Class 10 Science Chapter 12 Magnetic Effects of Electric Current
March 22, 2025
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I. Chapter Summary
This chapter explores how electricity and magnetism are interrelated. It explains the discovery of magnetic effects due to electric current (Oersted’s experiment), and introduces the right-hand thumb rule, electromagnets, and electric motors. The chapter also explains the working of electric generators, electromagnetic induction (Faraday’s experiments), Fleming’s left-hand and right-hand rules, and the distinction between AC and DC current. It concludes with real-world applications in electric circuits and household devices.
II. Key Concepts Covered
Concept
Description
Magnetic Field
Region around a magnet or current-carrying wire where its magnetic influence is felt. Represented by magnetic field lines.
Oersted’s Experiment
Demonstrated that current through a conductor produces a magnetic field.
Right-Hand Thumb Rule
Determines direction of magnetic field around a current-carrying conductor.
Magnetic Field due to Current in a Solenoid
Solenoid behaves like a bar magnet; used in making electromagnets.
Electromagnet
A temporary magnet made by passing current through a solenoid.
Force on a Current-Carrying Conductor
The magnetic field exerts a force on a current-carrying conductor placed in it.
Fleming’s Left-Hand Rule
Used to find direction of force on a conductor (used in motors).
Electric Motor
Converts electrical energy into mechanical energy using magnetic force.
Electromagnetic Induction
The phenomenon of generating current by changing magnetic field.
Fleming’s Right-Hand Rule
Determines the direction of induced current (used in generators).
Electric Generator
Converts mechanical energy into electrical energy.
AC vs DC Current
– AC (Alternating Current): Changes direction periodically (used in homes).
– DC (Direct Current): Flows in one direction (used in batteries).
What is the direction of the magnetic field inside a current-carrying solenoid? a) Circular b) Along the axis ✅ (PYQ 2021) c) Perpendicular d) Opposite to current
Fleming’s Left-Hand Rule is used to find the direction of: a) Magnetic field b) Electric current c) Force ✅ (PYQ 2020) d) Motion of charge
Which of the following produces a magnetic field? a) A stationary charge b) A moving charge ✅ c) An insulator d) A glass rod
Which device converts mechanical energy to electrical energy? a) Electric Motor b) Electric Generator ✅ (PYQ 2019) c) Electromagnet d) Solenoid
(B) Short Answer Questions (2/3 Marks)
State the Right-Hand Thumb Rule and draw a neat diagram to explain it.
What is electromagnetic induction? Name one device based on this principle.
Differentiate between AC and DC. Which type is used in homes and why?
What is the function of a fuse in a circuit? Where is it placed in the domestic circuit and why?
(C) Long Answer Questions (5 Marks)
Explain the working of an electric motor with a labeled diagram. Mention its principle and applications.(PYQ 2019)
Describe the construction and working of an electric generator with a labeled diagram. Mention the type of current it produces.
What is the magnetic field due to a solenoid? Explain how an electromagnet is formed and list two uses.
Describe an activity to show that a magnetic field is produced around a current-carrying conductor. Explain the role of field lines in this context.
(D) HOTS (Higher Order Thinking Skills)
Why do power transmission lines carry AC instead of DC, even though both can transfer energy?
Why are electromagnets preferred over permanent magnets in electric bells and motors?
IV. Key Formulas/Concepts
Concept
Formula/Explanation
Magnetic Field Lines
Represent the direction of magnetic influence; tangent at any point shows direction of field.
Right-Hand Thumb Rule
Thumb → current; curled fingers → magnetic field lines.
Fleming’s Left-Hand Rule
Thumb → Force
Forefinger → Magnetic field
Middle finger → Current
Fleming’s Right-Hand Rule
Thumb → Motion of conductor
Forefinger → Magnetic field
Middle finger → Induced current
Electromagnetic Induction
Current induced in a conductor when placed in a changing magnetic field.
V. Deleted Portions (CBSE 2025–2026)
No portions have been deleted from this chapter as per the rationalized NCERT textbooks.
VI. Chapter-Wise Marks Bifurcation (Estimated – CBSE 2025–2026)
Unit/Chapter
Estimated Marks
Type of Questions Typically Asked
Chapter 12: Magnetic Effects of Electric Current
10–12 Marks
1 Long Answer, 2 Short Answers, 1–2 MCQs, Diagram
VII. Previous Year Questions (PYQs)
Year
Marks
Question
2021
1
Direction of magnetic field inside solenoid? (Along axis)
2020
1
Fleming’s Left-Hand Rule is used for? (Force direction)
2019
5
Working and diagram of an electric motor
2018
3
State and explain Right-Hand Thumb Rule
VIII. Real-World Application Examples to Connect with Topics
Application
Description
Electric Motor
Used in fans, mixers, washing machines, electric cars
Electric Generator
Found in power stations, dynamos, wind turbines
Electromagnets
Used in MRI machines, cranes to lift scrap metal, relays
AC vs DC
DC in batteries; AC in power grids and home appliances
MCBs and Fuses
Protect appliances from overload and short circuits
IX. Student Tips & Strategies for Success
Time Management
Practice diagrams of motor, generator, and field lines weekly.
Allocate 20 minutes daily for conceptual theory and 10 minutes for rules.
Exam Preparation
Use flashcards for Fleming’s rules, Right-Hand Thumb Rule, and key terms.
Practice drawing labeled diagrams and writing short explanations.
Stress Management
Use mnemonics like “FBI” for Fleming’s Left-Hand Rule (Force, B-field, Current).
Relate concepts to devices at home (fan, speaker, transformer).
