radiation. Depending on the interaction of light, images are classified as realistic or virtual imagery. The actual image occurs when the light rays meet while the virtual images appear due to the apparent difference of the light rays from the point.
Ray's drawings help us to trace the path of light so that one can see the point in the object image. Ray's drawing uses of spherical mirror lines with arrows to represent the event rays and the ray shown. It also helps us to keep track of where the light is going.

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Define Spherical Mirror.
Circular spherical mirrors
Concave spherical mirror
Convex spherical mirror
Use of Convex Spherical mirror

Concave and Convex Spherical mirrors - Definition, Types, Uses, Image Formation, FAQs

Plane mirror vs Spherical mirrors and types of spherical mirror:

Spherical mirrors are made in different shapes for different purposes.

The two most prominent types of spherical mirrors are:

Plane mirrors

Circular spherical mirrors

The flight screen is a smooth glow. The flight screen always creates a straightforward virtual image, and with the same shape and size as the object, it shows. A circular spherical mirror is a spherical mirror with a constant curve and a continuous curved width. Images created with a circular spherical mirror can be real or virtual. Circular spherical mirrors of two types such as:

Concave spherical mirror

Convex spherical mirror

In the next few sections, let’s take a closer look at the features of interlocking and overlocking spherical mirrors and images created by them when an object is stored in various locations.

Circular spherical mirrors

Circular spherical mirrors are spherical mirrors with curved areas painted on one side. The circular spherical mirrors of the interior are known as convex spherical mirrors, while the circular spherical mirrors of the exterior are known as concave spherical mirrors.

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Concave spherical mirror

If the empty area is cut into parts and the outside of the cut part is painted, then it becomes a spherical mirror with its inner surface as a luminous surface. The given type of spherical mirror is called a concave spherical mirror.

Features of Concave Spherical mirrors

The light meets when it strikes and reflects back from the reflective surface of the concave spherical mirror. Therefore, it is also known as a flexible spherical mirror.

When a concave spherical mirror is placed too close to an object, a magnified and visible image is obtained.

However, if we increase the distance between the object and the spherical mirror the image size decreases and a real image is formed.

The image created by the concave spherical mirror can be small or large or real or virtual.

Convex spherical mirror

If a cut part of a blank field is painted on the inside, then its exterior becomes a bright spot. The given type of spherical mirror is called a convex spherical mirror.

NCERT Physics Notes :

Features of Convex Spherical mirrors

A convex spherical mirror is also known as a diversion spherical mirror as it separates light when striking in its bright spot.

virtual, vertical, and abstract images are usually constructed of convex spherical mirrors, regardless of the distance between the object and the spherical mirror.

Use of Convex Spherical mirror

Convex spherical mirrors are usually used in the corridors of buildings that include shops, schools, hospitals, hotels and apartment buildings.

They are used on sidewalks, sidewalks, and ropes to provide safety for all cyclists and riders at curves and other places where they are not visible.

They are also used in other automated reporting systems as an usable security feature that allows the user to see what is happening behind them.

They are used on the sidewalk of a car and in one place it says “things in the spherical mirror are closer than they look” to warn the driver.

Image formation with Convex spherical mirror

There are two possibilities terms related to spherical mirror to the shape of an object in a convex spherical mirror.

When an object is in an infinite position, a balanced image is formed with the main focus being behind the convex spherical mirror. The built-in image is very thin, virtual and upright.

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When the Object is between the end and the pole

When the object is between the end and the convex spherical mirror pole, a thin, virtual and vertical image is formed between the pole and the focus that is behind the spherical mirror. The built-in image is slender, visible and upright.

A concave spherical mirror, also called a flexible spherical mirror, has its own space that shows the explosion inside, e.g. Away from the incident light. There are many uses of concave spherical mirrors in everyday life. It is used for the arrival of planes to steer the plane, is used as a lamp to reflect light rays, is used during shaving to get a standing and enlarged face image, etc.

Other uses of the concave spherical mirror are listed at the bottom points.

