CBSE Class 10 Science Notes Chapter 12 Electricity

Electricity class 10 notes offer a comprehensive overview of how electric charges flow through conductors to power various devices. These notes cover fundamental concepts like electric current, potential difference, and Ohm’s Law. By using these resources, you can master circuit diagrams and mathematical formulas, ensuring you are well-prepared for your board exams and competitive tests.

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Electricity Class 10 Notes

Electricity Class 10 Notes provide a concise explanation of important concepts such as electric current, Ohm’s Law, resistance, electric power, and energy for easy understanding.

These notes are designed for quick revision and help students prepare effectively for CBSE exams with key formulas and numericals.

1. Fundamentals of Electric Charge and Current

Electric Charge (Q)

At its most basic level, electricity begins with the concept of electric charge. There are two types of electric charges: positive and negative.

• Fundamental Principles: Like charges repel each other, while unlike charges attract each other.

• SI Unit: The SI unit of electric charge is the Coulomb (C).

• Fundamental Charge: The smallest independent charge is the charge of a single electron, denoted by e, which is approximately 1.6 × 10⁻¹⁹ C.

Electric Current (I)

Electric current is defined as the rate of flow of positive electric charge through a conductor.

• Formula:
  
  where I is current, Q is charge, and t is time.
  
  

• SI Unit: The SI unit of electric current is the Ampere (A).

• Direction of Current: By convention, the direction of electric current is taken as opposite to the direction of flow of electrons.

• Measurement: Electric current is measured using an Ammeter, which is always connected in series in a circuit.
  
  

Potential Difference and Resistance

Potential Difference (V)

Potential difference (also called voltage) between two points in an electric circuit is defined as the amount of work done in moving a unit charge from one point to another.

• Formula:
  
  where W is the work done (in joules) and Q is the charge.
  
  

• SI Unit: The SI unit of potential difference is the Volt (V).

• Flow Direction: Conventional current flows from a point of higher potential to lower potential, whereas electrons flow from lower potential to higher potential.

• Measurement: Potential difference is measured using a Voltmeter, which is connected in parallel across the component.

Resistance (R) and Resistivity (ρ)

Resistance is the property of a conductor that opposes the flow of electric current through it.

Factors Affecting Resistance

1. Length (L): Resistance is directly proportional to the length of the conductor
   

2. Area of Cross-section (A): Resistance is inversely proportional to the cross-sectional area
   

3. Material: Different materials have different resistance depending on their nature.

4. Temperature: In metals, resistance generally increases with an increase in temperature.
   
   

Resistivity (ρ)

Resistivity is a characteristic property of a material and does not depend on the length or area of the conductor. Materials like metals have low resistivity, while insulators such as rubber and glass have very high resistivity.

• SI Units:
  
  

• Resistance → Ohm (Ω)

• Resistivity → Ohm-metre (Ω m)

Ohm’s Law

Ohm’s Law states that the potential difference (V) across the ends of a metallic conductor is directly proportional to the current (I) flowing through it, provided the temperature remains constant.

• Mathematical Expression:
  

• Graphical Representation:
  A V–I graph for an ohmic conductor is a straight line passing through the origin. The slope of this graph represents the resistance (R) of the conductor.

Combinations of Resistors

In electric circuits, resistors are commonly connected in series or parallel.

Series Combination

In a series combination, resistors are connected end-to-end so that the same current flows through each resistor.

• Equivalent Resistance:

• Key Property:
  The current remains the same throughout the circuit, but the total potential difference is divided among the resistors.
  
  

Parallel Combination

In a parallel combination, resistors are connected across the same two points, providing multiple paths for current flow.

• Equivalent Resistance:
  

Advantages of Parallel Combination

1. Independence: If one appliance fails, the others continue to work.
   
   

2. Specific Current Requirement: Different devices can draw different amounts of current as needed.
   
   

3. Reduced Resistance: The total resistance of the circuit is less than the smallest individual resistance, making it more efficient.
   
   

Electric Power

Electric power (P) is the rate of consuming electric energy. The SI unit of power is Watt (W).

P = VI

Electric energy (E) supplied by a source is E = P x t. The commercial unit of energy is kilowatt-hour (kWh).

Heating Effect of Electric Current

When current passes through a conductor, it heats up. This is the heating effect of electric current.

Joule’s Law of Heating

According to Joule’s law, the heat produced (H) in a resistor is:

1. Directly proportional to the square of the current (I²).

2. Directly proportional to the resistance (R).

3. Directly proportional to the time (t) for which current flows.
   
   

• Formula:
  

Applications of Heating Effect

Practical Applications of Heating Effect

• Electric Appliances: Devices like electric irons, heaters, kettles, and ovens work on the heating effect of electric current.

