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We see objects because light rays enter our eyes after bouncing off the objects. This bouncing of light off objects is known as reflection.
There are plane (flat) and curved mirrors. In a plane mirror the image is the same size as the object and the same way up. But it is inverted, i.e. back-to-front.
There are two types of curved mirror (convex and concave).
What are convex mirror ?
A mirror that bulges outwards is called a convex mirror. Convex mirrors show things the right way up and usually smaller.
What are concave mirror ?
A mirror that bulges inwards is called a concave mirror. (Remember you go into a cave!). How you appear in a concave mirror depends on how close you are to it. From close up you look bigger and right way up. Further away you look smaller and upside down.
Difference between concave and convex mirror
The main difference between concave and convex mirrors is the most easily seen by considering how they reflect light rays parallel and close to the principal axis.
1. If the inner surface of the spherical mirror is the reflecting surface, it is called a concave mirror. If the outer surface of the spherical mirror is the reflecting surface, it is called a convex mirror.
2. A concave mirror is called a converging mirror. Convex mirror is called a diverging mirror or fisheye mirror.
3. The focus lies in front of the mirror in concave. The focus lies behind the mirror in convex.
4. A concave mirror can be projected on the screen. The convex mirror cannot be projected on the screen.
5. A concave mirror is hollowed or rounded. Convex mirror is curved or rounded like the outside of sphere or circle.
6. For concave mirror, the reflected rays converge to the focal point F located at f = +R/2 on the principal axis. Positive sign means that the rays actually converge at and subsequently emanate from the focal point. For convex mirror, f = -R/2 and is located on the principal axis behind the mirror. Negative sign means that rays “appears” to, but actually not, converge to and then emanate from the focal point.
Image Formation by Concave Mirrors
By drawing the reflected rays by using any two of the above three ways, we can locate the image, which is either the direct intercept of the reflected rays (if the image is real) or the intercept of their extrapolations behind the mirror (if the image is virtual). An image is real if light actually converge at the image position (and so the image can be recorded by a photographic plate or visualized by a projector screen placed at the image position). Converse is true for a virtual image.
Image formation by a concave mirror for different positions of the object
A concave mirror can reflect in two different ways:
- If the object is close, the mirror will make it appear larger and right side up.
- If the object is farther away, the mirror will make it appear smaller and upside down.
| Position of the Object | Position of the Image | Size of the Image | Nature of the Image | Image Diagram |
| At Infinity | At the focus of F | High diminished, Point-sized | Real and inverted |  |
| Beyond C | Between F and C | Diminished | Real and inverted |  |
| At C | At C | Same size | Real and inverted |  |
| Between C and F | Beyond C | Enlarged | Real and inverted |  |
| At F | At Infinity | Highly enlarged | Real and inverted |  |
| Between P and F | Behind the mirror | Enlarged | Virtual and erect |  |
Image Formation by Convex Mirrors
We can establish three similar ways to draw reflected rays for a convex mirror. It turns out the image formed by a convex mirror is always virtual, upright and diminished. So one always needs to extrapolate the reflected rays behind a convex mirror to find the image.
Image formation by a convex mirror for different positions of the object
A convex mirror produces a small image standing right side up. It reflects back a larger area than a concave mirror does. Convex mirrors are used for security purposes in stores.
| Position of the Object | Position of the Image | Size of the Image | Nature of the Image |
| At Infinity | At the focus of F, behind the mirror | High diminished, Point-sized | Virtual and erect |
| Between infinity and the pole P of the mirror | Between P and F, behind the mirror | Diminished | Virtual and erect |
Uses of concave mirror:
Concave mirrors are commonly used in torches, search-lights and vehicles headlights to get powerful parallel beams of light. They are often used as shaving mirrors to see a larger image of the face. The dentists use concave mirrors to see large images of the teeth of patients. Large concave mirrors are used to concentrate sunlight to produce heat in solar furnaces.
- By dentists to examine the teeth.
- Shaving mirrors.
- Head mirrors.
- Astronomical telescopes.
- Headlights.
- Solar furnaces.
- Reflector of torch.
Uses of convex mirror:
Convex mirrors are commonly used as rear-view (wing) mirrors in vehicles. These mirrors are fitted on the sides of the vehicle, enabling the driver to see traffic behind him/her to facilitate safe driving. Convex mirrors are preferred because they always give an erect, though diminished, image. Also, they have a wider field of view as they are curved outwards. Thus, convex mirrors enable the driver to view much larger area than would be possible with a plane mirror.
- Side view mirror in vehicles.
- Vehicle mirrors.
- Magnifying glasses.
- For security purposes.
- Street light reflectors.
When you look into a mirror, you expect to see yourself reflected back – but what if that reflection could be magnified, minimized, or even appear upside down? Welcome to the fascinating world of curved mirrors, where concave vs convex mirrors create entirely different visual experiences through the science of light reflection.
Understanding the difference between concave and convex mirrors isn't just academic knowledge – it's practical science that surrounds us daily, from the side mirrors on your car to the security mirrors in stores. Let's explore these optical wonders that bend more than just light!
What Makes Mirrors "Curved"?
Before diving into the concave mirror vs convex mirror comparison, let's understand what makes these mirrors special. Unlike regular flat mirrors that reflect light at equal angles, curved mirrors manipulate light rays due to their spherical surfaces.
Quick fact: All curved mirrors follow the same fundamental principle – they're sections of a sphere, which means every part of the mirror has a specific curvature that affects how light behaves!
Concave Mirrors: The Inward Curve Wonder
What is a Concave Mirror?
A concave mirror curves inward like the inside of a spoon or a cave (hence "cave" + "cave" = concave). The reflective surface faces the hollow side, creating a mirror that can focus light to a single point.
How Concave Mirrors Work Their Magic
Light rays hitting a concave mirror converge at a focal point, making these mirrors converging mirrors. This convergence property leads to some remarkable effects:
- Objects can appear magnified
- Parallel light rays focus at one spot
- Images can be real or virtual depending on object position
Amazing Real-World Uses of Concave Mirrors
Did you know? You might have used a concave mirror today without realizing it!
- Makeup and Shaving Mirrors – The magnification helps you see fine details
- Headlights and Flashlights – Focus light into powerful beams
- Satellite Dishes – Concentrate radio waves for better reception
- Solar Cookers – Focus sunlight to generate heat
- Telescopes – Gather and focus light from distant stars
Mind-blowing fact: The Hubble Space Telescope uses concave mirrors to capture images of galaxies millions of light-years away!
Convex Mirrors: The Outward Expansion
What is a Convex Mirror?
A convex mirror curves outward like a ball's surface or the back of a spoon. The reflective coating is on the outside of the curved surface, causing light rays to scatter in different directions.
Convex Mirror Science: Light Scattering Explained
Unlike their concave cousins, convex mirrors cause light rays to diverge, earning them the name diverging mirrors. This scattering effect provides a wider field of view but creates smaller images.
Where Convex Mirrors Make Our Lives Safer
Convex mirrors are the unsung heroes of safety and security:
- Car Side Mirrors – The "Objects in mirror are closer than they appear" warning exists because convex mirrors make things look smaller
- Security Mirrors – Shopping malls use them to prevent shoplifting (yes, Big Brother is watching – with physics!)
- Parking Garages – Help drivers see around corners and avoid collisions
- ATM Security – Let you see if someone's lurking behind you
- Road Safety – Installed at blind corners to improve visibility
Interesting trivia: The phrase "Objects in mirror are closer than they appear" is required by law in the United States because convex mirrors create this optical illusion!
Side-by-Side Comparison: Concave vs Convex Mirrors
Understanding the difference between concave and convex mirrors becomes crystal clear when we compare their properties directly:
| Property | Concave Mirror | Convex Mirror |
|---|---|---|
| Curve Direction | Curves inward (like a cave) | Curves outward (like a ball) |
| Light Behavior | Converges light rays | Diverges light rays |
| Image Size | Can magnify or shrink | Always creates smaller images |
| Field of View | Narrower field of view | Wider field of view |
| Image Type | Real and virtual images possible | Only virtual images |
| Common Uses | Makeup mirrors, telescopes | Security mirrors, car mirrors |
| Reflection Focus | Focuses at a single point | No focal point |
The Image Transformation Game
One of the most fascinating aspects of the concave mirror vs convex mirror debate is how they handle image formation:
Concave Mirror Image Magic
- Object beyond center of curvature = Real, inverted, smaller image
- Object at center of curvature = Real, inverted, same size
- Object between center and focus = Real, inverted, magnified
- Object within focus = Virtual, upright, magnified
Pro tip: Ever wondered why dentists use magnifying mirrors? They're concave mirrors that create enlarged, upright images when positioned very close to your teeth!
Convex Mirror Consistency
Fun fact: No matter where you stand, a convex mirror will ALWAYS create a virtual, upright, and diminished image. It's like the reliable friend of the mirror world – consistent but always makes you look smaller!
Everyday Applications: Hidden in Plain Sight
The battle of concave vs convex mirror applications rages on in our daily lives:
At Home
- Concave: Makeup vanity mirrors, makeup compact mirrors
- Convex: Decorative wall mirrors for wide views
On the Road
- Concave: Some car headlights and fog lights
- Convex: All side-view mirrors (that's why they're smaller!)
In Stores
- Concave: Rare, but sometimes used for magnifying price tags
- Convex: Security mirrors in corners and entrances
The Science Behind the Magic
Understanding Focal Length
Key insight: Focal length determines a curved mirror's power. Concave mirrors have positive focal lengths, while convex mirrors have negative focal lengths.
- Concave mirrors can focus light to start fires (try it with a magnifying glass!)
- Convex mirrors spread light, making them perfect for flood lighting
The Mirror Equation Mystery
Both mirror types follow the same physics formula: 1/f = 1/do + 1/di
Where:
- f = focal length
- do = object distance
- di = image distance
This equation explains why concave mirrors can create both enlarged and reduced images depending on object placement – it's all about the math!
Common Misconceptions Busted
Myth #1: All Curved Mirrors Make You Look Funny
Reality: Only convex mirrors consistently distort images. Concave mirrors can actually provide clearer, magnified views.
Myth #2: Convex Mirrors Always Lie About Distance
Reality: They don't lie – they show relative distances accurately within their field of view. The "closer than they appear" warning exists because our brains expect flat mirror behavior.
Myth #3: Concave Mirrors Are Just for Vanity
Reality: They're crucial for modern technology – from LASIK eye surgery equipment to satellite communications!
Choosing the Right Mirror for Your Needs
Understanding concave vs convex mirrors helps you make smart choices:
Pick Concave When You Need:
- Magnification for detailed work
- Light concentration
- Real image formation
- Close-range viewing enhancement
Choose Convex When You Need:
- Wide field of view
- Safety monitoring
- Distance estimation over large areas
- Prevention of blind spots
The Future of Curved Mirror Technology
Modern applications continue to innovate:
- Smart mirrors using concave technology for virtual try-ons
- Advanced security systems with AI-enhanced convex monitoring
- Solar energy improvements using optimized concave collectors
- Automotive safety enhancements in convex mirror design
Quick Recap: Concave vs Convex Mirror Cheat Sheet
Remember this simple trick:
- Concave = Cave (think inward curve)
- Convex = C-shape outward bulge
Best uses:
- Concave: When you want to focus, magnify, or concentrate
- Convex: When you want to expand, monitor, or see more
The Bottom Line
The difference between concave and convex mirrors goes far beyond simple shape – it's about manipulating light to serve human needs. Whether you're applying makeup with a concave mirror's magnification or checking your blind spot with a convex mirror's wide view, these optical tools enhance our daily experiences through fundamental physics.
Understanding concave vs convex mirrors isn't just academic – it's practical knowledge that helps you appreciate the science behind common objects and make informed choices in everything from safety equipment to home purchases.
Final thought: Next time you look in a mirror, consider whether it's helping you see better, or helping you see more – because that's the real difference between concave and convex mirrors!
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Difference between Convex Mirror with Diagram vs Concave
Concave vs Convex Mirror with Diagram
Differences between Convex Mirror with Diagram vs Concave
Image Credits: Freepik