Shaving glasses

Head spherical mirrors

Ophthalmoscope

Star telescopes

Front lights

Solar panels

Concave spherical mirrors reflect light within a single focused light. Therefore, they are used to focusing on light. A concave spherical mirror shows different types of image depending on the distance between the spherical mirror and the object. Concave spherical mirrors are called interlocking spherical mirrors because as light falls on the screen, it collects light and recovers the corresponding incoming radiation. Some of the most important and common applications of concave spherical mirrors are described below.

Used for shaving glasses

Concave spherical mirrors are often used for shaving due to the bright and sharp surface. During shaving, the concave spherical mirror creates a magnified and upright image of the face when the spherical mirror is held close to the face.

The Concave spherical mirror uses an ophthalmoscope

Concave spherical mirrors are used in virtual aids such as the Ophthalmoscope. The Ophthalmoscope contains a delicate spherical mirror with a hole in the center. The doctor focuses on a small hole in the back of the concave spherical mirror while a bright light is directed at the patient's eye. This makes the retina more visible and makes it easier for doctors to examine.

The use of concave spherical mirror in astronomical telescopes

Concave spherical mirrors are also used to make star telescopes. On an astronomical telescope, a concave spherical mirror of 5 feet [5 m] or more is used.

Concave spherical mirrors used in front lights

Concave spherical mirrors are widely used in car and car lights, headlights, train engines, etc. as indicators. The light source is placed in the spherical mirror storage area, so after exposure the light rays travel as far as the corresponding light rays of greater intensity.

Used in solar panels

Large concave spherical mirrors are used to focus on the sun to produce heat in the solar furnace.

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Frequently Asked Questions (FAQs)

1. What are the rules of concave and convex spherical mirrors?

Guidelines for Radiation Falling on the Concave and Convex Spherical mirrors.

When a ray strikes concave or convex spherical mirrors unevenly on its pole, it appears inappropriate.

When a ray, like the main axis strikes concave or convex spherical mirrors, the reflected ray passes through the focus on the main axis.

2. What is the focus of a concave mirror?

Light rays that are parallel to the principal axis of a concave mirror converge at a specific point on its principal axis after reflecting from the mirror.

3. What are some other uses of concave spherical mirrors?

Concave spherical mirrors are used as search lights, shaving spherical mirrors, satellite dishes, and much more. These spherical mirrors have a meeting place and focus light rays. Concave spherical mirrors with flashlights and headlights are used as indicators.

4. How do doctors use a concave spherical mirror?

Concave glasses help to produce a larger image helps doctors to examine body parts and are used in the manufacture of light-emitting night light equipment. Concave spherical mirrors are used to focus on the sun to produce heat from the sun

5. Why do we like a convex spherical mirror in cars?

We like the interlocking spherical mirror as a rear view spherical mirror for cars because it provides a wide viewing area, allowing the driver to see most of the cars behind him. ... Convex spherical mirrors always create a clear, well-designed and subdued image of objects placed in front of it

6. How do spherical mirrors demonstrate the law of reflection?

Spherical mirrors demonstrate the law of reflection at every point on their surface. The angle of incidence always equals the angle of reflection, measured from the normal (perpendicular) to the mirror surface at the point of reflection.

7. What is the difference between a parabolic mirror and a spherical mirror?

A parabolic mirror has a parabolic cross-section, while a spherical mirror has a circular cross-section. Parabolic mirrors can focus parallel light rays to a single point without spherical aberration, making them ideal for applications like telescopes and satellite dishes.

8. What is spherical aberration and how does it affect image quality in spherical mirrors?

Spherical aberration is an optical effect where light rays reflecting from different parts of a spherical mirror don't converge to a single focal point. This can cause blurring or distortion in the image, especially for rays reflecting far from the mirror's center.

9. How does the focal length of a spherical mirror relate to its focusing power?

The focal length is inversely proportional to the mirror's focusing power. A shorter focal length means a higher focusing power, as the mirror bends light rays more sharply. This relationship is expressed as Power = 1/focal length.