• Electric Bulbs: The filament, usually made of tungsten due to its high melting point, becomes white-hot and emits light.

• Electric Fuse: A fuse is a safety device made of a wire with a low melting point. It melts when excessive current flows, breaking the circuit and preventing damage to appliances and fire hazards.

Circuit Symbols

Electrical components are shown using specific symbols in circuit diagrams.

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How Electricity Moves in Wires

In our electricity class 10 notes, we say that electric current is just charges moving through a wire. Think of it like water flowing through a pipe. The faster the charges move, the higher the current. Even though tiny electrons move one way, we always draw the current moving the opposite way.

Tools to Measure Electricity

• Ammeter: A small tool used to see how much current is flowing. You put it right in the path of the electricity.

• Voltmeter: A tool used to measure the push (voltage) between two points. You put it next to the wire.

• The Ampere: This is just the name we use to count the flow, like how we use liters for water.

The Push Behind the Flow

Charges do not move by themselves. They need a push from a battery or a cell. This push is called the potential difference. If there is no push, the light bulb will not glow. This is a big part of electricity class 10 notes questions and answers.

The Rule of Ohm and Friction

There is a famous rule called Ohm’s Law. It is the most important part of any electricity class 10 notes pdf. It says that if you give a bigger push (voltage), you get more current. This only works if the wire does not get too hot.

What is Resistance?

Resistance is like friction for electricity. It tries to stop the charges from moving.

• The Ohm ($\Omega$): This is the unit we use to measure this friction.

• Good Conductors: Metals like copper have very low friction, so electricity flows fast.

Why Does Resistance Change?

According to electricity class 10 notes prashant kirad, four things change how hard it is for electricity to move:

1. Length: A longer wire makes it harder for electricity to get through.

2. Thickness: A thick wire is like a wide road; it makes it easier for electricity to move.

3. Material: Some materials are just naturally better at carrying current.

4. Heat: When a wire gets hot, it usually becomes harder for electricity to flow.

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Joining Different Bulbs and Wires

Sometimes we want to connect many bulbs together. How we join them changes how the circuit works. This is a top topic in electricity class 10 notes questions and answers.

One After the Other (Series)

In a series circuit, bulbs are joined in one single line.

• The Current: It stays the same in every bulb.

• The Problem: If one bulb breaks, all the other bulbs will turn off too.

• Total Friction: The total resistance is just all of them added up.

Side by Side (Parallel)

In a parallel circuit, each bulb has its own separate path.

• The Voltage: Each bulb gets the same full push from the battery.

• The Benefit: If one light goes out, the others stay on. This is why electricity class 10 notes in hindi and English say we use this in our homes.

When Wires Get Very Hot

When electricity struggles to move through a wire with high friction, the wire gets very hot. We call this the heating effect. We use this heat every day in our kitchens and bathrooms.

Joule’s Heating Rule

This rule says that the amount of heat depends on:

• How much current you use (more current = way more heat).

• How much friction the wire has.

• How long you keep the switch on.

How We Use This Heat

1. Electric Heaters: They use special wires that get red hot to warm our rooms.

2. Light Bulbs: The tiny wire inside gets so hot that it starts to glow and give us light.

3. The Fuse: This is a safety wire. If too much electricity flows, it melts and cuts the power so your house does not catch fire.

Power and Your Electric Bill

The last part of the electricity class 10 notes is about power. Power is just a way to say how fast an appliance uses up energy. A big heater uses energy faster than a tiny LED bulb.

Simple Power Math

You can find out the power of a tool by multiplying the push (voltage) by the flow (current).

• The Watt: This is the unit for power. A 100-watt bulb uses more energy than a 10-watt bulb.

Paying for Electricity

The electric company does not count every tiny bit of energy. They use a big unit called the Kilowatt-hour (kWh).

• One Unit: When you use a 1000-watt heater for one hour, that is one unit on your bill.

• Exam Help: When you use an electricity class 10 notes pdf, always practice the math problems about calculating the cost of using fans and lights.

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Electricity Class 10 Notes: FAQs

1. What is an electric circuit?

It is a closed loop or path made of wires that lets electricity flow from a battery to a bulb and back.

2. What is an insulator?

An insulator is a material like rubber or plastic that does not let electricity move through it at all.

3. Why do bulbs have thin wires?

Thin wires have more friction (resistance). This helps them get hot enough to give off light.

4. What does a battery do?

A battery acts like a pump. It gives the electricity the "push" it needs to start moving through the wires.

5. Is air a conductor?

No, air is usually a very good insulator. If it weren't, electricity would jump out of the sockets and hit us!