Types of Reflection and How Images Are Formed
Reflection of Light
Can you see things around you right now? If yes, then it is mainly due to the light that is falling on those objects. When a ray of light falls on any object or anybody that is rough, smooth, or shiny, the surface of those objects bounces back those rays to our eyes. This incredible phenomenon is called the reflection of light. The only difference is that when light falls on an object with a shiny surface such as a mirror and plates, a crisp reflection or image is formed. This is because the reflection of light is uniform throughout the surface of the object. On the other hand, when light falls on an object with a rough surface such as a granite slab or polished shoes, a coarse image is formed because the reflection of light is non-uniform. When light falls on a much more irregular surface such as cemented floor or walls, the reflection is arbitrary, and hence no image is formed.
Reflection of Light Definition
Reflection of the light definition is quite simple and easy to understand. When you find a ray of light falling on a smooth object and then bouncing back, it is known as the reflection of light. It can be explained through this simple diagram.
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(the image shows the Reflection Of Light Image Diagram. Here: the incident ray is denoted by ‘i’; Reflected ray is denoted by ‘r’; P is the point of perpendicular)
In the diagram shown above, the ray of light that falls on the mirror is known as incident ray and is denoted by small ‘I’, and the ray that bounces back is known as reflected ray and is denoted by small ‘r’. The point where incident ray falls, a perpendicular is drawn, which is known as ‘normal’. This normal line basically works as a division between the reflected ray as well as the incident ray equally and even offers an “angle of incidence” and “angle of reflection”.
The above discussion gives us the Law Of Reflection of light that says:
The angle of incidence and reflection are equal.
The reflected ray, the normal and the incident ray, they all fall in the same plane.
Types of Reflection
There are mostly two types of reflection, one is the regular reflection, and the other is irregular reflection.
Regular Reflection- a regular reflection is basically known as a mirror-like reflection. In this case, the rays of light coming from an object will be falling on a smooth as well as a shiny object such as a mirror and then being reflected at a definite angle. Here, as per the theory of reflection, both the angles of incidence and reflection will be equal to each other. Thus it forms a crisp and clear image of the object. This is because the light falls on a smooth and shiny surface.
Irregular Reflection- this type of reflection is not similar to a mirror-like reflection. In this type of reflection, you can find the ray of light falling on an irregular object possessing a rough surface such as a water surface. As per the theory, such a surface will reflect the light in all possible directions. However, both the angles of the incident and the reflection, in this case, are not at all equal. Therefore, it will not form an image or a very rough image.
Virtual Image and Real Image
A mirror can create two different types of images, virtual image, and real image. When light from any single source spreads out after passing through a lens after being reflected, a virtual image is formed. When light falls on a mirror, the image will always appear to be behind the mirror, but this is impossible since the light does not pass through the image but is reflected. This way a virtual image is created by the reflection of light from a mirror. Therefore it is clear that any image we see from the reflection of light by a plane flat mirror is always a virtual image. The concept of the virtual image will be clearer with the help of the image given below.
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(The image displays the concept of virtual image with the help of incident rays and reflected rays)
On the other hand, real images are formed when the rays of light pass through the lens and meet or converge at a single point on the other side of the lens. Since the rays are converging, it means that the image, which is formed, actually exists. Therefore you place a screen on the path of the real image the image will be created on the screen. Short and simple, virtual image occurs when the ray of light does not meet but appears to meet, and the real image is formed when rays of light actually meet. You can understand the concept of the real image with the help of the following diagram.
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(The image displays the concept of real image with the help of positioning of objects)
FAQs on Reflection of Light Image Explained
1. What is the reflection of light, and what are its fundamental laws?
The reflection of light is a phenomenon where light rays bounce off a surface after striking it. It is governed by two fundamental laws:
- The angle of incidence (the angle between the incoming ray and the normal) is equal to the angle of reflection (the angle between the reflected ray and the normal).
- The incident ray, the reflected ray, and the normal to the surface at the point of incidence all lie in the same plane.
2. What is the difference between specular (regular) and diffuse (irregular) reflection?
The primary difference lies in the nature of the reflecting surface. Specular reflection occurs on smooth, polished surfaces like a mirror, where parallel incident rays are reflected as parallel rays, forming a clear image. In contrast, diffuse reflection happens on rough surfaces like a wall or paper. Here, parallel incident rays are scattered in various directions, which allows us to see the object but does not form a distinct image.
3. How is an image formed when light reflects from a surface?
An image is formed at the point where light rays originating from an object appear to converge or actually converge after reflection. If the reflected rays actually intersect at a point, a real image is formed. If the rays only appear to diverge from a point behind the mirror, a virtual image is formed. Our brain traces these diverging rays back to this apparent point of origin, creating the image we perceive.
4. What are the key differences between a real image and a virtual image?
The key differences between a real and a virtual image are:
- Formation: A real image is formed by the actual intersection of reflected (or refracted) light rays, while a virtual image is formed where the rays appear to meet when extended backwards.
- Projection: A real image can be captured and projected onto a screen (like a cinema screen), whereas a virtual image cannot.
- Orientation: Real images formed by single mirrors or lenses are typically inverted (upside down), while virtual images are erect (upright).
- Example: An image formed by a cinema projector is real; the image you see of yourself in a plane mirror is virtual.
5. Why does a plane mirror produce a laterally inverted image?
Lateral inversion is the apparent reversal of left and right. This happens because a plane mirror causes a front-to-back reversal of the object. When you stand in front of a mirror, the light from your right hand travels straight to the mirror and reflects straight back. To your brain, this ray appears to come from a point behind the mirror that is directly in front of your right hand. The same happens for your left hand. This front-back reversal creates the perception that your left and right sides have been swapped in the image.
6. Under what conditions does a concave mirror form a real image versus a virtual image?
The type of image formed by a concave mirror depends entirely on the position of the object relative to its principal focus (F) and centre of curvature (C).
- A real, inverted image is formed when the object is placed anywhere beyond the focal point (F), such as at infinity, beyond C, or at C.
- A virtual, erect, and magnified image is formed only when the object is placed between the pole (P) of the mirror and its principal focus (F). This is the principle used in shaving mirrors and makeup mirrors.
7. Can a convex mirror ever form a real image? Explain why or why not.
No, a convex mirror can never form a real image of a real object. This is because a convex mirror is a diverging mirror. It spreads out the parallel rays of light that strike its surface. The reflected rays always appear to diverge from a focal point located behind the mirror. Since the reflected rays never actually intersect in front of the mirror, they can only form a virtual, erect, and diminished image, regardless of the object's position.
8. What is the importance of using Cartesian sign conventions when studying image formation?
The Cartesian sign convention provides a universal set of rules for assigning positive or negative values to distances (object distance, image distance, focal length) and heights. Its importance is crucial because it allows the mirror formula (1/f = 1/v + 1/u) and the magnification formula to be applied consistently to all types of spherical mirrors (concave and convex) and for all object positions. This system prevents confusion and ensures that calculations correctly predict the nature, position, and size of the formed image.