10. How does the radius of curvature affect the focusing power of a spherical mirror?

The smaller the radius of curvature, the greater the focusing power of the mirror. This is because a smaller radius results in a shorter focal length, causing light rays to converge or diverge more sharply after reflection.

11. Can a concave mirror ever produce a virtual image?

Yes, a concave mirror can produce a virtual image when the object is placed between the focal point and the mirror surface. In this case, the reflected rays diverge, similar to a convex mirror.

12. How does the size of the image change as an object moves towards a concave mirror?

As an object moves from infinity towards a concave mirror, the image size initially decreases until the object reaches the center of curvature. Then, the image size increases as the object moves closer to the focal point and beyond.

13. How does the nature of the image change when an object moves from infinity to the mirror surface for a concave mirror?

For a concave mirror, as the object moves from infinity to the mirror surface, the image changes as follows: real and inverted (beyond C) → real and same size at C → real, inverted and magnified (between C and F) → infinitely large at F → virtual, erect and magnified (between F and mirror).

14. Can a concave mirror ever produce an upright image?

Yes, a concave mirror can produce an upright image when the object is placed between the focal point and the mirror surface. This image will be virtual, erect, and magnified.

15. What is the significance of the center of curvature in spherical mirrors?

The center of curvature is the center of the sphere of which the mirror is a part. It's significant because any incident ray passing through this point will be reflected back along the same path, helping in ray diagrams and image formation analysis.

16. What determines whether a spherical mirror is concave or convex?

The direction of the mirror's curve determines its type. If the reflecting surface curves inward towards the center of the sphere, it's concave. If it curves outward away from the center, it's convex.

17. What is the relationship between the focal length and radius of curvature for a spherical mirror?

For a spherical mirror, the focal length (f) is half the radius of curvature (R). This relationship is expressed as f = R/2. This applies to both concave and convex mirrors.

18. Why don't convex mirrors have a real image position?

Convex mirrors don't have a real image position because the reflected light rays always diverge after reflection. They never converge to form a real image, instead creating a virtual image behind the mirror.

19. What is the basic difference between concave and convex spherical mirrors?

Concave mirrors curve inward like the inside of a bowl, focusing light to a point. Convex mirrors curve outward like the outside of a ball, spreading light out. This fundamental shape difference leads to their distinct optical properties and uses.

20. How does the focal point of a concave mirror differ from that of a convex mirror?

A concave mirror has a real focal point in front of the mirror where light rays actually converge. A convex mirror has a virtual focal point behind the mirror where light rays appear to diverge from, but don't actually meet.

21. What is meant by the term "optical axis" in relation to spherical mirrors?

The optical axis, also known as the principal axis, is an imaginary line that passes through the center of curvature and the vertex (pole) of the spherical mirror. It serves as a reference line for measuring distances and angles in mirror calculations and ray diagrams.

22. What is the significance of the principal axis in spherical mirrors?

The principal axis is an imaginary line passing through the center of curvature and the pole (vertex) of the mirror. It's significant because it helps define the mirror's geometry and is used as a reference line for ray diagrams and calculations in image formation.

23. How does the radius of curvature affect the focal length of a spherical mirror?

The focal length of a spherical mirror is directly proportional to its radius of curvature. Specifically, the focal length is half the radius of curvature (f = R/2). A mirror with a larger radius of curvature will have a longer focal length.

24. What is the significance of the center of curvature in image formation for spherical mirrors?

The center of curvature is important in image formation because any ray passing through it will be reflected back along the same path. This property is useful in constructing ray diagrams and understanding how images are formed at different object positions.

25. How does the mirror equation relate object distance, image distance, and focal length?

The mirror equation relates object distance (u), image distance (v), and focal length (f) as: 1/f = 1/u + 1/v. This equation applies to both concave and convex mirrors and helps calculate unknown values when two of the three are known.

