Chapter 13
āĻ āϧ্āϝাāϝ় ā§§ā§Š
Magnetic Electric Current
āĻুāĻŽ্āĻŦāĻীāϝ় āĻŦৈāĻĻ্āϝুāϤিāĻ āĻĒ্ā§°āĻŦাāĻš
EXERCISES
āĻŦ্āϝাāϝ়াāĻŽ
1. āϤāϞ⧰ āĻোāύāĻোā§ąে āĻĻীāĻāϞ āĻĒোāύ āϤাঁā§°ā§° āĻāĻā§°ā§° āĻুāĻŽ্āĻŦāĻীāϝ় āĻ্āώেāϤ্ā§°āĻāύ āϏāĻ িāĻāĻাā§ąে āĻŦā§°্āĻŖāύা āĻā§°িāĻে?
(a) The field consists of straight lines perpendicular to the wire,
(āĻ) āĻ্āώেāϤ্ā§°āĻāύ āϤাঁā§°ā§° āϞāĻāϤ āϞāĻŽ্āĻŦāĻাā§ąে āĻĨāĻা āϏ⧰āϞ⧰েāĻাā§°ে āĻāĻ িāϤ,
(b) The field consists of straight lines parallel to the wire.
(āĻ) āĻ্āώেāϤ্ā§°āĻāύ āϤাঁā§°ā§° āϏāĻŽাāύ্āϤ⧰াāϞāĻাā§ąে āϏ⧰āϞ⧰েāĻাā§°ে āĻāĻ িāϤ।
(āĻ) āϤাঁā§°ā§° āĻĒā§°া āĻā§āĻĒāϤ্āϤি āĻšোā§ąা ā§°েāĻĄিāϝ়েāϞ ā§°েāĻাā§°ে āĻ্āώেāϤ্ā§°āĻāύ āĻāĻ িāϤ।
(āĻ) āϤাঁā§°ā§° āĻāĻĒā§°āϤ āĻেāύ্āĻĻ্ā§° āĻā§°ি āϏāĻŽāĻেāύ্āĻĻ্ā§°িāĻ āĻŦৃāϤ্āϤ⧰ে āĻ্āώেāϤ্ā§°āĻāύ āĻāĻ িāϤ।
2. The phenomenon of electromagnetic induction is
⧍/ āĻŦিāĻĻ্āϝুā§āĻুāĻŽ্āĻŦāĻীāϝ় āĻĒ্ā§°ā§°োāĻāύাā§° āĻĒā§°িāĻāĻāύাāĻো āĻš’āϞ
(āĻ) āĻোāύো āĻŦāϏ্āϤুāĻ āĻাā§°্āĻ āĻā§°াā§° āĻĒ্ā§°āĻ্ā§°িāϝ়া।
(āĻ) āĻুāĻŖ্āĻĄāϞীā§° āĻŽাāĻেā§°ে āĻĒাā§° āĻšৈ āϝোā§ąা āĻŦিāĻĻ্āϝুā§ āĻĒ্ā§°āĻŦাāĻšā§° āĻĢāϞāϤ āĻুāĻŽ্āĻŦāĻীāϝ় āĻ্āώেāϤ্ā§° āĻā§āĻĒāύ্āύ āĻā§°া āĻĒ্ā§°āĻ্ā§°িāϝ়া।
(āĻ) āĻুāĻŽ্āĻŦāĻ āĻā§°ু āĻুāĻŖ্āĻĄāϞীā§° āĻŽাāĻāϤ āĻāĻĒেāĻ্āώিāĻ āĻāϤিā§° āĻŦাāĻŦে āĻুāĻŖ্āĻĄāϞীāϤ āĻĒ্ā§°ā§°োāĻিāϤ āĻŦিāĻĻ্āϝুā§ āĻĒ্ā§°āĻŦাāĻš āĻā§āĻĒāύ্āύ āĻā§°া।
(āĻ) āĻŦৈāĻĻ্āϝুāϤিāĻ āĻŽāĻā§°ā§° āĻāĻা āĻāĻāϞ āĻূā§°োā§ąাā§° āĻĒ্ā§°āĻ্ā§°িāϝ়া।
3. The device used for producing electric current is called a
ā§Š) āĻŦৈāĻĻ্āϝুāϤিāĻ āĻĒ্ā§°āĻŦাāĻš āĻā§āĻĒāύ্āύ āĻā§°িāĻŦāϞৈ āĻŦ্āĻ¯ā§ąāĻšাā§° āĻā§°া āϝāύ্āϤ্ā§°āĻোāĻ āĻ āĻŦোāϞা āĻšāϝ়
(āĻ) āĻেāύেā§°েāĻā§°।
(āĻ) āĻেāϞāĻেāύ’āĻŽিāĻাā§°।
(āĻ) āĻāĻŽিāĻাā§°।
(āĻ) āĻŽāĻā§°।
4. The essential difference between an AC generator and a DC generator is that
ā§Ē/ āĻ āĻি āĻেāύেā§°েāĻā§° āĻā§°ু āĻĄি āĻি āĻেāύেā§°েāĻā§°ā§° āĻŽাāĻāϤ āĻĨāĻা āĻ āĻĒā§°িāĻšাā§°্āϝ āĻĒাā§°্āĻĨāĻ্āϝāĻো āĻš’āϞ
(a) AC generator has an electromagnet while a DC generator has permanent magnet.
(āĻ) āĻ āĻি āĻেāύেā§°েāĻā§°āϤ āĻŦিāĻĻ্āϝুā§āĻুāĻŽ্āĻŦāĻ āĻĨাāĻে āĻāύāĻšাāϤে āĻĄি āĻি āĻেāύেā§°েāĻā§°āϤ āϏ্āĻĨাāϝ়ী āĻুāĻŽ্āĻŦāĻ āĻĨাāĻে।
(āĻ) āĻĄিāĻি āĻেāύেā§°েāĻā§°ে āĻ āϧিāĻ āĻāϞ্āĻেāĻ āĻā§āĻĒāύ্āύ āĻā§°িāĻŦ।
(āĻ) āĻ āĻি āĻেāύেā§°েāĻā§°ে āĻ āϧিāĻ āĻāϞ্āĻেāĻ āĻā§āĻĒāύ্āύ āĻā§°িāĻŦ।
(āĻ) āĻ āĻি āĻেāύেā§°েāĻā§°āϤ āϏ্āϞিāĻĒ ā§°িং āĻĨাāĻে āĻāύāĻšাāϤে āĻĄি āĻি āĻেāύেā§°েāĻā§°āϤ āĻāĻŽিāĻāĻেāĻā§° āĻĨাāĻে।
5. At the time of short circuit, the current in the circuit
ā§Ģ) āĻļ্āĻŦā§°্āĻ āĻাā§°্āĻিāĻā§° āϏāĻŽāϝ়āϤ āĻাā§°্āĻিāĻāϤ āĻĨāĻা āĻাā§°েāĻŖ্āĻ
(a) reduces substantially.
(āĻ) āϝāĻĨেāώ্āĻ āĻĒā§°িāĻŽাāĻŖে āĻš্ā§°াāϏ āĻĒাāϝ়।
(āĻ) āϏāϞāύি āύāĻšāϝ়।
(āĻ) āĻŦāĻšু āĻĒā§°িāĻŽাāĻŖে āĻŦৃāĻĻ্āϧি āĻĒাāϝ়।
(āĻ) āĻ āĻŦিā§°āϤāĻাā§ąে āϤাā§°āϤāĻŽ্āϝ āĻāĻে।
6. State whether the following statements are true or false.
ā§Ŧ) āϤāϞāϤ āĻĻিāϝ়া āĻŦāĻ্āϤāĻŦ্āϝāĻŦোā§° āϏঁāĻা āύে āĻŽিāĻা āϏেāĻāĻো āