Chapter - 13 

Magnetic Effects of Electric Current

( āĻŦৈāĻĻ্āϝুāϤিāĻ• āĻĒ্ā§°āĻŦাāĻšā§° āϚুāĻŽ্āĻŦāĻ•ীāϝ় āĻĒ্ā§°āĻ­াā§ą )


EXERCISES :-

( āĻŦ্āϝাāϝ়াāĻŽ :- )

1. Which of the following correctly describes the magnetic field near a long straight wire?

( āύিāĻŽ্āύāϞিāĻ–িāϤ āĻ•োāύāϟোā§ąে āĻĻীāϘāϞ āĻĒোāύ āϤাঁā§°ā§° āĻ“āϚ⧰āϤ āϚুāĻŽ্āĻŦāĻ•ীāϝ় āĻ•্āώেāϤ্ā§°āϟো āϏāĻ িāĻ•āĻ­াā§ąে āĻŦā§°্āĻŖāύা āϕ⧰ে? )

(a) The field consists of straight lines perpendicular to the wire.

( āĻ•্āώেāϤ্ā§°āĻ–āύāϤ āϤাঁā§°ā§° āϞāĻŽ্āĻŦāĻ­াā§ąে āϏ⧰āϞ ā§°েāĻ–া āĻĨাāĻ•ে। )

(b) The field consists of straight lines parallel to the wire.

( āĻ•্āώেāϤ্ā§°āĻ–āύāϤ āϤাঁā§°ā§° āϏāĻŽাāύ্āϤ⧰াāϞāĻ­াā§ąে āϏ⧰āϞ ā§°েāĻ–া āĻĨাāĻ•ে। )

(c) The field consists of radial lines originating from the wire.

( āĻ•্āώেāϤ্ā§°āĻ–āύāϤ āϤাঁā§°ā§° āĻĒā§°া āωāĻĻ্āĻ­ā§ą āĻšোā§ąা ā§°েāĻĄিāϝ়েāϞ ā§°েāĻ–া āĻĨাāĻ•ে। )

(d) The field consists of concentric circles centred on the wire.

( āĻ•্āώেāϤ্ā§°āĻ–āύāϤ āϤাঁā§°ā§° āĻ“āĻĒā§°āϤ āĻ•েāύ্āĻĻ্ā§°ীāĻ­ূāϤ āϏāĻŽāĻ•েāύ্āĻĻ্ā§°িāĻ• āĻŦৃāϤ্āϤ āĻĨাāĻ•ে। )

Answer:-

2. The phenomenon of electromagnetic induction is

( āĻŦিāĻĻ্āϝুāϤāϚুāĻŽ্āĻŦāĻ•ীāϝ় āĻ…āύ্āϤ⧰্āĻ­ুāĻ•্āϤিā§° āĻĒā§°িāϘāϟāύা āĻšৈāĻ›ে )

(a) the process of charging a body.

( āĻļā§°ীā§° āĻāϟা āϚাā§°্āϜ āϕ⧰াā§° āĻĒ্ā§°āĻ•্ā§°িāϝ়া। )

(b) the process of generating magnetic field due to a current passing through a coil.

( āĻ•ুāĻŖ্āĻĄāϞীāĻāϟাā§° āĻŽাāϜেā§°ে āĻĒাā§° āĻšৈ āϝোā§ąা āĻŦিāĻĻ্āϝুāϤ⧰ āĻĢāϞāϤ āϚুāĻŽ্āĻŦāĻ•ীāϝ় āĻ•্āώেāϤ্ā§° āϏৃāώ্āϟি āϕ⧰াā§° āĻĒ্ā§°āĻ•্ā§°িāϝ়া। )

(c) producing induced current in a coil due to relative motion between a magnet and the coil.

( āϚুāĻŽ্āĻŦāĻ• āφ⧰ু āĻ•ুāĻŖ্āĻĄāϞীā§° āĻŽাāϜāϤ āφāĻĒেāĻ•্āώিāĻ• āĻ—āϤিā§° āĻŦাāĻŦে āĻ•ুāĻŖ্āĻĄāϞীāĻāϟাāϤ āĻĒ্ā§°েā§°িāϤ āĻŦিāĻĻ্āϝুā§Ž āĻĒ্ā§°āϏ্āϤুāϤ āϕ⧰া। )

(d) the process of rotating a coil of an electric motor.

