Cheat sheet for class 10th, Cheat Sheet of Physics

Download Cheat sheet for class 10th and more Cheat Sheet Physics in PDF only on Docsity!

Light- Reflection &

Refraction

- RAPID REVISION -

First watch One Shot

Rapid Revision

Plane mirror : A smooth and polished surface with very few

bumps that reflects light.

The image formed by a plane mirror is :

always virtual and erect.

size of the image is equal to that of the object.

image formed is as far behind the mirror as the object

is in front of it.

image is laterally inverted.

Spherical mirror : a mirror whose reflecting surface is part of a hollow sphere of glass.

reflecting surface is curved inwards, towards the center of the sphere reflecting surface is curved outwards.

CONCAVE MIRROR CONVEX MIRROR

Terms Definition Pole (P) The center point of the reflecting surface of a spherical mirror. Centre of Curvature (C) The center of the sphere of which the mirror's reflecting surface forms a part. Radius of Curvature (R) The radius of the sphere of which the mirror's reflecting surface forms a part. Principal Axis The straight line passing through the pole and the center of curvature of the mirror. Principal Focus (F) The point where parallel rays of light either converge or appear to diverge after reflecting from the mirror. Focal Length (f) The distance between the pole and the principal focus. Aperture The diameter of the reflecting surface of the spherical mirror. R = 2f

CONCAVE

MIRROR

CONVEX

MIRROR

Concave Mirror Convex Mirror Mirror parts ki definitions orr ray diagrams kaafi important h!

Concave Mirror Convex Mirror Uses of Concave Mirrors: Torches, Search-lights, and Vehicle Headlights: Shaving Mirrors Dentist's Mirrors Solar Furnaces Uses of Convex Mirrors: Rear-view Mirrors in Vehicles: Preferred in Vehicles: Provide erect, though diminished, images. Have a wider field of view due to their outward curve. Allow drivers to view a larger area compared to plane mirrors.

Step 1 : Firstly check what question is asking and what values are given. Out of u,v,f two quantities will be given adn you’ll have to find third one. Step 2 : Use the mirror formula for finding the values, (m > 0): image is upright. (m < 0): The image is inverted concave convex Type of Questions asked?

f = always -ve

u = always -ve

v = -ve (real)

= +ve (virtual)

f = always +ve

u = always −ve

v = always +ve (virtual)

from sign of f we can find out

which type of mirror is given

from sign of v we can find out

the nature of image formed by

concave mirror

Step 3 : if about magnification is asked, use this formula:

h = +ve

h′ = +ve (upright, virtual)

= −ve (inverted, real)

h = +ve

h′ = +ve (virtual and upright)

concave convex

from value of ‘m’ we can find out the nature of image formed , from m we can also find the values of h and h’.

also h’ tells about the nature of image, from this we can also get an idea of which type of mirror is present

Refraction of Light

Laws of refraction of light.

(i) The incident ray, the refracted ray and the normal to the

interface of two transparent media at the point of incidence, all

lie in the same plane.

(ii)

Phenomenon of change in the direction of light when it passes from

one transparent medium to another.

Snell’s law of refraction.

Refractive index : measurement of how much a light ray bends when

it passes from one medium to another.

Ray Diagrams

(i) A ray of light from the object,

parallel to the principal axis

(ii) A ray of light passing through a principal

focus

(iii) A ray of light passing through the optical

centre of a lens

One of the most important chapter!

Convex Lens Concave Lens

Important Formulas of Lens: All measurements are taken from the optical centre of the lens. focal length of a convex lens = positive, and that of a concave lens = negative. Lens formula: Magnification: Power of Lens: The ability of a lens to converge or diverge the ray of light after refraction through it is called the power of the lens. It is defined as the reciprocal of focal length. ‘ SI unit = Dioptre (D) 1 dioptre is the power of a lens whose focal length is 1 metre. 1D = 1m. power of a convex lens = positive power of concave lens = negative.

• Formulas yaad rakhna!

Step 1 : Firstly check what question is asking and what values are given. Out of u,v,f two quantities will be given adn you’ll have to find third one. Step 2 : Use the lens formula for finding the values, (m > 0): image is upright. (m < 0): The image is inverted Type of Questions asked?

from sign of f we can find out

which type of lens is present

from sign of v we can find out

the nature of image formed by

convex lens

Step 3 : if about magnification is asked, use this formula:

h = +ve

h′ = +ve (upright, virtual)

= −ve (inverted, real)

h = +ve

h′ = +ve (virtual and upright)

concave convex

from value of ‘m’ we can find out the nature of image formed , from m we can also find the values of h and h’.

also h’ tells about the nature of image, from this we can also get an idea of which type of lens which is present

concave convex

f = always +ve

u = always −ve

v = +ve (real image)

= −ve(virtual image)

f = always −ve

u = always −ve

v = always −ve

screen vaale questions Refractive indexes and speed of light in medium refractive indexes are given of particular medium and speed of light is also then asked what will be the speed of light in those mediums. formula used: a slide projector has lens and other quantities are given. Position of screen is asked that slide projector remains in focus

More Types: