Elite Edusphere Institute

Here is every "Must-Know" concept of Light , compressed into one post. 💡📖

1️⃣ THE BASICS
Light: An electromagnetic wave. It travels in a straight line (Rectilinear propagation).

Speed: 3×10⁸m/s in vacuum.

2️⃣ REFLECTION (MIRRORS)
Law: Angle of incidence (i) is ALWAYS equal to the angle of reflection (r).

Concave Mirror: Converging. Used in torches, shaving mirrors, and by dentists.

Convex Mirror: Diverging. Always gives a diminished, erect image. Used as rear-view mirrors in vehicles.

Mirror Formula:

1/f= 1/v + 1/u


3️⃣ REFRACTION (BENDING)
The Cause: Light changes speed when it enters a different medium (e.g., Air to Glass).

Snell’s Law: The ratio "sini/sinr" is constant for a given pair of media (Refractive Index).

Refractive Index (n):

n= c/v


(Speed of light in air / Speed in medium).

4️⃣ LENSES (THE POWER)
Convex Lens: Converging (Think: Magnifying glass).

Concave Lens: Diverging (Think: Correcting Myopia).

Lens Formula:

1/f= 1/v-1/u


Power (P): Measured in Dioptres (D).

P= 1/f (in meters)


5️⃣ DISPERSION (THE PRISM)
Action: White light enters a prism and splits into VIBGYOR (Violet bends the most, Red the least).

Atmospheric Refraction: Why stars twinkle and why we see the sun 2 minutes early!

🧪 MASTER SPECIALIST TIPS:
Sign Convention: Always treat u (object distance) as negative (−).

Magnification (m): If m is negative, the image is Real.
If m is positive, it’s Virtual.

Units: Always convert Focal Length (f) to meters before calculating Power.

SAVE THIS POST for your revision.
SHARE with a classmate who is struggling with Ray Diagrams.

Elite Edusphere Institute
Concept Engineering by EEI.

📐 Trigonometry Made Simple – Class 10.
This is your complete mini-map of the chapter.

Here’s what you really need to understand:

1️⃣ Right Triangle Basics – Every ratio starts here.
Hypotenuse, Opposite, Adjacent → the foundation of all trigonometry.

2️⃣ Trigonometric Ratios – sinθ, cosθ, tanθ
Know what they mean, not just memorize.

3️⃣ Reciprocal Ratios – cosecθ, secθ, cotθ
They are just flips of the main ratios.

4️⃣ Fundamental Identity – sin²θ + cos²θ = 1
Every other formula comes from this.

5️⃣ Standard Angles – 0°, 30°, 45°, 60°, 90°
Remember these visually, they save time in exams.

6️⃣ Complementary Angles – sin(90° − θ) = cosθ, tan(90° − θ) = cotθ
Patterns you can actually see instead of cramming.

7️⃣ Quick Mini Map – Everything connected in one glance
Ratios → Reciprocal → Identity → Angles → Complementary.

💡 Trigonometry is easier when you understand connections, not just memorize formulas.

Save this carousel. Swipe back anytime. Revision made easy.

EEI – Making Maths Visual, Simple, and Student-Friendly.

Electricity was not invented in one day.
It was slowly discovered by curious people asking simple questions.
The first clue came from ancient Greece.
Around 600 BC, a Greek philosopher named
Thales of Miletus
noticed something strange.
When he rubbed amber with fur, the amber started attracting small pieces of straw.
Like magic.
But it was not magic.
It was electric charge.
The word electricity actually comes from the Greek word:
“Elektron” = Amber
For many centuries, people did not understand it well.
Then in the 1700s, a scientist named
Benjamin Franklin
did a famous kite experiment during a thunderstorm.
He proved that lightning is electricity.
This was dangerous. Do NOT try it. 😄
Later, scientists like
Michael Faraday
and
Thomas Edison
made electricity useful for everyday life.
Faraday discovered how to generate electricity using magnets.
Edison built practical electric lighting systems.
So electricity moved from curiosity → technology → civilization.
Today electricity runs:
• lights
• fans
• phones
• hospitals
• internet
• industries
Without electricity, modern life stops.

A student once asked his teacher:
“Sir… when will I ever use Algebra in real life?
I never see x and y anywhere.”
The teacher smiled and said:
“Someday you will earn money.”
Student: “And?”
Teacher:
“Then you will calculate where it all disappeared.”

📘 Unlock the Secret DNA of Numbers! 🔢

★Fundamental Theorem of Arithmetic
Every positive integer greater than 1 can be expressed uniquely as a product of prime numbers (except for the order of factors).

Mathematically:n = p₁ᵃ¹ × p₂ᵃ² × … × pₖᵃᵏ
Where:
p₁, p₂, …, pₖ are prime numbers
a₁, a₂, …, aₖ are positive integers.

★Canonical Decomposition(Standard Form) – It is the process of writing a number as a product of prime powers.
It reveals the prime DNA of any number.

★The 4 Steps to Find Canonical Decomposition:
> Start dividing the number by the smallest prime (2) until it no longer divides evenly.
>Move to the next prime (3, 5, 7…) and repeat.
>Continue until the quotient becomes 1
> Express the number as product of prime powers.

★ Example –
Find canonical decomposition of 180:
🔹 180 ÷ 2 = 90
🔹 90 ÷ 2 = 45
🔹 45 ÷ 3 = 15
🔹 15 ÷ 3 = 5
🔹 5 ÷ 5 = 1.

✅Practice Set – Try Yourself!
1️⃣ Find canonical decomposition of 210
2️⃣ Find canonical decomposition of 360
3️⃣ Find canonical decomposition of 504
(Hint: Follow the 4 steps above!)

★ Real-Life Applications:
✨ HCF & LCM: Quickly find HCF/LCM of numbers using prime factors.
✨ Cryptography: Prime numbers secure online communication.
✨ Engineering & Design: Dividing resources into equal blocks.
✨ Math puzzles & competitions: Speed up calculations effortlessly.

“Every number has a story hidden in primes. Read it, and you can solve HCF, LCM, and unlock the secrets of math!”

Can you find the prime DNA of your age? 🔢
Save this post to never forget the secret building blocks of numbers! ✨

Maths fear usually comes from weak foundations, not low ability.

When concepts are clear,
problems feel lighter.

When thinking is structured,
confidence becomes natural.

It’s a long-term system.