How Do Real and Virtual Images Form? Explained with Examples
Understanding the Difference Between Real Image And Virtual Image is essential in optics, which is a significant topic in competitive exams like JEE and NEET. Clear knowledge of how these images form helps in solving problems on reflection, refraction, and lens applications efficiently.
Definition of Real Image
A real image is formed when light rays actually converge and meet after reflection or refraction from a mirror or lens. This image can be projected onto a screen and is always formed on the side opposite to the object. For more about image formation, study the Mirror Formula And Magnification.
In real images, the image is usually inverted and can be captured physically because the rays actually pass through the location of the image.
Definition of Virtual Image
A virtual image forms when outgoing light rays appear to diverge from a specific point but do not actually meet. The image is seen by looking into the optical device, but it cannot be projected onto a screen. Review Reflection And Transmission Of Waves for related concepts.
Virtual images are usually erect and are formed on the same side as the object with respect to the mirror or lens.
Difference Table
| Real Image | Virtual Image |
|---|---|
| Formed by actual convergence of light rays | Formed by apparent divergence of rays |
| Can be projected onto a screen | Cannot be projected onto a screen |
| Always inverted | Always erect |
| Formed on opposite side to the object | Formed on same side as the object |
| Commonly formed by concave mirrors and convex lenses | Commonly formed by plane mirrors, convex mirrors, and concave lenses |
| Light rays really pass through the image location | Light rays do not really pass through the virtual image location |
| Seen by placing a screen at the image position | Seen only by looking through the optical device |
| Image is always diminished or magnified as per object position | Image is usually of same size or smaller |
| Example: Image on cinema screen | Example: Reflection in a plane mirror |
| Real images exist at a real, measurable position | Virtual images exist only by perception |
| Can form on photographic films | Cannot form on photographic films |
| Important in cameras and projectors | Important in mirrors for viewing reflection |
| Sign convention: Image distance is positive | Image distance is negative in convention |
| Observing involves physical placement of screen | Observation directly through the lens or mirror |
| Example: Human eye lens forming real image on retina | Example: Magnifying glass showing enlarged virtual image |
| Utilized in laboratory experiments | Utilized in day-to-day mirrors |
| Mirrors and lenses both can produce | Usually produced by mirrors more often |
| Magnitude determined by formula $1/v + 1/u = 1/f$ | Apparent position calculated as per object and lens position |
| Significance in optical instruments like microscopes | Significance in visual appearance or dressing mirrors |
| Explained using Sign Convention In Optics | Explained using Sign Convention In Optics |
Key Differences
- Real image formed by actual intersection of rays
- Virtual image formed by apparent divergence of rays
- Real image can be projected on a screen
- Virtual image cannot be captured on a screen
- Real images are inverted in nature
- Virtual images are always erect
Examples
The image formed on a cinema screen by a projector is a real image. The image you see in a plane mirror every day is a virtual image. Each type is described further under Difference Between Mirror And Lens.
Applications
- Real images used in cameras and projectors
- Virtual images used in shaving and dressing mirrors
- Real images critical in scientific instruments
- Virtual images essential in periscopes and rearview mirrors
- Real images useful for photographic film exposure
- Virtual images applicable in simple magnifiers
One-Line Summary
In simple words, Real Image occurs by actual meeting of light rays and is projectable, whereas Virtual Image only appears where rays seem to meet and cannot be projected.
FAQs on What Is the Difference Between Real Image and Virtual Image?
1. What is the difference between a real image and a virtual image?
Real images are formed when light rays actually converge at a point, while virtual images are created when light rays only appear to diverge from a point. Main differences include:
- Real images can be projected on a screen; virtual images cannot.
- Real images are always inverted; virtual images are usually erect.
- Real images form on the same side as the object (for mirrors) or opposite side (for lenses), while virtual images form on the same side as the observer.
2. What is a real image?
A real image forms when actual light rays meet at a point after reflection or refraction, and it can be obtained on a screen. Key features are:
- It is always inverted relative to the object.
- It can be captured or projected on a screen.
- Formed by devices like concave mirrors (beyond the focal point) or convex lenses (beyond 2F).
3. What is a virtual image?
A virtual image appears to form at a place from which light rays seem to come but do not actually meet; it cannot be projected onto a screen. Important points include:
- It is always erect relative to the object.
- It cannot be captured on a screen.
- Commonly formed by plane mirrors, convex mirrors, and concave lenses.
4. Give two differences between a real image and a virtual image.
Key differences between real and virtual images are:
- Real images can be obtained on a screen; virtual images cannot.
- Real images are inverted; virtual images are erect.
5. Can a virtual image be caught on a screen?
No, a virtual image cannot be caught on a screen because light rays do not actually meet at the image location; they only appear to diverge from there.
6. Which type of mirror forms only virtual images?
Convex mirrors form only virtual, erect, and diminished images regardless of the object's position, making them useful in rearview mirrors and security mirrors.
7. State one example each of a real and a virtual image from daily life.
A common example of a real image is the image formed on a cinema screen using a projector. An example of a virtual image is your reflection seen in a plane mirror.
8. What are the characteristics of real and virtual images?
Characteristics of real images:
- Formed where light rays actually converge.
- Can be projected on a screen.
- Always inverted.
- Formed where light rays only appear to diverge.
- Cannot be projected on a screen.
- Always erect.
9. Why is the image formed by a concave mirror sometimes real and sometimes virtual?
A concave mirror can form a real image when the object is placed beyond the focal point (the image is inverted and can be caught on a screen). It forms a virtual image when the object is placed between the mirror and focal point (the image is erect and cannot be caught on a screen).
10. How can you distinguish between real and virtual images formed by lenses or mirrors?
You can distinguish between real and virtual images by:
- Checking if the image can be projected on a screen (real) or not (virtual).
- Observing orientation: real images are inverted; virtual images are erect.
- Considering device used: concave mirrors and convex lenses usually form real images, while convex mirrors and concave lenses form virtual images.
