Linear Magnification Formula, Examples & NEET Tricks | Physics Notes

 - Dr.Sanjaykumar Pawar  

Linear Magnification Class 11 Physics: Formula, Solved Questions & Mnemonics

Linear Magnification Explained: Formula, Area Relation, and NEET Problem-Solving Method

 

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Anchor Text: Physics Problem Solving Techniques

Linear Magnification (NEET Study Notes)

Question

Q. The photograph of a house occupies an area of 1.75 cm² on a 35 mm slide. The slide is projected onto a screen, and the area of the house on the screen is 1.55 m².

Find the Linear Magnification of the projector-screen arrangement.

Step-by-Step Solution

Step 1 : Write the Given Data

Quantity	Value
Area on Slide	1.75 cm²
Area on Screen	1.55 m²

Step 2 : Convert m² into cm²

Since 1 m = 100 cm

Therefore, 1 m² = 100 × 100 = 10,000 cm²

Hence, 1.55 m² = 1.55 × 10,000 = 15,500 cm²

Step 3 : Find Area Magnification

Formula

Area Magnification = Image Area / Object Area

= 15,500 / 1.75

= 8857.14

Step 4 : Find Linear Magnification

Area Magnification = (Linear Magnification)²

Linear Magnification

= √8857.14

= 94.1

Answer = 94 ×

Short Notes

What is Magnification?

Magnification tells us how many times bigger or smaller the image is compared to the object.

Types of Magnification

Type	Formula
Linear Magnification	Image Length / Object Length
Area Magnification	Image Area / Object Area

Important Formula

Area Magnification = (Linear Magnification)²

Linear Magnification = √Area Magnification

Unit Conversion

Unit	Conversion
1 m	100 cm
1 m²	10,000 cm²
1 cm²	100 mm²

Golden Rule

Always convert all units into the same unit before applying any formula.

Question Solving Flow

Question
↓
Convert Units
↓
Area Magnification
↓
Take Square Root
↓
Linear Magnification

Mnemonics & Memory Tricks

Mnemonic 1

AREA → ROOT → LENGTH

If Area is given, take the Square Root to get Linear Magnification.

---

Mnemonic 2

ADR Rule

• A = Area
• D = Divide
• R = Root

Remember only ADR and solve the complete question.

---

Mnemonic 3

Square means Area. Whenever you see cm² or m² think Square Root for Linear Magnification.

Common Mistakes

• Not converting m² into cm².
• Using Length Formula instead of Area Formula.
• Taking Square Root before dividing.
• Ignoring unit conversion.

NEET Exam Trick

Whenever the question contains Area remember

Convert → Divide → Root → Answer

10 Second Revision Card

Area
↓
Convert Unit
↓
Divide
↓
Square Root
↓
Linear Magnification