Tabular Comparison: Mirror vs Lens with Examples and Formulas
The Difference Between Mirror and Lens is foundational in optics and repeatedly tested in JEE Main Physics. Both mirrors and lenses form images, but their working principles differ: mirrors involve reflection of light, while lenses operate using refraction. Grasping this contrast helps you solve ray diagrams, image formation questions, and numerical problems efficiently.
A mirror is an optical device that creates images by bouncing light off its surface. In contrast, a lens is a transparent material that bends or refracts the light that passes through it. The physical processes—reflection versus refraction—lie at the heart of all further differences between these devices.
For JEE, knowing the difference between reflection and refraction is essential before comparing mirrors and lenses. While both may appear in practical applications like telescopes or cameras, their physics and formulas — including sign conventions — are distinct.
Tabular Comparison: Difference Between Mirror and Lens
| Aspect | Mirror | Lens |
|---|---|---|
| Governing Process | Reflection of light | Refraction of light |
| Material Type | Opaque shiny surface | Transparent medium |
| Image Formation | By bouncing light back | By bending light through body |
| Ray Direction | Light returns to same medium | Light passes into another medium |
| Formula | Mirror formula: 1/f = 1/v + 1/u | Lens formula: 1/f = 1/v - 1/u |
| Image Types | Real or virtual, upright or inverted | Real or virtual, upright or inverted |
| Common Uses | Rearview mirrors, shaving mirrors | Glasses, cameras, microscopes |
In JEE, you may encounter tabular differences, ray diagram interpretations, and formula sign confusion. The above table clarifies the major exam-relevant distinctions concisely.
Image Formation: Real and Virtual in Mirrors vs Lenses
The Difference Between Mirror and Lens becomes most vivid in their image formation processes. Ray diagrams help visualize how each produces real and virtual images, whether the device is concave, convex, or plane.
A concave mirror can form a real, inverted image when the object is outside the focal point, and a virtual, erect one when inside. Check concave mirror image formation for diagrams and formulas.
A convex lens (also called converging lens) forms a real, inverted image if the object is beyond the focal length, and a virtual, erect image if within the focal length. See convex and concave lenses for detailed cases.
- Mirrors reflect rays; real images form on same side as object.
- Lenses refract rays; real images form on opposite side to object.
- Virtual images: both can produce, but location and sign conventions differ.
- Image size, orientation, and distance depend on object position and focal length.
Master sign conventions using reference resources like sign convention of lens and mirror. Misapplying these conventions is a frequent JEE trap.
Mirror Formula vs Lens Formula: Definitions and JEE Application
JEE Main frequently tests formula-based distinctions within the Difference Between Mirror and Lens. Both use a focal length (f), object distance (u), and image distance (v), but their formulas and sign conventions differ.
- Mirror formula: 1/f = 1/v + 1/u
- Lens formula: 1/f = 1/v - 1/u
- u: object distance (always measured from pole/principal axis)
- v: image distance (may be positive or negative, use sign convention)
- f: focal length (plus for convex/concave as per device)
For example, a concave mirror with f = -20 cm forms an image of an object at u = -30 cm:
Mirror formula gives: 1/(-20) = 1/v + 1/(-30) ⇒ v = -60 cm (real, inverted image).
If a convex lens has f = +10 cm and u = -15 cm:
Lens formula: 1/10 = 1/v - 1/(-15) ⇒ v = +30 cm (real, inverted image on opposite side).
Always check the sign conventions and the nature (concave/convex) and direction (object/image) for each device. Review the mirror formula and magnification and ray path in optics for strengthened understanding.
Everyday Examples and Uses: Difference Between Mirror and Lens in Practice
- Plane mirrors in dressing tables (image formation, reflection property)
- Convex lenses in magnifying glasses (refraction and focusing)
- Rearview mirrors in vehicles (convex, wide field, always virtual images)
- Spectacles use concave or convex lenses for vision correction
- Cameras and projectors use lenses to focus images onto sensors/screens
Applications pop up in telescopes, microscopes, headlights, and scientific experiments. Explore the optics page for broader topics and real-world connections.
- Mirrors: Used for redirecting light beams, daily use in personal grooming
- Lenses: Used for magnification, focusing, vision correction
- Spherical mirrors find use in astronomical telescopes
- Compound microscopes and refracting telescopes rely on smart lens combinations
- Optical instruments often combine both devices for advanced functions
Vedantu’s structured explanations clarify distinctions with JEE-aligned notes and diagrams. Their resources regularly help students avoid critical conceptual errors in this chapter.
- Mixing up reflection and refraction laws for different devices
- Wrong formula: using mirror formula for lens problems (or vice versa)
- Incorrect sign convention—especially with negative focal lengths
- Forgetting real image vs virtual image differences in exam explanations
- Poor ray diagram construction on lenses versus mirrors
Sharpen your preparation by solving optics practice papers, revising Physics revision notes, and exploring related concepts like the difference between real image and virtual image.
In summary, the Difference Between Mirror and Lens pivots on reflection versus refraction, their light path manipulation, formulae, and everyday applications. Master these distinctions for confident, error-proof answers in JEE Main Physics.
FAQs on Difference Between Mirror and Lens: Key Concepts for JEE, NEET, and Boards
1. What is the main difference between a mirror and a lens?
The main difference between a mirror and a lens is that a mirror reflects light while a lens refracts light.
Key differences include:
- Mirrors form images by reflection of light from their surface.
- Lenses form images by bending (refracting) light as it passes through them.
- Mirrors are usually made of glass with a reflective coating on one side.
- Lenses are transparent and bend light rays to converge or diverge.
2. What is the difference between a real image in a mirror and a lens?
Real images differ in formation by mirrors and lenses.
- Mirror: A concave mirror forms a real image when the object is placed beyond its focus. The image is formed in front of the mirror and can be projected on a screen.
- Lens: A convex lens forms a real image when the object is outside the principal focus. The image is formed on the opposite side of the lens from the object and can also be projected on a screen.
3. How do you know that a mirror is different from a lens?
You can distinguish a mirror from a lens by observing how they affect light.
- A mirror reflects light back, forming an image on the same side as the object.
- A lens allows light to pass through and refracts it, forming an image on the opposite or same side, depending on the lens type.
- Mirrors are opaque and have a reflective surface, while lenses are transparent and have curved surfaces.
4. What is the difference between a mirror and a virtual image lens?
Mirrors and lenses both can form virtual images, but the formation process differs.
- A mirror (like a plane or convex mirror) forms a virtual image by reflecting light rays that appear to diverge from behind the mirror.
- A lens (like a concave lens) forms a virtual image by causing light rays to diverge so they appear to come from a point on the same side as the object.
- Virtual images formed by mirrors are always upright and cannot be projected on a screen.
5. What is the difference between mirror and lens in tabular form?
The main differences between mirrors and lenses can be shown in a table:
| Mirror | Lens |
|---|---|
| Reflects light | Refracts light |
| Images form on the same side as object (mirror side) | Images can form on same or opposite side |
| Can be plane, concave or convex | Can be concave (diverging) or convex (converging) |
| Opaque with reflective coating | Transparent glass or plastic |
6. Give examples of mirrors and lenses used in daily life.
Some common examples of mirrors and lenses in our daily life are:
- Mirrors: Bathroom mirrors, car rearview mirrors, makeup mirrors, telescope mirrors, and dentist's mirrors.
- Lenses: Eyeglasses, magnifying glasses, camera lenses, microscope lenses, and contact lenses.
7. What is the difference between convex mirror and convex lens?
A convex mirror and a convex lens have opposite functions with light:
- A convex mirror diverges (spreads out) the parallel rays of light after reflection. It always forms virtual, diminished, and upright images.
- A convex lens converges (brings together) the parallel rays of light after refraction. It can form real or virtual, magnified or diminished images depending on the object's position.
8. What is the difference between concave and convex mirror?
The key difference between a concave mirror and a convex mirror lies in their shapes and image formation:
- Concave mirror: Has an inward curved reflective surface. It can produce real or virtual images, magnified or diminished, based on the object's position.
- Convex mirror: Has an outward curved reflective surface. It always forms virtual, erect, and diminished images.
9. What is the difference between concave mirror and concave lens?
A concave mirror and a concave lens differ in how they affect light and form images:
- Concave mirror: Reflects light and can form both real and virtual images, used in torches and headlights.
- Concave lens: Refracts light and always forms virtual, erect, and diminished images, used in spectacles for myopia.
10. What is the difference between mirror and glass?
A mirror has a reflective coating on its back to reflect light, while glass is a transparent material that allows light to pass through.
- Mirror: Used for reflection and forming images.
- Glass: Used for transparency, allowing light and objects behind to be seen.
- Mirrors form images by reflection, glass does not form images on its own.
11. State the difference between concave mirror and convex lens with examples.
A concave mirror and a convex lens differ in structure and uses:
- Concave mirror: Inward curved, reflects light, used in shaving mirrors and headlights.
- Convex lens: Outward curved on both sides, refracts light, used in magnifying glass and camera lenses.
12. How do mirrors and lenses form images?
Mirrors form images by reflecting light rays, while lenses form images by bending (refracting) light rays.
- Mirrors: The image position and nature depend on the object distance from the mirror and the mirror's shape.
- Lenses: The image can be real or virtual, magnified or diminished, based on the type of lens and position of the object.
