CBSE Notes Class 10 Science Chapter 12 - Magnetic Effects of Electric Current

Magnetic Effects of Electric Current is a fundamental concept in physics that explain how electricity and magnetism are closely connected, forming the foundation of many modern technologies such as electric motors, generators, and electromagnets. When an electric current flows through a conductor, it produces a magnetic field around it—a principle first observed by scientists and later developed into laws and applications used in daily life. These concepts help learners understand the behavior of current-carrying conductors, magnetic fields, Fleming’s rules, and electromagnetic induction in a clear and logical way.

CBSE Notes Class 10 Science Chapter 12 – Magnetic Effects of Electric Current are designed to present these ideas in a simplified, exam-oriented format based strictly on the latest CBSE syllabus. These notes cover all key definitions, laws, diagrams, and numerical concepts required for board exams, while also supporting conceptual clarity. These magnetic effect of electric current class 10 notes support quick revision, strengthen numerical problem-solving skills, and align perfectly with the latest CBSE syllabus and board exam pattern, making them an essential resource for effective preparation.

1.0Download CBSE Notes for Class 10 Science Chapter 12: Magnetic Effects of Electric Current - Free PDF!!

Download Free CBSE Class 10 Science Chapter 12: Magnetic Effects of Electric Current Notes PDF to revise electromagnetism, Fleming’s rules, electromagnetic induction, motors, generators, and key numericals with clear, exam-oriented explanations aligned to the CBSE syllabus.

2.0Oersted’s Experiment

• They found that a compass needle is deflected when an electric current travels through a metallic wire placed nearby.
• Observations show that electricity and magnetism were related phenomena.
• It is established that there are two sources of magnetism namely, electric current and permanent magnet.

3.0Magnetic Field and Magnetic Field Lines

• Magnetic Field: The magnetic field is the area around a magnet where its influence affects other magnetic materials. It is measured in Teslas (T).
• Magnetic Field Lines: These lines extend from the north pole of a magnet, curve around, and return to the south pole  forming closed loops. They are densest near the poles and never intersect. The direction of the magnetic field at any point is indicated by the tangent to the field lines at that point.

4.0Magnetic Field around a Current Carrying Straight Conductor

When an electric current transfers through a straight conductor, it generates a magnetic field around it, which is invisible but can be detected with a magnetic compass. Increasing the current causes greater deflection of the compass needle. The magnetic field lines form concentric circles centred on the wire and lie in a plane perpendicular to its length. The field strength is stronger near the conductor and weakens with distance from it.

Right Hand Thumb Rule

The Right-Hand Thumb Rule identifies the direction of the magnetic field around a current-carrying conductor. To use it:

• Hold the wire with your right hand.
• Point your thumb in the direction of the current.
• Your curled fingers show the direction of the magnetic field lines, which form concentric circles around the wire.

5.0Magnetic Field Around a Circular Conductor with Electric Current

• The magnetic field formed by a current-carrying wire at a specific point is directly proportional to the amount of current flowing through it.
• If a circular coil has n turns, the magnetic field it produces is n times greater than the field generated by a single turn

6.0Magnetic Field established by Current Flowing Through a Solenoid

A solenoid is a coil consisting of numerous circular loops of insulated copper wire wound closely in a cylindrical shape. One end acts as the magnetic north pole and the other as the south pole. Inside the solenoid, the magnetic field lines are parallel and straight, indicating a uniform magnetic field throughout its interior.

7.0Force on a Current Conveying Conductor in a Magnetic Field

•  A current conveying conductor placed in a magnetic field experiences a force that is right angled to both the direction of the current and the magnetic field.
• The direction of the force changes when the current direction in the conductor is reversed.

Fleming Left Hand Rule

It dictates the force direction on a current-carrying conductor in a magnetic field.

• Hold your left hand with the first finger, second finger, and thumb perpendicular to each other. 
• Align the first finger with the magnetic field direction, point the second finger in the current direction, and your thumb will show the direction of the force on the conductor.

