Light- Reflection & Refraction is a very important chapter in class 10th for scoring perspective as well as learning perspective. Class 10th science is very important, and if you want to pursue your career in the technical field, and “light: reflection and refraction” is crucial for your strong base.
Definition: We can define Light as a form of energy that helps us to see things. When a luminous object’s light, hits any object and jumps back, which are recognized by our eyes which gives signals to our brain, and our brain processes this signal, and that’s how we see things.
[PDF] Download Class 10th notes, Chapter Light: Reflaction and Refraction
Law of Reflection:
- ∠i=∠r
- In law of Reflection, the incident ray, normal & reflected ray all lie in the same plane.
Curved Mirrors:
- Concave mirror
- Convex mirror
- Pole:- Centre of Spherical mirror (P)
- Centre of Curvature (c): Centre of curvature is the center of the spherical mirror because the mirror is the part of a circle.
- The radius of Curvature (R): Radius of curvature is the distance between pole (P) & center of curvature.
- Principle Axis: Principle Axis is a straight line passing through pole (P) & the Centre of Curvature.
- Principle Focus: A no. of rays passes from the principal axis after reflection, and the meeting point (in the case of Convex mirrors, they appear to be meat) is called the principal focus.
- Focal length: Distance between pole(P) and focal point (f). R =2f.
- Aperture: Diameter of mirror.
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Concave and Convex mirror image Formation chart for class 10th science
Concave mirror
| Position of the object | Position of the image | Size of the image | Nature of the image |
| At Infinity | At the focus(f) | Point Size (Highly diminished) | Real and inverted (upside down) |
| Beyond c | Between Focus(f) and curvature(c) | Small size | 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 |
Convex mirror
| Position of the object | Position of the image | Size of the image | Nature of the image |
| At Infinity | At f (Behind the mirror) | Point Size | Virtual and Erect |
| Between Infinity and pole | Between P and f (behind the mirror) | Small Size | Virtual and Erect |
Uses of Concave and convex mirror:
The concave mirror uses:
- A concave mirror is used in Torches.
- It is used in Searchlights.
- It is used in vehicle headlights.
- Concave mirror is used as Shaving mirrors.
- This mirror is used by doctors.
- It is also used in solar furnaces.
Convex mirror Uses:
A convex mirror is used as a rear view mirror in bikes and cars.
Mirror formula for class class 10th science:
1/f =1/v + 1/v
f= focal length
u= object’s distance from mirror
v= image distance
Magnification
= (height of Image)/(height of object)= h’/h
Refraction
When light travels from one medium to another, its direction changes. This phenomenon is known as refraction. It is caused because of a change in the speed of light as it enters from one medium to another.
Case (i): When a light goes from rarer to a denser medium, it bends towards normal.
Case (ii): When a light goes from denser to rarer medium, it bends away from normal.
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Laws of Refraction
- Incident Ray, Reflected ray, and normal lies in the same plane.
- The ratio of the Sine angle of incidence to the sine angle of refraction is a constant for a given pair of media. This is known as Snell’s Law of Refraction.
Lens– Concave and convex lens
Concave Lens: Diverging lens
Convex Lens: Converging lens
Terms related with Concave and convex lens required for class 10th students
- Centre of Curvature: Lens has two centers of curvature.
- Principal axis: The principal axis is a line passing through the center of Curvature.
- Optical center: Optical center is a point that lies on the principal axis through the rays of light passes without any deflection.
- Principle focus: Principle focus is the point on the Principle axis of a lens or mirror to which parallel rays of light converge or from which they appear to diverge after refraction or reflection.
- Focal Length(f): Focal length is the distance between the center of the lens and the principal focus.
Concave and Convex lens image formation chart
Convex Lens
| Position of the Object | Position of the Image | Size of the Image | Nature of the Image |
| At infinity | At focus (f2) | Point Size (Highly diminished) | Real and Inverted |
| Beyond C | Between f2 and C2 | Smaller than the object | Real and Inverted |
| At C1 | At C2 | Same size as the object | Real and Inverted |
| Between C1 and F1 | Beyond C2 | Enlarged | Real and Inverted |
| At F1 | At infinity | Infinitely large and Highly enlarged | Real and Inverted |
| Between F1 and O | On the same side of the lens as the object | Enlarged | Virtual and erect |
Concave lens
| Position of the Object | Position of the Image | Size of the Image | Nature of the Image |
| At infinity | At F1 | Point size | Virtual and erect |
| Between Infinity and Optical centre | Between F1 and O | Smaller than the object | Virtual and erect |
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