26. Why do convex mirrors always produce virtual images?

Convex mirrors always produce virtual images because the reflected light rays diverge after reflection, never actually meeting. Our brain interprets these diverging rays as coming from a virtual image behind the mirror.

27. Why are convex mirrors often used as security mirrors in stores?

Convex mirrors are used as security mirrors because they provide a wider field of view than flat mirrors. They can show a larger area of the store in a compact space, making it easier to monitor activities.

28. Why are convex mirrors preferred for side-view mirrors in vehicles?

Convex mirrors are preferred for side-view mirrors because they provide a wider field of view, reducing blind spots. They make objects appear smaller and farther away, which is why they often come with the warning "Objects in mirror are closer than they appear."

29. How does the magnification of an image change with object distance for a convex mirror?

For a convex mirror, as the object moves closer to the mirror, the magnification of the image increases slightly. However, the image always remains upright, virtual, and smaller than the object.

30. How does the sign convention work for spherical mirrors?

In the sign convention for spherical mirrors, distances measured in the direction of incident light are considered positive, while those measured opposite to the incident light are negative. The mirror's vertex is the origin, and the principal axis extends horizontally.

31. What happens to the image when an object is placed exactly at the focal point of a concave mirror?

When an object is placed exactly at the focal point of a concave mirror, no clear image is formed. The reflected rays become parallel to each other and to the principal axis, effectively going to infinity.

32. How does the position of the principal focus affect image formation in spherical mirrors?

The principal focus is crucial in image formation. For concave mirrors, it determines where parallel rays converge after reflection. For convex mirrors, it's the point from which reflected rays appear to diverge. Its position relative to the object determines the nature and position of the image.

33. Why do dentists often use concave mirrors?

Dentists use concave mirrors because they can produce magnified, upright images of teeth when held close to the mouth. This allows dentists to see small details more clearly during examinations and procedures.

34. What is meant by the term "real image" in the context of spherical mirrors?

A real image is formed when light rays actually converge at a point after reflection. It can be projected on a screen and is inverted relative to the object. Real images are formed by concave mirrors when the object is beyond the focal point.

35. How does a convex mirror's field of view compare to that of a plane mirror?

A convex mirror has a wider field of view compared to a plane mirror of the same size. This is because the convex surface causes light rays from a wider area to be reflected towards the observer, allowing them to see more of their surroundings.

36. Why do concave mirrors sometimes produce inverted images and other times produce upright images?

The orientation of the image depends on the object's position relative to the focal point. When the object is beyond the focal point, the image is inverted. When it's between the focal point and the mirror, the image is upright. This is due to the way light rays converge or diverge after reflection.

37. How do you determine if an image formed by a spherical mirror is magnified or diminished?

The magnification of an image is determined by the ratio of image height to object height. If this ratio is greater than 1, the image is magnified; if less than 1, it's diminished. For spherical mirrors, this depends on the object's position relative to the focal point and center of curvature.

38. Why are convex mirrors sometimes called diverging mirrors?

Convex mirrors are called diverging mirrors because they cause parallel incident light rays to diverge after reflection. This divergence creates the appearance that the reflected rays originate from a virtual focal point behind the mirror.

39. How does the image formation in a concave mirror change when the object is moved from infinity to the mirror surface?

As the object moves from infinity to the mirror surface, the image changes from a small, real, inverted image at the focal point, to a larger real inverted image between F and C, to a real inverted image the same size as the object at C, then to a larger real inverted image beyond C, and finally to a virtual, erect, magnified image when the object is between F and the mirror.

40. Why do concave mirrors form real images in some cases and virtual images in others?

Concave mirrors form real images when the object is beyond the focal point because reflected rays converge to a point in front of the mirror. They form virtual images when the object is between the focal point and the mirror because reflected rays diverge and appear to come from behind the mirror.

41. How does the image in a convex mirror change as an object moves closer to the mirror?

As an object moves closer to a convex mirror, the virtual image appears to move closer to the mirror and becomes slightly larger. However, the image always remains upright, virtual, and smaller than the object, regardless of the object's position.