( āĻŦৈāĻĻ্āϝুāϤিāĻ• āĻŽāϟ⧰⧰ āĻ•ুāĻŖ্āĻĄāϞী āϘূā§°াā§° āĻĒ্ā§°āĻ•্ā§°িāϝ়া। )

Answer:-

3. The device used for producing electric current is called a

( āĻŦৈāĻĻ্āϝুāϤিāĻ• āĻĒ্ā§°āĻŦাāĻš āĻĒ্ā§°āϏ্āϤুāϤ āϕ⧰াā§° āĻŦাāĻŦে āĻŦ্āĻ¯ā§ąāĻšৃāϤ āĻĄিāĻ­াāχāϚāϟোāĻ• āĻ• āĻŦুāϞি āĻ•োā§ąা āĻšāϝ় )

(a) generator.

( āϜেāύেā§°েāϟ⧰। )

(b) galvanometer.

( āĻ—াāϞāĻ­াāύোāĻŽিāϟাā§°। )

(c)ammeter.

( āĻāĻŽāĻŽিāϟাā§°। )

(d) motor.

( āĻŽāϟ⧰। )

Answer:-

4. The essential difference between an AC generator and a DC generator is that

(āĻāϚি āϜেāύেā§°েāϟ⧰ āφ⧰ু āĻĄিāϚি āϜেāύেā§°েāϟ⧰⧰ āĻŽাāϜ⧰ āĻ…āϤ্āϝাā§ąāĻļ্āϝāĻ•ীāϝ় āĻĒাā§°্āĻĨāĻ•্āϝ āĻšৈāĻ›ে āϝে)

(a) AC generator has an electromagnet while a DC generator has permanent magnet.

( āĻāϚি āϜেāύেā§°েāϟ⧰āϤ āχāϞেāĻ•্āϟ্ā§°āĻŽেāĻ—āύেāϟ āĻĨাāĻ•ে āφāύāĻšাāϤে āĻĄিāϚি āϜেāύেā§°েāϟ⧰⧰ āϏ্āĻĨাāϝ়ী āϚুāĻŽ্āĻŦāĻ• āĻĨাāĻ•ে। )

(b) DC generator will generate a higher voltage.

( āĻĄিāϚি āϜেāύেā§°েāϟ⧰ে āωāϚ্āϚāϤ⧰ āĻ­āϞ্āϟেāϜ āϏৃāώ্āϟি āϕ⧰িāĻŦ। )

(c) AC generator will generate a higher voltage.

( āĻāϚি āϜেāύেā§°েāϟ⧰ে āωāϚ্āϚāϤ⧰ āĻ­āϞ্āϟেāϜ āϏৃāώ্āϟি āϕ⧰িāĻŦ। )

(d) AC generator has slip rings while the DC generator has a commutator.

( āĻāϚি āϜেāύেā§°েāϟ⧰āϤ āϏ্āϞিāĻĒ ā§°িং āφāĻ›ে āφāύāĻšাāϤে āĻĄিāϚি āϜেāύেā§°েāϟ⧰āϤ āĻāϟা āĻ•āĻŽিāωāϟেāϟ⧰ āφāĻ›ে। )

Answer:-

5. At the time of short circuit, the current in the circuit

 āĻļ্āĻŦā§°্āϟ āϚাā§°্āĻ•িāϟ⧰ āϏāĻŽāϝ়āϤ, āĻŦā§°্āϤāύীāϤ āĻŦিāĻĻ্āϝুāϤ )

(a) reduces substantially.

( āϝāĻĨেāώ্āϟ āĻĒā§°িāĻŽাāĻŖে āĻš্ā§°াāϏ āĻšāϝ়। )

(b) does not change.

( āϏāϞāύি āύāĻšāϝ়। )

(c) increases heavily.

( āϝāĻĨেāώ্āϟ āĻŦৃāĻĻ্āϧি āĻšāϝ়। )

(d) vary continuously.

( āύিā§°āύ্āϤ⧰ āĻ­াā§ąে āĻĒৃāĻĨāĻ• āĻšāϝ়। )

Answer:-

6. State whether the following statements are true or false. 

( āύিāĻŽ্āύāϞিāĻ–িāϤ āĻŽāύ্āϤāĻŦ্āϝāĻŦোā§° āϏঁāϚা āύে āĻŽিāĻ›া āϏেāϝ়া āĻ•āĻ“ঁāĻ•।  )

(a) An electric motor converts mechanical energy into electrical energy.

( āĻāϟা āĻŦৈāĻĻ্āϝুāϤিāĻ• āĻŽāϟ⧰ে āϝাāύ্āϤ্ā§°িāĻ• āĻļāĻ•্āϤিāĻ• āĻŦৈāĻĻ্āϝুāϤিāĻ• āĻļāĻ•্āϤিāϞৈ ā§°ূāĻĒাāύ্āϤ⧰ āϕ⧰ে। )

(b) An electric generator works on the principle of electromagnetic induction.

( āĻŦৈāĻĻ্āϝুāϤিāĻ• āϜেāύেā§°েāϟ⧰ে āĻŦিāĻĻ্āϝুāϤāϚুāĻŽ্āĻŦāĻ•ীāϝ় āĻ…āύ্āϤ⧰্āĻ­ুāĻ•্āϤিā§° āϏিāĻĻ্āϧাāύ্āϤāϤ āĻ•াāĻŽ āϕ⧰ে। )

(c) The field at the centre of a long circular coil carrying current will be parallel straight lines.

(āĻŦিāĻĻ্āϝুā§Ž āĻ•āĻĸ়িāĻ“ā§ąা āĻĻীāϘāϞ āĻŦৃāϤ্āϤাāĻ•াā§° āĻ•ুāĻŖ্āĻĄāϞীā§° āĻ•েāύ্āĻĻ্ā§°āϤ āĻĨāĻ•া āĻĒāĻĨাā§°āĻ–āύ āϏāĻŽাāύ্āϤ⧰াāϞ āϏ⧰āϞ ā§°েāĻ–া āĻš'āĻŦ। )

(d) A wire with a green insulation is usually the live wire of an electric supply. 

( āϏেāωāϜীāϝ়া āχāύāϚুāϞেāϚāύ āĻĨāĻ•া āϤাঁā§° āĻšৈāĻ›ে āϏাāϧাā§°āĻŖāϤে āĻŦৈāĻĻ্āϝুāϤিāĻ• āϝোāĻ—াāύ⧰ āϜীā§ąāύ্āϤ āϤাঁā§°। )

Answer:-

7. List two methods of producing magnetic fields.

( āϚুāĻŽ্āĻŦāĻ•ীāϝ় āĻ•্āώেāϤ্ā§° āĻĒ্ā§°āϏ্āϤুāϤ āϕ⧰াā§° āĻĻুāϟা āĻĒāĻĻ্āϧāϤি āϤাāϞিāĻ•াāĻ­ুāĻ•্āϤ āϕ⧰āĻ•। )

Answer:-

8. How does a solenoid behave like a magnet? Can you determine the north and south poles of a current-carrying solenoid with the help of a bar magnet? Explain.

( āϚোāϞেāύāχāĻĄে āϚুāĻŽ্āĻŦāϕ⧰ āĻĻā§°ে āĻ•েāύে āφāϚ⧰āĻŖ āϕ⧰ে? āφāĻĒুāύি āĻŦাā§° āϚুāĻŽ্āĻŦāϕ⧰ āϏāĻšাāϝ়āϤ āĻŦিāĻĻ্āϝুā§Ž āĻ•āĻĸ়িāĻ“ā§ąা āϚোāϞেāύāχāĻĄā§° āωāϤ্āϤ⧰ āφ⧰ু āĻĻāĻ•্āώিāĻŖ āĻŽেā§°ু āύিā§°্āϧাā§°āĻŖ āϕ⧰িāĻŦ āĻĒাā§°িāĻŦāύে? āĻŦ্āϝাāĻ–্āϝা āϕ⧰āĻ•। )

Answer:-

9. When is the force experienced by a current-carrying conductor placed in a magnetic field largest?

( āϚুāĻŽ্āĻŦāĻ•ীāϝ় āĻ•্āώেāϤ্ā§°āϤ āϏ⧰্āĻŦāĻŦৃāĻšā§Ž āϏ্āĻĨাāύāϤ ā§°āĻ–া āĻŦā§°্āϤāĻŽাāύ āĻ•āĻĸ়িāĻ“ā§ąা āĻĒā§°িāĻŦাāĻšীā§° āĻĻ্āĻŦাā§°া āĻ•েāϤিāϝ়া āĻŦāϞ āĻ…āύুāĻ­ā§ą āϕ⧰া āĻšāϝ়? )

Answer:-

10. Imagine that you are sitting in a chamber with your back to one wall. An electron beam, moving horizontally from back wall towards the front wall, is deflected by a strong magnetic field to your right side. What is the direction of magnetic field?

( āĻ•āϞ্āĻĒāύা āϕ⧰āĻ• āϝে āφāĻĒুāύি āĻāĻ–āύ āĻŦেā§°āϤ āĻĒিāĻ ি āĻĻি āĻāϟা āϚেāĻŽ্āĻŦাā§°āϤ āĻŦāĻšি āφāĻ›ে। āĻĒিāĻ›āĻĢাāϞ⧰ āĻŦেā§°ā§° āĻĒā§°া āϏāύ্āĻŽুāĻ–ā§° āĻŦেā§°ā§° āĻĢাāϞে āĻĒāĻĨাāϞিāĻ•ৈ āϚāϞাāϚāϞ āϕ⧰া āχāϞেāĻ•্āϟ্ā§°āύ āĻŦীāĻŽ āĻāϟা āĻļāĻ•্āϤিāĻļাāϞী āϚুāĻŽ্āĻŦāĻ•ীāϝ় āĻ•্āώেāϤ্ā§°ā§° āĻĻ্āĻŦাā§°া āφāĻĒোāύাā§° āϏোঁāĻĢাāϞে āĻŦিāϚ্āϝুāϤ āĻšāϝ়। āϚুāĻŽ্āĻŦāĻ•ীāϝ় āĻ•্āώেāϤ্ā§°ā§° āĻĻিāĻļ āĻ•ি? )

Answer:-

11. Draw a labelled diagram of an electric motor. Explain its principle and working. What is the function of a split ring in an electric motor?

( āĻŦৈāĻĻ্āϝুāϤিāĻ• āĻŽāϟ⧰⧰ āϞেāĻŦেāϞ āϝুāĻ•্āϤ āύāĻ•্āϏা āφঁāĻ•āĻ•। āχāϝ়াā§° āύীāϤি āφ⧰ু āĻ•াāĻŽ āĻŦ্āϝাāĻ–্āϝা āϕ⧰āĻ•। āĻŦৈāĻĻ্āϝুāϤিāĻ• āĻŽāϟ⧰āϤ āϏ্āĻĒ্āϞিāϟ ā§°িং āĻāϟাā§° āĻ•াāĻŽ āĻ•ি? )

Answer:-

12. Name some devices in which electric motors are used.

( āĻŦৈāĻĻ্āϝুāϤিāĻ• āĻŽāϟ⧰ āĻŦ্āĻ¯ā§ąāĻšাā§° āϕ⧰া āĻ•িāĻ›ুāĻŽাāύ āĻĄিāĻ­াāχāϚ⧰ āύাāĻŽ āĻĻিāϝ়āĻ•। )

Answer:-

13. A coil of insulated copper wire is connected to a galvanometer. What will happen if a bar magnet is (i) pushed into the coil, (ii) withdrawn from inside the coil, (iii) held stationary inside the coil?

( āχāύāϚুāϞেāϟেāĻĄ āϤাāĻŽā§° āϤাঁā§°ā§° āĻ•ুāĻŖ্āĻĄāϞী āĻāϟা āĻ—াāϞāĻ­াāύোāĻŽিāϟাā§°ā§° āϏৈāϤে āϏংāϝোāϜিāϤ āĻšāϝ়। āϝāĻĻি āĻŦাā§° āϚুāĻŽ্āĻŦāĻ• āĻāϟা āĻ•ুāĻŖ্āĻĄāϞীāϤ āĻ েāϞি āĻĻিāϝ়া āĻšāϝ়, (āφāχāφāχ) āĻ•ুāĻŖ্āĻĄāϞীā§° āĻ­িāϤ⧰⧰ āĻĒā§°া āĻĒ্ā§°āϤ্āϝাāĻšাā§° āϕ⧰া āĻšāϝ়, (āϤৃāϤীāϝ়) āĻ•ুāĻŖ্āĻĄāϞীā§° āĻ­িāϤ⧰āϤ āϏ্āĻĨিā§° āĻšৈ āĻĨাāĻ•ে āϤেāύেāĻš'āϞে āĻ•ি āĻš'āĻŦ? )

Answer;-

14. Two circular coils A and B are placed closed to each other. If the current in the coil A is changed, will some current be induced in the coil B? Give reason.

( āĻĻুāϟা āĻŦৃāϤ্āϤাāĻ•াā§° āĻ•ুāĻŖ্āĻĄāϞী āĻ āφ⧰ু āĻŦি āχāϜāύে āϏিāϜāύ⧰ āĻŦাāĻŦে āĻŦāύ্āϧ āϕ⧰া āĻšāϝ়। āϝāĻĻি āĻ•ুāĻŖ্āĻĄāϞী āĻ-āϤ āĻĨāĻ•া āĻŦিāĻĻ্āϝুāϤ āĻĒā§°িā§ąā§°্āϤāύ āϕ⧰া āĻšāϝ়, āĻ•ুāĻŖ্āĻĄāϞী āĻŦি-āϤ āĻ•িāĻ›ু āĻŦিāĻĻ্āϝুā§Ž āĻĒ্ā§°েā§°িāϤ āĻš'āĻŦ āύেāĻ•ি? āĻ•াā§°āĻŖ āĻĻিāϝ়āĻ•। )

Answer:-

15. State the rule to determine the direction of a (i) magnetic field produced around a straight conductor-carrying current, (ii) force experienced by a current-carrying straight conductor placed in a magnetic field which is perpendicular to it, and (iii) current induced in a coil due to its rotation in a magnetic field.

( āĻāϟা āĻĒোāύ āĻĒā§°িāĻŦাāĻšী āĻ•āĻĸ়িāĻ“ā§ąা āĻĒ্ā§°āĻŦাāĻšā§° āϚাā§°িāĻ“āĻĢাāϞে āĻ‰ā§ŽāĻĒāύ্āύ āĻšোā§ąা (āĻ•) āϚুāĻŽ্āĻŦāĻ•ীāϝ় āĻ•্āώেāϤ্ā§°ā§° āĻĻিāĻļ āύিā§°্āϧাā§°āĻŖ āϕ⧰াā§° āύিāϝ়āĻŽ āϟো āĻ•āĻ“ঁāĻ•, (āĻ–) āϚুāĻŽ্āĻŦāĻ•ীāϝ় āĻ•্āώেāϤ্ā§°āϤ ā§°āĻ–া āĻāĻ• āĻŦā§°্āϤāĻŽাāύ-āĻ•āĻĸ়িāĻ“ā§ąা āĻĒোāύ āĻĒā§°িāĻŦাāĻšীā§° āĻĻ্āĻŦাā§°া āĻ…āύুāĻ­ā§ą āϕ⧰া, āϝি āχāϝ়াā§° āϞāĻŽ্āĻŦ, āφ⧰ু (āĻ—) āϚুāĻŽ্āĻŦāĻ•ীāϝ় āĻ•্āώেāϤ্ā§°āϤ āχāϝ়াā§° āϘূā§°্āĻŖāύ⧰ āĻĢāϞāϤ āĻ•ুāĻŖ্āĻĄāϞীāĻāϟাāϤ āĻĒ্ā§°েā§°িāϤ āĻšোā§ąা āĻŦিāĻĻ্āϝুāϤ। )

Answer:-

16. Explain the underlying principle and working of an electric generator by drawing a labelled diagram. What is the function of brushes?

( āϞেāĻŦেāϞ āϝুāĻ•্āϤ āύāĻ•্āϏা āĻāĻ–āύ āφঁāĻ•ি āĻŦৈāĻĻ্āϝুāϤিāĻ• āϜেāύেā§°েāϟ⧰⧰ āĻ…āύ্āϤ⧰্āύিāĻšিāϤ āύীāϤি āφ⧰ু āĻ•াāĻŽ āĻŦ্āϝাāĻ–্āϝা āϕ⧰āĻ•। āĻŦ্ā§°াāϛ⧰ āĻ•াāĻŽ āĻ•ি? )

Answer:-

17. When does an electric short circuit occur?

( āĻŦৈāĻĻ্āϝুāϤিāĻ• āĻļ্āĻŦā§°্āϟ āϚাā§°্āĻ•িāϟ āĻ•েāϤিāϝ়া āĻšāϝ়? )

Answer:-

18. What is the function of an earth wire? Why is it necessary to earth metallic appliances?

(āĻĒৃāĻĨিā§ąীā§° āϤাঁā§°ā§° āĻ•াā§°্āϝ্āϝ āĻ•ি? āϧাāĻ¤ā§ąীāϝ় āϏঁāϜুāϞিāĻŦোā§° āĻĒৃāĻĨিā§ąীāϤ āĻĨāĻ•াāϟো āĻ•িāϝ় āĻĒ্ā§°āϝ়োāϜāύীāϝ়?)

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