⚡ Class 10 Physics – Chapter 1: Electricity | Notes, Formulas, and Concepts

 Welcome Class 10 students! Here's your complete, easy-to-understand blog-style guide to CBSE Physics Chapter 1 – Electricity. It covers definitions, formulas, SI units, laws, and numerical tips to ace your exams confidently. 🧠📘

🔌 What is Electricity?

Electricity is the flow of electric charge (electrons) through a conductor, like copper wire.

Electric Current (I):
The amount of charge (Q) flowing through a conductor in 1 second.

Formula:
I = Q / t
Where:

  • I = current (Ampere, A)

  • Q = charge (Coulomb, C)

  • t = time (seconds)

🔋 Potential Difference (V)

It is the work done to move a unit charge from one point to another.

Formula:
V = W / Q
Where:

  • V = potential difference (Volts, V)

  • W = work done (Joules, J)

  • Q = charge (Coulomb, C)

Instrument Used: Voltmeter (always connected in parallel)

🔥 Ohm’s Law

The electric current flowing through a conductor is directly proportional to the potential difference, provided temperature remains constant.

Formula:
V = I × R
Where:

  • V = potential difference

  • I = current

  • R = resistance (Ohms, Ω)

🔄 Resistance (R)

It is the property of a conductor to oppose the flow of current.

Factors affecting resistance:

  • Length (R ∝ L)

  • Area (R ∝ 1/A)

  • Nature of material

  • Temperature

SI Unit: Ohm (Ω)

🧮 Resistors in Series and Parallel

🔸 Resistors in Series:

  • R_total = R1 + R2 + R3

  • Current is same, voltage divides.

🔹 Resistors in Parallel:

  • 1/R_total = 1/R1 + 1/R2 + 1/R3

  • Voltage is same, current divides.

💡 Electric Power (P)

The rate at which electrical energy is consumed or generated.

Formulas:

  • P = V × I

  • P = I² × R

  • P = V² / R

SI Unit: Watt (W)

1 kW = 1000 W

⚡ Electrical Energy

Formula:
Energy = Power × Time

SI Unit:
Joule (J)
Commercial Unit: kWh (kilowatt-hour)

1 kWh = 1000 × 60 × 60 = 3.6 × 10⁶ J

🔍 Key Instruments

InstrumentPurpose
AmmeterMeasures current (in series)
VoltmeterMeasures voltage (in parallel)
RheostatVaries resistance
GalvanometerDetects current direction

🧠 Extra Tips:

  • Electric Fuse: A safety device that melts and breaks the circuit if current exceeds a certain limit.

  • Good Conductors: Silver, copper

  • Insulators: Rubber, plastic

📌 Important Questions (with answers)

Q1. State Ohm’s Law.
A: Ohm’s Law states that V ∝ I or V = I × R at constant temperature.

Q2. What happens to resistance if the wire length is doubled?
A: Resistance becomes twice (R ∝ L).

Q3. Calculate current if V = 12V and R = 3Ω.
A: I = V/R = 12/3 = 4 A

Q4. Power consumed by a device with 10A current and 220V supply?
A: P = V × I = 220 × 10 = 2200W or 2.2 kW

✅ Summary:

QuantitySymbolSI UnitFormula
Electric CurrentIAmpere (A)I = Q/t
Potential DifferenceVVolt (V)V = W/Q
ResistanceROhm (Ω)V = IR
PowerPWatt (W)P = VI, P = I²R, V²/R
EnergyEJoule (J)E = P × t

Comments

Post a Comment

Popular posts from this blog

📘 Class 10 History Chapter 1: The Rise of Nationalism in Europe – Notes

✨ Introduction The chapter explains how the idea of nationalism emerged in Europe after the French Revolution and how it led to the formation of nation-states like Germany, Italy, and Greece. 🪄 Key Concepts 🔹 1. French Revolution and the Idea of Nation The French Revolution of 1789 introduced liberty, equality, fraternity . Nationalism began with: Abolition of monarchy Introduction of a constitution Creation of national symbols (flag, national anthem) Terms like La Patrie (the fatherland) and Le Citoyen (the citizen) were used. French army spread revolutionary ideas to other parts of Europe. 🔹 2. The Making of Nationalism in Europe Europe in the 19th century had many states with diverse cultures, languages, and rulers. No nation-states yet; regions ruled by monarchies like Habsburg Empire. Liberal Nationalism meant: Freedom of individuals Equal laws Free market (economic liberalism) 🔹 3. The Age of Revolutions: 1830–1848 ...
Read more

🌍 Class 10 Geography – Chapter 1: Resources and Development-Notes

Image
Welcome Class 10 students! Here are your complete, easy-to-understand notes for Geography Chapter 1 – Resources and Development . Perfect for revision, exams, or your school blog! ✅ What is a Resource? Anything that is technologically accessible, economically feasible, and culturally acceptable is called a resource. 🔹 Examples : Water, forests, minerals, solar energy, etc. 🧭 Types of Resources 🔹 Based on Origin Biotic : Living things (plants, animals, humans) Abiotic : Non-living things (air, water, soil, minerals) 🔹 Based on Exhaustibility Renewable : Can be regenerated (sunlight, wind) Non-renewable : Limited, can’t be reused (coal, petroleum) 🔹 Based on Ownership Individual : Privately owned land or buildings Community : Public parks, ponds, playgrounds National : Roads, railways, public buildings International : Oceans, airspace beyond 200 nautical miles 🔹 Based on Development Potential : Available but unused Developed : Explored and in use ...
Read more

🧪 Class 10 Chemistry Chapter 2: Acids, Bases, and Salts –Notes

  Welcome back, Class 10 students! Let’s dive into the world of acids, bases, and salts — one of the most important and interesting chapters in your Chemistry syllabus. This chapter explains what acids and bases are, how they behave, and how salts are formed. Plus, we'll explore real-life examples and reactions! 🔍 What Are Acids and Bases? 📌 Acids Acids are substances that taste sour and release H⁺ ions in aqueous solution. Examples: Hydrochloric acid (HCl) Sulphuric acid (H₂SO₄) Citric acid (in fruits) 📌 Bases Bases are substances that taste bitter and release OH⁻ ions in aqueous solution. Examples: Sodium hydroxide (NaOH) Magnesium hydroxide (Milk of Magnesia) Ammonium hydroxide (NH₄OH) 🧪 Indicators – Acids vs. Bases Indicators help detect acids or bases by changing colour. Indicator Acid Colour Base Colour Litmus Red Blue Methyl Orange Red Yellow Phenolphthalein Colourless Pink China Rose (Natural) Dark Pink Green ⚗️ Reactions of Acids...
Read more