8.0Domestic Electric Circuits

• Electric power to a house is supplied via overhead wires or underground cables with three insulated wire
• Live Wire (Brown or Red): Delivers current to the house.
• Neutral Wire (Light Blue or Black): Returns current and is at zero potential.
• Earth Wire (Green or Yellow): Grounds the system for safety.
• The voltage between the live and neutral wires is 220V. At the substation, the neutral and earth wires are connected to ensure they are at the same potential.
• Before entering the house, the supplier installs a fuse in the live wire, rated according to the house's load. The power then passes through an energy meter, which records usage in kilowatt-hours (kWh), with its earth wire grounded locally.
• The meter’s power lines connect to a distribution board that routes electricity through fuses to different parts of the house. Typically, one circuit has a higher current rating for heavy appliances like geysers and air coolers, while another has a lower rating for lights and fans.
• Appliances are connected in parallel across the live and neutral wires, each with its own switch. This ensures each appliance gets a consistent 220V and can operate independently.
• An electric fuse protects the circuit by breaking it if the current exceeds safe levels, melting due to Joule heating to prevent damage.
• Short Circuit-A short circuit occurs when electric current flows through an unintended low-resistance path, typically due to a direct connection between the live and neutral wires.
• Overloading-Overloading happens when too many appliances are connected to a single circuit or when appliances exceed the circuit's current capacity.

9.0Detailed CBSE Class 10 Science Chapter 12 – Key Notes

Permanent Magnets

A solid of any shape or size which can attract pieces of materials like iron, cobalt, nickel is called magnet.

Magnetic poles

• The parts of a magnet where the magnetic force is strongest are called the magnetic poles.
• All known magnets have two poles, a north pole and a south pole.

Properties of a magnet

A magnet has maximum attracting power at poles and minimum at center

A freely suspended bar magnet always points towards north and south direction

A magnet always have two poles north and south pole

When magnetic material comes in contact with magnet, it also get attractive property of magnet

Types Of Magnets

Natural Magnets

Natural occurring minerals or ores having magnetic properties are called 'natural magnets'.

Due to their irregular shapes and weak attracting power, natural magnets are rarely used now a days.

Artificial Magnets

Now a days pieces of iron and many other materials of suitable shapes and sizes are made as magnets. Such magnets are called artificial magnets

Magnetic field

A region of influence surrounding a magnet, in which other magnets or materials like iron are affected by magnetic forces is called 'magnetic field'.

Magnetic field lines

Magnetic field lines represent the magnetic field of a magnet. These lines describe the direction of the magnetic force.

Uses of magnets and electromagnets

• They are used in radio and stereo speakers.
• They are used in almirah and refrigerator doors to keep them in closed position.
• They are used on video and audio cassette tapes.
• They are used on the hard discs and floppies for computers.
• They are used in different children's toys.

Electric current as a source of magnetism

Apart from permanent magnets, electric current is also a source of magnetism.

Oersted, by performing experiments, concluded that 'moving charges or electric currents produce a magnetic field in the surrounding space'.

Magnetic field due to a current-carrying straight conductor

The magnetic field lines around a straight current-carrying conductor are concentric circles with the conductor located at their centre. The plane of these concentric field lines is perpendicular to the conductor.

'moving charges or currents produce a magnetic field in the surrounding space'.

Right hand thumb rule

'Imagine that you are holding a current-carrying straight conductor in your right hand and the thumb is stretched along the direction of current, then your fingers will wrap around the conductor in the direction of the field lines of the magnetic field.'

Magnetic field due to a current-carrying circular loop

Let us take a conducting wire in the form of circular loop and an electric current is flowing through it. At every point of the loop, the magnetic field lines are in the form of concentric circles surrounding the loop.

The right hand thumb rule is also called Maxwell's corkscrew rule (or right hand screw rule). If a right-handed screw moves forward in the direction of the conventional current then the direction of rotation of the screw gives the direction of the magnetic field lines.

