Physics Light Formulas - Science Class 10

Learn important formulas from the Physics Light chapter of Class 10 Science with examples, variables and applications.

📐 Physics Light Formulas

Complete collection of formulas with explanations and examples

Focal Length Radius Relation

$$f = R/2$$

Description: Focal Length Radius Relation is a standard relation used in physics-light.

Example:

Apply the relation: f = R/2

Identify the known values, substitute them in the relation, and solve for the unknown quantity.
Result depends on the substituted values.

Applications:

  • Use this when the quantities in the relation are known and the missing quantity is required.

Lens Formula

$$1/f = 1/v - 1/u$$

Description: Lens Formula is a standard relation used in physics-light.

Example:

Apply the relation: 1/f = 1/v - 1/u

Identify the known values, substitute them in the relation, and solve for the unknown quantity.
Result depends on the substituted values.

Applications:

  • Use this when the quantities in the relation are known and the missing quantity is required.

Lens Magnification

$$m = h_i/h_o = v/u$$

Description: Lens Magnification is a standard relation used in physics-light.

Example:

Apply the relation: m = h_i/h_o = v/u

Identify the known values, substitute them in the relation, and solve for the unknown quantity.
Result depends on the substituted values.

Applications:

  • Use this when the quantities in the relation are known and the missing quantity is required.

Mirror Formula

$$1/f = 1/v + 1/u$$

Description: Mirror Formula is a standard relation used in physics-light.

Example:

Apply the relation: 1/f = 1/v + 1/u

Identify the known values, substitute them in the relation, and solve for the unknown quantity.
Result depends on the substituted values.

Applications:

  • Use this when the quantities in the relation are known and the missing quantity is required.

Mirror Magnification

$$m = h_i/h_o = -v/u$$

Description: Mirror Magnification is a standard relation used in physics-light.

Example:

Apply the relation: m = h_i/h_o = -v/u

Identify the known values, substitute them in the relation, and solve for the unknown quantity.
Result depends on the substituted values.

Applications:

  • Use this when the quantities in the relation are known and the missing quantity is required.

Power of Lens

$$P = 1/f$$

Description: Power of Lens is a standard relation used in physics-light.

Example:

Apply the relation: P = 1/f

Identify the known values, substitute them in the relation, and solve for the unknown quantity.
Result depends on the substituted values.

Applications:

  • Use this when the quantities in the relation are known and the missing quantity is required.

Refractive Index

$$n = sin i / sin r$$

Description: Refractive Index is a standard relation used in physics-light.

Example:

Apply the relation: n = sin i / sin r

Identify the known values, substitute them in the relation, and solve for the unknown quantity.
Result depends on the substituted values.

Applications:

  • Use this when the quantities in the relation are known and the missing quantity is required.

Refractive Index Speed Relation

$$n = c/v$$

Description: Refractive Index Speed Relation is a standard relation used in physics-light.

Example:

Apply the relation: n = c/v

Identify the known values, substitute them in the relation, and solve for the unknown quantity.
Result depends on the substituted values.

Applications:

  • Use this when the quantities in the relation are known and the missing quantity is required.

Quick Reference

Focal Length Radius Relation: $f = R/2$
Lens Formula: $1/f = 1/v - 1/u$
Lens Magnification: $m = h_i/h_o = v/u$
Mirror Formula: $1/f = 1/v + 1/u$
Mirror Magnification: $m = h_i/h_o = -v/u$
Power of Lens: $P = 1/f$
Refractive Index: $n = sin i / sin r$
Refractive Index Speed Relation: $n = c/v$

💡 Worked Examples

Step-by-step solutions using Physics Light formulas

Example 1: Area of Circle

Circle Area Formula
Problem:

Find the area of a circle with radius 7 cm.

Solution:
  1. Given: r = 7 cm
  2. Apply formula: A = πr²
  3. Substitute: A = π × 7²
  4. Calculate: A = π × 49 = 49π cm²
  5. Approximate: A ≈ 49 × 3.14159 ≈ 153.94 cm²
Answer:

Area = 49π cm² ≈ 153.94 cm²

🎯 Practice Problems

Try these problems to test your understanding:

Practice Problem 1

Solve the quadratic equation: x² - 7x + 12 = 0

Practice Problem 2

Find the area of a circle with diameter 14 cm.

Practice Problems

Check Your Formula Recall

Write each formula once, define every variable, then solve one direct substitution problem before moving to mixed questions.

Apply Physics Light

Pick two formulas from this page and create your own values for the variables. Verify units and signs before calculating.

Derivation Notes

Focus on how the formula is built, not only the final expression. Derivations help with board-exam reasoning and multi-step application questions.

  • Start from the definition or identity used in the chapter.
  • Write assumptions clearly before substituting values.
  • Track units through each step to catch calculation mistakes.

Where These Formulas Are Used

Board Exam Problems

Use these formulas for direct numerical questions, proof-based steps, and short-answer reasoning in Science.

Competitive Practice

Memorize the condition of use for each formula so you can identify the right expression quickly under timed practice.

Related Formula Chapters

Chemistry Equations And Relations 3 formulas Physics Electricity 9 formulas Physics Light 8 formulas

These Physics Light formulas help students revise concepts quickly and apply equations accurately in exam-style problems.

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