Magnetic Effects of Electric Current : āĻŦ⧈āĻĻā§āϝ⧁āϤāĻŋāĻ• āϧāĻžā§°āĻžā§° āϚ⧁āĻŽā§āĻŦāϕ⧀āϝāĻŧ āĻĒā§ā§°āĻ­āĻžā§ą : PYQ









Magnetic Effects of Electric Current : āĻŦ⧈āĻĻā§āϝ⧁āϤāĻŋāĻ• āϧāĻžā§°āĻžā§° āϚ⧁āĻŽā§āĻŦāϕ⧀āϝāĻŧ āĻĒā§ā§°āĻ­āĻžā§ą


1 Mark PYQ (1 āύāĻŽā§āĻŦā§°)

Q1. What is the SI unit of magnetic field ? āĻĒā§ā§°āĻļā§āύ: āϚ⧁āĻŽā§āĻŦāϕ⧀āϝāĻŧ āĻ•ā§āώ⧇āĻ¤ā§ā§°ā§° SI āĻāĻ•āĻ• āĻ•āĻŋ ?


Ans: Tesla (T) āωāĻ¤ā§āϤ⧰: āĻŸā§‡āĻ›āϞāĻž (T)


Q2. Name the rule used to determine the direction of magnetic field around a current carrying conductor. āĻĒā§ā§°āĻļā§āύ: āĻŦāĻŋāĻĻā§āĻ¯ā§ā§Ž āϧāĻžā§°āĻž āĻŦāĻšāύ āϕ⧰āĻž āĻĒā§°āĻŋāĻŦāĻžāĻšāϕ⧰ āϚāĻžā§°āĻŋāĻ“āĻĢāĻžāϞ⧇ āϚ⧁āĻŽā§āĻŦāϕ⧀āϝāĻŧ āĻ•ā§āώ⧇āĻ¤ā§ā§°ā§° āĻĻāĻŋāĻļ āύāĻŋāĻ°ā§āĻŖāϝāĻŧ āϕ⧰āĻŋāĻŦāϞ⧈ āϕ⧋āύāĻŸā§‹ āύāĻŋāϝāĻŧāĻŽ āĻŦā§āĻ¯ā§ąāĻšāĻžā§° āϕ⧰āĻž āĻšāϝāĻŧ ?

Ans: Right Hand Thumb Rule (Maxwell’s Right Hand Thumb Rule)
āωāĻ¤ā§āϤ⧰: āϏ⧋āρ āĻšāĻžāϤ⧰ āĻŦ⧁āĻĸāĻŧāĻž āφāϙ⧁āϞāĻŋā§° āύāĻŋāϝāĻŧāĻŽ (āĻŽā§‡āĻ•ā§āĻ¸ā§ąā§‡āϞ⧰ Right Hand Thumb Rule)


Q3. What is the nature of magnetic field produced by a straight current carrying conductor ? āĻĒā§ā§°āĻļā§āύ: āϏ⧋āϜāĻž āĻŦāĻŋāĻĻā§āĻ¯ā§ā§Ž āϧāĻžā§°āĻž āĻŦāĻšāύ āϕ⧰āĻž āϤāĻžā§° āĻāĻĄāĻžāϞ⧰ āĻĻā§āĻŦāĻžā§°āĻž āϏ⧃āĻˇā§āϟāĻŋ āĻšā§‹ā§ąāĻž āϚ⧁āĻŽā§āĻŦāϕ⧀āϝāĻŧ āĻ•ā§āώ⧇āĻ¤ā§ā§°ā§° āĻĒā§ā§°āĻ•ā§ƒāϤāĻŋ āĻ•āĻŋ ?

Ans: Concentric circular magnetic field lines around the conductor.
āωāĻ¤ā§āϤ⧰: āĻĒā§°āĻŋāĻŦāĻžāĻšāϕ⧰ āϚāĻžā§°āĻŋāĻ“āĻĢāĻžāϞ⧇ āϏāĻŽāϕ⧇āĻ¨ā§āĻĻā§ā§°āĻŋāĻ• āĻŦ⧃āĻ¤ā§āϤāĻžāĻ•āĻžā§° āϚ⧁āĻŽā§āĻŦāϕ⧀āϝāĻŧ āĻ•ā§āώ⧇āĻ¤ā§ā§°ā§° ⧰⧇āĻ–āĻž āĻ—āĻ āύ āĻšāϝāĻŧāĨ¤


2 Marks PYQ (2 āύāĻŽā§āĻŦā§°)

Q4. State Fleming's Left Hand Rule. āĻĒā§ā§°āĻļā§āύ: āĻĢā§āϞ⧇āĻŽāĻŋāς⧰ āĻŦāĻžāρāĻ“ āĻšāĻžāϤ⧰ āύāĻŋāϝāĻŧāĻŽ āϞāĻŋāĻ–āĻžāĨ¤


Ans: Stretch the thumb, forefinger, and middle finger of your left hand so that they are mutually perpendicular.



  • Forefinger → Magnetic Field

  • Middle Finger → Current

  • Thumb → Force / Motion of Conductor


āωāĻ¤ā§āϤ⧰: āĻŦāĻžāρāĻ“ āĻšāĻžāϤ⧰ āĻŦ⧁āĻĸāĻŧāĻž āφāϙ⧁āϞāĻŋ, āĻ¤ā§°ā§āϜāύ⧀ āφ⧰⧁ āĻŽāĻžāϜ⧰ āφāϙ⧁āϞāĻŋāĻŸā§‹ āĻĒā§°āĻ¸ā§āĻĒā§°ā§° āϏ⧈āϤ⧇ ⧝ā§Ļ° āϕ⧋āĻŖāϤ ā§°āĻžāĻ–āĻžāĨ¤



  • āĻ¤ā§°ā§āϜāύ⧀ → āϚ⧁āĻŽā§āĻŦāϕ⧀āϝāĻŧ āĻ•ā§āώ⧇āĻ¤ā§ā§°

  • āĻŽāĻžāϜ⧰ āφāϙ⧁āϞāĻŋ → āϧāĻžā§°āĻž (Current)

  • āĻŦ⧁āĻĸāĻŧāĻž āφāϙ⧁āϞāĻŋ → āĻŦāϞ āĻŦāĻž āĻ—āϤāĻŋ


Easy Trick: F → Field, C → Current, T → Thrust
āϏāĻšāϜ āĻŸā§ā§°āĻŋāĻ•: F → Field, C → Current, T → Thrust


Q5. Write any two factors on which the strength of magnetic field around a straight conductor depends. āĻĒā§ā§°āĻļā§āύ: āϏ⧋āϜāĻž āĻĒā§°āĻŋāĻŦāĻžāĻšāϕ⧰ āϚāĻžā§°āĻŋāĻ“āĻĢāĻžāϞ⧇ āϚ⧁āĻŽā§āĻŦāϕ⧀āϝāĻŧ āĻ•ā§āώ⧇āĻ¤ā§ā§°ā§° āĻļāĻ•ā§āϤāĻŋ āϕ⧋āύ āĻĻ⧁āϟāĻž āĻ•āĻžā§°āϕ⧰ āĻ“āĻĒā§°āϤ āύāĻŋā§°ā§āĻ­ā§° āϕ⧰⧇?

Ans:



  1. Magnitude of current flowing through the conductor

  2. Distance from the conductor


āωāĻ¤ā§āϤ⧰:



  1. āĻĒā§°āĻŋāĻŦāĻžāĻšāϕ⧰ āĻŽāĻžāĻœā§‡ā§°ā§‡ āĻŦā§‹ā§ąāĻž āϧāĻžā§°āĻžā§° āĻĒā§°āĻŋāĻŽāĻžāĻŖ

  2. āĻĒā§°āĻŋāĻŦāĻžāĻšāϕ⧰ āĻĒā§°āĻž āĻĻā§‚ā§°āĻ¤ā§āĻŦ


More current = Stronger magnetic field
āĻ…āϧāĻŋāĻ• āϧāĻžā§°āĻž = āĻ…āϧāĻŋāĻ• āĻļāĻ•ā§āϤāĻŋāĻļāĻžāϞ⧀ āϚ⧁āĻŽā§āĻŦāϕ⧀āϝāĻŧ āĻ•ā§āώ⧇āĻ¤ā§ā§°


3 MARKS PYQ (3 āύāĻŽā§āĻŦā§°)

Q6. What is an electromagnet? Write two uses of an electromagnet. āĻĒā§ā§°āĻļā§āύ: āχāϞ⧇āĻ•ā§āĻŸā§ā§°ā§‹āĻŽā§‡āĻ—āύ⧇āϟ āĻ•āĻŋ? āχāϝāĻŧāĻžā§° āĻĻ⧁āϟāĻž āĻŦā§āĻ¯ā§ąāĻšāĻžā§° āϞāĻŋāĻ–āĻžāĨ¤


Ans: An electromagnet is a temporary magnet produced when electric current flows through a coil wound around a soft iron core.


