NCERT Class 10 Science Chapter 12 – Magnetic Effects of Electric Current

NCERT Class 10 Science Chapter 12 explains the relationship between electricity and magnetism. In NCERT Class 10 Science Chapter 12, students study magnetic fields, magnetic field lines, force on a current-carrying conductor and domestic electric circuits. NCERT Class 10 Science Chapter 12 is an important physics chapter for CBSE board exams because it connects electric current with magnetism.

NCERT Class 10 Science Chapter 12 begins with the concept of a Magnetic Field, which is the region around a magnet where its force can be experienced. Magnetic field lines emerge from the North Pole and enter the South Pole. The closeness of field lines indicates the strength of the magnetic field.

A major section of NCERT Class 10 Science Chapter 12 discusses the Magnetic Field due to a Current-Carrying Conductor. When current flows through a straight conductor, circular magnetic field lines are formed around it. The direction of the magnetic field is determined by the Right-Hand Thumb Rule.

NCERT Class 10 Science Chapter 12 further explains magnetic fields due to:

• A Straight Conductor
• A Circular Loop
• A Solenoid

A solenoid produces a magnetic field similar to a Bar Magnet, with distinct north and south poles. The magnetic field inside a solenoid is strong and nearly uniform.

Another important concept in NCERT Class 10 Science Chapter 12 is the Force on a Current-Carrying Conductor. When a conductor carrying current is placed in a magnetic field, it experiences a force. The direction of this force is given by Fleming’s Left-Hand Rule. This principle is used in the working of an Electric Motor.

NCERT Class 10 Science Chapter 12 also covers Domestic Electric Circuits. In Indian households, the supply voltage is approximately 220 V. Appliances are connected in Parallel Combination. Safety devices such as Fuses and Earthing are used to prevent electric shock and overloading.

NCERT Class 10 Science Chapter 12 is highly important for CBSE board exams because conceptual and application-based questions from magnetic fields and Fleming’s rules are frequently asked.

Students should refer to the official NCERT website at for authentic textbooks and syllabus updates.

For structured preparation of NCERT Class 9–12 for UPSC, BPSC and State PCS examinations, strengthen your basics with our complete NCERT Book Notes PDF for Class 9-12, available inside the NCERT foundation course level-2.

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12.1 Magnetic field and field lines

• A Magnetic Field is the region around a magnet where its magnetic force can be felt.
• The presence of a magnetic field is detected using a small Compass Needle, which gets deflected.
• Magnetic field lines represent the direction and strength of the magnetic field.
• Outside the magnet, field lines emerge from the North Pole and enter the South Pole.
• Inside the magnet, field lines move from South to North, forming closed continuous loops.
• The closeness of field lines indicates the Strength of the Magnetic Field; closer lines mean stronger field.
• Magnetic field lines never intersect each other because at a point there can be only one direction of the magnetic field.

12.2 Magnetic field due to a current-carrying conductor

• An electric current flowing through a conductor produces a Magnetic Field around it.
• The presence of this magnetic field can be detected by the deflection of a Compass Needle placed near the conductor.
• The magnetic field around a current-carrying conductor consists of Concentric Circular Field Lines.
• The direction of magnetic field depends on the Direction of Current flowing through the conductor.
• If the direction of current is reversed, the direction of the magnetic field also reverses.
• The strength of the magnetic field increases with increase in the Magnitude of Current.
• The magnetic field strength decreases as the distance from the conductor increases.

12.2.1 Magnetic Field due to a Current through a Straight Conductor

• When electric current flows through a Straight Conductor, it produces a magnetic field around it.
• The magnetic field lines are Concentric Circles centred on the conductor.
• The direction of magnetic field can be observed using a Compass Needle placed at different points around the conductor.
• If the current flows upward, the magnetic field lines circulate in one direction; if the current is reversed, the direction of field lines also reverses.
• The strength of the magnetic field is greater near the conductor and decreases as the Distance from the Conductor increases.
• Increasing the Magnitude of Current increases the strength of the magnetic field.
• The pattern of magnetic field lines demonstrates that electric current produces magnetism.

12.2.2 Right-Hand Thumb Rule

• The Right-Hand Thumb Rule is used to determine the direction of the magnetic field around a current-carrying conductor.
• If a straight conductor is held in the right hand such that the Thumb points in the direction of current,
• The curled fingers show the direction of the Magnetic Field Lines around the conductor.
• This rule explains the circular pattern of magnetic field lines around a straight conductor.
• If the direction of current is reversed, the direction indicated by the curled fingers also reverses.
• The rule applies to straight conductors and helps in understanding magnetic field direction easily.
• It confirms the relationship between Electric Current and Magnetism.

12.2.3 Magnetic Field due to a Current through a Circular Loop

• When current flows through a Circular Loop, it produces a magnetic field around it.
• At every point on the loop, the magnetic field lines are concentric circles around the wire.
• At the centre of the loop, the magnetic field lines become nearly Straight and Parallel, indicating a stronger field.
• The direction of the magnetic field can be determined using the Right-Hand Thumb Rule.
• The strength of the magnetic field at the centre increases with increase in the Current.
• The magnetic field strength also increases with increase in the Number of Turns in the loop.
• A circular current-carrying loop behaves like a small Bar Magnet, having a north and south pole.

12.2.4 Magnetic Field due to a Current in a Solenoid

• A Solenoid is a long cylindrical coil consisting of many circular turns of insulated copper wire.
• When electric current flows through a solenoid, it produces a magnetic field similar to that of a Bar Magnet.
• The magnetic field lines inside the solenoid are Parallel and Closely Spaced, indicating a strong and uniform magnetic field.
• Outside the solenoid, the magnetic field is weak and resembles the field pattern of a bar magnet.
• One end of the solenoid behaves as a North Pole and the other end as a South Pole.
• The direction of magnetic field can be determined using the Right-Hand Thumb Rule.
• The strength of the magnetic field increases with increase in the Current and Number of Turns per Unit Length.

12.3 Force on a current-carrying conductor in a magnetic field

• When a Current-Carrying Conductor is placed in a magnetic field, it experiences a Force.
• The direction of the force depends on the direction of Current and the direction of the Magnetic Field.
• If the current direction is reversed, the direction of force also reverses.
• If the magnetic field direction is reversed, the force direction changes accordingly.
• The direction of force is given by Fleming’s Left-Hand Rule.
• According to this rule, if the thumb, forefinger and middle finger of the left hand are held mutually perpendicular,
• The Forefinger indicates magnetic field direction, the Middle Finger indicates current direction and the Thumb shows the direction of force (motion).
• This principle is used in the working of an Electric Motor.

12.4 Domestic electric circuits

• In domestic wiring, electrical appliances are connected in Parallel Combination to ensure the same potential difference across each device.
• The potential difference supplied to homes in India is approximately 220 V.
• Two types of wires are used: Live Wire (carries current) and Neutral Wire (completes the circuit).
• A third wire called the Earth Wire is used for safety to prevent electric shock.
• An Electric Fuse is connected in series with the live wire to protect the circuit from overload or short circuit.
• A Short Circuit occurs when live and neutral wires come into direct contact, causing excessive current flow.
• An Overloading condition occurs when too many appliances draw current from the same circuit.
• Proper insulation and earthing ensure safe use of electrical appliances in households.

Exam Oriented Facts

• A Magnetic Field is the region around a magnet where magnetic force is experienced.
• Magnetic field lines emerge from the North Pole and enter the South Pole outside the magnet.
• Inside the magnet, field lines move from South to North, forming closed loops.
• Field lines never intersect.
• Closer field lines indicate a Stronger Magnetic Field.
• A Current-Carrying Conductor produces a magnetic field around it.
• Magnetic field lines around a straight conductor are Concentric Circles.
• Field strength increases with increase in Current.
• Field strength decreases with increase in Distance from Conductor.
• Thumb → Direction of Current.
• Curled Fingers → Direction of Magnetic Field.
• Used to determine magnetic field around straight conductor and loop.
• Magnetic field at the centre of a circular loop becomes nearly Straight and Parallel.
• Strength increases with Current and Number of Turns.
• A Solenoid produces a magnetic field similar to a Bar Magnet.
• Inside a solenoid, magnetic field is Uniform and Strong.
• A conductor carrying current in a magnetic field experiences a Force.
• Direction given by Fleming’s Left-Hand Rule.
• Forefinger → Magnetic Field.
• Middle Finger → Current.
• Thumb → Force (Motion).
• Principle used in Electric Motor.
• Appliances connected in Parallel.
• Domestic supply voltage in India: 220 V.
• Wires: Live, Neutral, Earth.
• Fuse protects circuit from overload.
• Short Circuit → Direct contact of live and neutral wires.
• Overloading → Excess current drawn by multiple appliances.

NCERT Class 10 Science Chapter 12 – Magnetic Effects of Electric Current builds a strong conceptual link between electricity and magnetism. A clear understanding of NCERT Class 10 Science Chapter 12 helps students master right-hand thumb rule, Fleming’s left-hand rule and domestic wiring concepts.

NCERT Class 10 Science Chapter 12 is a scoring chapter in CBSE exams and forms the foundation for advanced electromagnetism topics.

Continue reading NCERT Class 10 Science Chapter 13 – Our Environment to understand environmental science concepts.

FAQs

Q1. What is NCERT Class 10 Science Chapter 12 about?
NCERT Class 10 Science Chapter 12 explains magnetic fields, magnetic effects of current and domestic electric circuits.

Q2. What is the Right-Hand Thumb Rule in NCERT Class 10 Science Chapter 12?
It is used to determine the direction of magnetic field around a current-carrying conductor.

Q3. What rule is used to find the direction of force in NCERT Class 10 Science Chapter 12?
Fleming’s Left-Hand Rule.

Q4. What is the domestic supply voltage in India according to NCERT Class 10 Science Chapter 12?
Approximately 220 V.

Q5. Why is NCERT Class 10 Science Chapter 12 important for exams?
Because questions based on magnetic field, Fleming’s rule and domestic circuits are frequently asked in CBSE exams.

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