42. What is the difference between a real focus and a virtual focus?

A real focus is a point where light rays actually converge after reflection, as in concave mirrors. A virtual focus is a point from which light rays appear to diverge after reflection, as in convex mirrors. Real foci exist in front of the mirror, while virtual foci are behind the mirror.

43. Why are concave mirrors often used in telescopes and satellite dishes?

Concave mirrors are used in telescopes and satellite dishes because of their ability to collect and focus parallel light rays to a single point. This concentrating effect allows for the collection of faint light from distant stars or weak signals from satellites.

44. How does the image formation in a convex mirror differ from that in a concave mirror?

Convex mirrors always form virtual, upright, and diminished images behind the mirror, regardless of object position. Concave mirrors can form real or virtual images, inverted or upright, magnified or diminished, depending on the object's position relative to the focal point.

45. Why do convex mirrors always produce diminished images?

Convex mirrors always produce diminished images because they cause light rays to diverge after reflection. This divergence creates a virtual image that appears smaller than the object, regardless of the object's distance from the mirror.

46. What is the difference between a real image and a virtual image?

A real image is formed when light rays actually converge at a point after reflection and can be projected on a screen. A virtual image is formed when light rays appear to diverge from a point after reflection but don't actually meet there. Virtual images cannot be projected on a screen.

47. How does the curvature of a spherical mirror affect its field of view?

The curvature of a spherical mirror affects its field of view. Convex mirrors have a wider field of view than flat mirrors because their outward curve allows them to reflect light from a larger area. Concave mirrors typically have a narrower field of view due to their inward curve.

48. Why are concave mirrors sometimes called converging mirrors?

Concave mirrors are called converging mirrors because they cause parallel incident light rays to converge to a focal point after reflection. This convergence is what allows concave mirrors to form real images under certain conditions.

49. How does the position of an object relative to a concave mirror's focal point affect the nature of the image formed?

When an object is beyond the focal point of a concave mirror, a real, inverted image is formed. When it's at the focal point, no clear image is formed. When it's between the focal point and the mirror, a virtual, upright, and magnified image is formed.

50. How does the magnification of an image relate to the object and image distances in spherical mirrors?

The magnification (m) of an image is related to the object distance (u) and image distance (v) by the equation: m = -v/u. The negative sign indicates that for real images (in concave mirrors), the image is inverted relative to the object.

51. Why do convex mirrors produce a wider field of view compared to plane mirrors?

Convex mirrors produce a wider field of view because their outward curve allows them to reflect light from a larger area onto a smaller surface. This compression of a wide area into the mirror's surface gives the observer a broader view of their surroundings.

52. How does the image change when an object crosses the focal point of a concave mirror?

When an object crosses the focal point of a concave mirror (moving towards the mirror), the image changes dramatically. It goes from being a real, inverted image beyond the center of curvature to an infinitely large image at the focal point, then to a virtual, upright, and magnified image between the focal point and the mirror.

53. What is the relationship between the focal length and the power of a spherical mirror?

The power of a spherical mirror is the reciprocal of its focal length, expressed in meters. The formula is P = 1/f, where P is the power in diopters and f is the focal length in meters. A shorter focal length results in a higher power, indicating a stronger focusing or diverging effect.

54. How do spherical mirrors demonstrate the reversibility of light paths?

Spherical mirrors demonstrate the reversibility of light paths through the principle that any ray of light will follow the same path in reverse if its direction is reversed. This means that if you swap the positions of an object and its image, the new image will form where the original object was.

55. Why are parabolic mirrors preferred over spherical mirrors for certain applications like telescopes?

Parabolic mirrors are preferred over spherical mirrors for applications like telescopes because they can focus parallel light rays to a single point without spherical aberration. Spherical mirrors, especially those with large apertures, suffer from spherical aberration where not all parallel rays converge to the same focal point, leading to image distortion.