Uses:



  1. Used in electric bells

  2. Used in cranes to lift heavy iron objects


āωāĻ¤ā§āϤ⧰: āχāϞ⧇āĻ•ā§āĻŸā§ā§°ā§‹āĻŽā§‡āĻ—āύ⧇āϟ āĻšā§ˆāϛ⧇ āĻāϟāĻž āĻ…āĻ¸ā§āĻĨāĻžāϝāĻŧā§€ āϚ⧁āĻŽā§āĻŦāĻ•, āϝāĻŋ āϕ⧋āĻŽāϞ āϞ⧋āĻšāĻžā§° āϕ⧋⧰⧰ āĻ“āĻĒā§°āϤ āϜāĻĄāĻŧā§‹ā§ąāĻž āĻ•āϝāĻŧ⧇āϞ⧰ āĻŽāĻžāĻœā§‡ā§°ā§‡ āĻŦāĻŋāĻĻā§āĻ¯ā§ā§Ž āϧāĻžā§°āĻž āĻŦā§‹ā§ąāĻžāϞ⧇ āϏ⧃āĻˇā§āϟāĻŋ āĻšāϝāĻŧāĨ¤


āĻŦā§āĻ¯ā§ąāĻšāĻžā§°:



  1. āχāϞ⧇āĻ•ā§āĻŸā§ā§°āĻŋāĻ• āĻŦ⧇āϞāϤ āĻŦā§āĻ¯ā§ąāĻšāĻžā§° āϕ⧰āĻž āĻšāϝāĻŧ

  2. āĻĄāĻžāϙ⧰ āϞ⧋āĻšāĻžā§° āĻŦāĻ¸ā§āϤ⧁ āϤ⧁āϞāĻŋāĻŦāϞ⧈ āĻ•ā§āϰ⧇āύāϤ āĻŦā§āĻ¯ā§ąāĻšāĻžā§° āϕ⧰āĻž āĻšāϝāĻŧ


Q7. Define electric motor. Write its principle. āĻĒā§ā§°āĻļā§āύ: āĻŦ⧈āĻĻā§āϝ⧁āϤāĻŋāĻ• āĻŽā§‹āϟ⧰ āϏāĻ‚āĻœā§āĻžāĻž āĻĻāĻŋāϝāĻŧāĻž āφ⧰⧁ āχāϝāĻŧāĻžā§° āύ⧀āϤāĻŋ āϞāĻŋāĻ–āĻžāĨ¤

Ans: An electric motor is a device that converts electrical energy into mechanical energy.


Principle: A current carrying conductor placed in a magnetic field experiences a force, which causes rotation of the conductor.


āωāĻ¤ā§āϤ⧰: āĻŦ⧈āĻĻā§āϝ⧁āϤāĻŋāĻ• āĻŽā§‹āϟ⧰ āĻšā§ˆāϛ⧇ āĻāύ⧇ āĻāϟāĻž āϝāĻ¨ā§āĻ¤ā§ā§° āϝāĻŋāϝāĻŧ⧇ āĻŦ⧈āĻĻā§āϝ⧁āϤāĻŋāĻ• āĻļāĻ•ā§āϤāĻŋāĻ• āϝāĻžāĻ¨ā§āĻ¤ā§ā§°āĻŋāĻ• āĻļāĻ•ā§āϤāĻŋāϞ⧈ ā§°ā§‚āĻĒāĻžāĻ¨ā§āϤ⧰ āϕ⧰⧇āĨ¤


āύ⧀āϤāĻŋ: āϚ⧁āĻŽā§āĻŦāϕ⧀āϝāĻŧ āĻ•ā§āώ⧇āĻ¤ā§ā§°āϤ ā§°āĻ–āĻž āϧāĻžā§°āĻž āĻŦāĻšāύ āϕ⧰āĻž āĻĒā§°āĻŋāĻŦāĻžāĻšāϕ⧇ āĻāϟāĻž āĻŦāϞ āĻ…āύ⧁āĻ­ā§ą āϕ⧰⧇, āϝāĻžā§° āĻĢāϞāϤ āĻĒā§°āĻŋāĻŦāĻžāĻšāĻ• āĻ˜ā§‚ā§°ā§‡āĨ¤


5 MARKS PYQ (5 āύāĻŽā§āĻŦā§°)














Ans: The Right Hand Thumb Rule states that if we hold a current carrying conductor in our right hand such that the thumb points in the direction of current, then the curled fingers show the direction of magnetic field lines.


Diagram Description:



  • Thumb → Direction of current

  • Curved fingers → Direction of magnetic field


āωāĻ¤ā§āϤ⧰: āϏ⧋āρ āĻšāĻžāϤ⧰ āĻŦ⧁āĻĸāĻŧāĻž āφāϙ⧁āϞāĻŋā§° āύāĻŋāϝāĻŧāĻŽ āĻ…āύ⧁āϏāĻžā§°ā§‡, āϝāĻĻāĻŋ āφāĻŽāĻŋ āĻŦāĻŋāĻĻā§āĻ¯ā§ā§Ž āϧāĻžā§°āĻž āĻŦāĻšāύ āϕ⧰āĻž āĻĒā§°āĻŋāĻŦāĻžāĻšāĻ•āĻŸā§‹ āϏ⧋āρ āĻšāĻžāϤ⧇ āϧ⧰āĻŋ āĻŦ⧁āĻĸāĻŧāĻž āφāϙ⧁āϞāĻŋāĻŸā§‹ āϧāĻžā§°āĻžā§° āĻĻāĻŋāĻļāϞ⧈ ā§°āĻžāĻ–ā§‹āρ, āϤ⧇āĻ¨ā§āϤ⧇ āĻŦāĻžāϕ⧀ āφāϙ⧁āϞāĻŋāϏāĻŽā§‚āĻšā§° āĻŦ⧇āρāĻ•āĻž āĻ…ā§ąāĻ¸ā§āĻĨāĻžāχ āϚ⧁āĻŽā§āĻŦāϕ⧀āϝāĻŧ āĻ•ā§āώ⧇āĻ¤ā§ā§°ā§° āĻĻāĻŋāĻļ āĻĻ⧇āĻ–ā§ā§ąāĻžāϝāĻŧāĨ¤


Q2. Describe the construction and working of an electric motor. āĻĒā§ā§°āĻļā§āύ: āĻŦ⧈āĻĻā§āϝ⧁āϤāĻŋāĻ• āĻŽā§‹āϟ⧰⧰ āĻ—āĻ āύ āφ⧰⧁ āĻ•āĻžā§°ā§āϝāĻĒā§ā§°āĻŖāĻžāϞ⧀ āĻŦā§°ā§āĻŖāύāĻž āϕ⧰āĻžāĨ¤

Construction:



  1. Rectangular coil

  2. Permanent magnet

  3. Split ring (commutator)

  4. Brushes

  5. Battery


Working: When current flows through the coil placed in a magnetic field, opposite forces act on the two sides of the coil (Fleming’s Left Hand Rule). This produces rotation and converts electrical energy into mechanical energy.


āĻ—āĻ āύ:



  1. āφāϝāĻŧāϤāĻžāĻ•āĻžā§° āĻ•āϝāĻŧ⧇āϞ

  2. āĻ¸ā§āĻĨāĻžāϝāĻŧā§€ āϚ⧁āĻŽā§āĻŦāĻ•

  3. āĻ¸ā§āĻĒā§āϞāĻŋāϟ ā§°āĻŋāĻ‚ (āĻ•āĻŽāĻŋāωāĻŸā§‡āϟ⧰)

  4. āĻŦā§ā§°āĻžāĻļ

  5. āĻŦā§āϝāĻžāϟāĻžā§°ā§€


āĻ•āĻžā§°ā§āϝāĻĒā§ā§°āĻŖāĻžāϞ⧀: āϚ⧁āĻŽā§āĻŦāϕ⧀āϝāĻŧ āĻ•ā§āώ⧇āĻ¤ā§ā§°āϤ āĻĨāĻ•āĻž āĻ•āϝāĻŧ⧇āϞ⧰ āĻŽāĻžāĻœā§‡ā§°ā§‡ āϧāĻžā§°āĻž āĻŦā§‹ā§ąāĻžāϞ⧇ āĻ•āϝāĻŧ⧇āϞ⧰ āĻĻ⧁āϝāĻŧā§‹ āĻĢāĻžāϞ⧇ āĻŦāĻŋāĻĒā§°ā§€āϤ āĻŦāϞ āϞāĻžāϗ⧇āĨ¤ āĻĢāϞāϤ āĻ•āϝāĻŧ⧇āϞ āĻ˜ā§‚ā§°ā§‡ āφ⧰⧁ āĻŦ⧈āĻĻā§āϝ⧁āϤāĻŋāĻ• āĻļāĻ•ā§āϤāĻŋ āϝāĻžāĻ¨ā§āĻ¤ā§ā§°āĻŋāĻ• āĻļāĻ•ā§āϤāĻŋāϤ āĻĒā§°āĻŋāĻŖāϤ āĻšāϝāĻŧāĨ¤


MCQs


Q1. Explain the Right Hand Thumb Rule with a diagram description. āĻĒā§ā§°āĻļā§āύ: āϏ⧋āρ āĻšāĻžāϤ⧰ āĻŦ⧁āĻĸāĻŧāĻž āφāϙ⧁āϞāĻŋā§° āύāĻŋāϝāĻŧāĻŽ āĻŦā§āϝāĻžāĻ–ā§āϝāĻž āϕ⧰āĻžāĨ¤


Q1. The SI unit of magnetic field is -Tesla / Watt / Volt / Ohm


Ans: Tesla


Q2. Which rule gives the direction of force on a current carrying conductor?Right Hand Thumb Rule | Fleming’s Left Hand Rule | Ohm’s Law | Faraday’s Law


Ans: Fleming’s Left Hand Rule


Q3. Magnetic field lines around a straight conductor are - Straight lines / Circular / Random / Zigzag


Ans: Circular


Q4. An electric motor converts -


Mechanical → Electrical / Electrical → Mechanical / Heat → Electrical / Light → Mechanical


Ans: Electrical → Mechanical


Q5. The core used in an electromagnet is made of - Steel / Copper / Soft Iron / Aluminium


Ans: Soft Iron


 Most Important Exam Notes : āĻ…āϤāĻŋ āϗ⧁⧰⧁āĻ¤ā§āĻŦāĻĒā§‚ā§°ā§āĻŖ āĻĒā§°ā§€āĻ•ā§āώāĻžā§° āύ⧋āϟ


1. More current → Stronger magnetic field : āĻ…āϧāĻŋāĻ• āϧāĻžā§°āĻž → āĻ…āϧāĻŋāĻ• āĻļāĻ•ā§āϤāĻŋāĻļāĻžāϞ⧀ āϚ⧁āĻŽā§āĻŦāϕ⧀āϝāĻŧ āĻ•ā§āώ⧇āĻ¤ā§ā§°


2. Magnetic field decreases with distance : āĻĻā§‚ā§°āĻ¤ā§āĻŦ āĻŦāĻžāĻĸāĻŧāĻŋāϞ⧇ āϚ⧁āĻŽā§āĻŦāϕ⧀āϝāĻŧ āĻ•ā§āώ⧇āĻ¤ā§ā§° āĻ•āĻŽā§‡


3. Electromagnets are temporary magnets : āχāϞ⧇āĻ•ā§āĻŸā§ā§°ā§‹āĻŽā§‡āĻ—āύ⧇āϟ āĻ…āĻ¸ā§āĻĨāĻžāϝāĻŧā§€ āϚ⧁āĻŽā§āĻŦāĻ•


4. Electric motor works on Fleming’s Left Hand Rule : āĻŦ⧈āĻĻā§āϝ⧁āϤāĻŋāĻ• āĻŽā§‹āϟ⧰ āĻĢā§āϞ⧇āĻŽāĻŋāς⧰ āĻŦāĻžāρāĻ“ āĻšāĻžāϤ⧰ āύāĻŋāϝāĻŧāĻŽāϤ āĻ•āĻžāĻŽ āϕ⧰⧇


5. Field lines never intersect : āϚ⧁āĻŽā§āĻŦāϕ⧀āϝāĻŧ āĻ•ā§āώ⧇āĻ¤ā§ā§°ā§° ⧰⧇āĻ–āĻžāĻŦā§‹ā§° āϕ⧇āϤāĻŋāϝāĻŧāĻžāĻ“ āĻāϜāύ⧇ āφāύāϜāύāĻ• āϛ⧇āĻĻ āύāϕ⧰⧇