Magnetic field of a current-carrying solenoid

If a long, straight conducting wire is bent into a coil of several closely spaced loops, the resulting device is a solenoid. This device acts as a magnet only when it carries a current.

A solenoid is a long insulated wire wound in the form of a helix where neighbouring turns are closely spaced.

Force on current-carrying conductor in magnetic field

An electric current flowing through a conductor produces a magnetic field in a surrounding space and exerts a force on a magnet placed near it. French scientist Andre Marie Ampere suggested that the magnet must also exert an equal and opposite force on the current-carrying conductor.

• Magnetic force on a current-carrying straight conductor is given by,

F = IlB sin θ

• Fleming's left-hand rule

According to this rule, 'stretch the thumb, forefinger and central finger of your left hand such that they are mutually perpendicular. If the fore finger points in the direction of magnetic field and the central finger in the direction of current, then the thumb will point in the direction of motion or the force acting on the conductor.'

Alternating current (AC)

• The electric current, whose magnitude varies with time and direction reverses periodically, provided its amplitude is constant is called 'alternating current'.
• In India, the frequency of AC is 50 Hz.

Direct current (DC)

• The electric current, whose magnitude and direction do not vary with time is called 'direct current'. Usually DC is produced by a cell or a battery. The frequency of pure DC is zero always.

Advantages of AC over DC

• AC voltages can be easily increased (step up) or decreased (step down) with the help of transformers.
• Long distance transmission takes place at high voltage (i.e., less current) to minimise heat losses. This is done easily by using AC voltage because an AC voltage can easily be increased by using a transformer.
• The cost of generation of AC is less than that of DC.
• AC devices are simple, robust and require less care as compared to DC devices.

Disadvantages of AC over DC

• AC is more dangerous than DC.
• A device operating at 220 V AC has to sustain a peak value of approximately 310 V.
• For processes like electrolysis or electroplating, AC cannot be used, only DC can be used.

Domestic electric circuits

(1) One wire of power supply is called live wire (or positive) which has usually a red insulation cover. wire, with black insulation cover is called neutral wire (or negative).

Overloading

Overloading is a condition in which excessively high current flows through a circuit.

Overloading can occur in many ways:

(1) When the live wire and the neutral wire come into direct contact, the resistance in the circuit becomes very low and the current in the circuit abruptly increases. This is called short-circuiting.

(2) Overloading can also occur due to an accidental hike in the supply voltage.

(3) Sometimes, overloading is caused by connecting too many devices to a single socket.

An electric fuse prevents the electric circuit and the appliance from a possible damage by stopping the flow of unduly high electric current.

Electromagnet

An electromagnet is a coil of wire wrapped around a soft iron core. When an electric current flows through the coil, it creates a magnetic field.

Factors affecting strength of electromagnets

Current in the coil
The greater the current flow, the greater the field strength. Strength varies directly as the current in the coil.

Number of turns in the coil
The greater the number of coils, the greater the field strength.

Size of coil
The smaller the diameter of the coil, the stronger the magnetic field.

Type of material in the coil or solenoid
The more ferromagnetic the material within the coil, the greater the magnet's strength. Iron is one of the best materials to use.

10.0Benefits of CBSE Notes for Class 10 Science Chapter 12 - Magnetic Effects of Electric Current

• Formulae and Derivations at a Glance: Important formulas related to magnetic force and induced current are usually compiled in the notes, making them easy to recall and apply.
• Practice Questions and Solutions: Some comprehensive notes may even include sample questions and their solutions, allowing you to test your understanding and prepare for different question formats.
• Improved Retention: By presenting information in a structured and organised way, CBSE Notes can help in better understanding and long-term retention of the concepts.
• Time-Saving: Using notes saves valuable study time as you don't need to underline or extract key information from the textbook yourself.
• Exam-Oriented Approach: The notes are typically designed keeping the CBSE Class 10 syllabus and exam pattern in mind, ensuring you focus on what's important for scoring well.

Also Read:-