Physics X - Chapter 13: Magnetic Effects of Electric Current
Master Magnetic Effects of Electric Current MCQs for Class 10. Learn electromagnets, electric motors, generators, and electromagnetic induction for science.
Quick Revision : Magnetic effect of electric current
- Oersted's Experiment: A current-carrying conductor produces a magnetic field around it, deflecting a nearby compass needle.
- Magnetic Field Lines: Imaginary lines representing magnetic field direction; emerge from the North pole and merge at the South pole. They never intersect.
- Right-Hand Thumb Rule: Grasp the conductor with your right hand; thumb points in the current direction, curled fingers show the direction of magnetic field lines.
- Magnetic Field due to a Solenoid: A current-carrying solenoid behaves like a bar magnet; the field inside is strong and uniform.
- Electromagnet: A strong magnet formed by placing a soft iron core inside a current-carrying solenoid.
- Fleming's Left-Hand Rule: Stretch thumb, forefinger, and middle finger mutually perpendicular. Forefinger = Magnetic Field, Middle finger = Current, Thumb = Force on conductor.
- Electric Motor: Converts electrical energy to mechanical energy. Uses a rotating coil in a magnetic field, with a split-ring commutator to reverse current direction.
- Electromagnetic Induction: Production of induced current in a coil due to relative motion between the coil and a magnet (or change in magnetic field).
- Fleming's Right-Hand Rule: Thumb = Motion of conductor, Forefinger = Magnetic Field, Middle finger = Induced Current direction.
- Electric Generator: Converts mechanical energy to electrical energy. AC generator has slip rings; DC generator uses a split-ring commutator.
- Domestic Electric Circuits: Uses live (red), neutral (black), and earth (green) wires. Fuses prevent damage from overloading or short circuits.
Basic Level Questions
Chapter Summary: Magnetic effect of electric current
This chapter explores the deep connection between electricity and magnetism. It begins with how an electric current creates a magnetic field (Oersted's discovery) and how to determine its direction using the Right-Hand Thumb Rule. You'll learn about the magnetic fields produced by different conductors like straight wires, circular loops, and solenoids. The chapter then explains the force on a current-carrying conductor in a magnetic field (Fleming's Left-Hand Rule) and its application in devices like the electric motor. The reverse phenomenon—how a moving magnet can generate electricity (electromagnetic induction)—is covered next, along with Fleming's Right-Hand Rule and the working of AC/DC generators. Finally, it details the safety aspects of domestic electric circuits.
You will learn the fundamental principles of electromagnetism, including how to visualise magnetic fields, predict the force on conductors, and understand the working principles of key technological devices like electric motors and generators. The chapter bridges abstract concepts (like field lines and induction) with practical applications (like circuit safety and appliance operation), giving you a complete picture of how magnetic effects power our modern world.
This chapter is a high-scoring and frequently tested unit in board exams and competitive tests like NTSE and Science Olympiads. It combines diagram-based questions (field lines, motor/generator diagrams), rule-based applications (Fleming's rules, Right-Hand Thumb rule), and theoretical explanations (motor vs. generator, AC vs. DC). Numerical problems on force and conceptual questions on electromagnetic induction are common. Mastering this chapter ensures you can tackle a variety of question formats confidently.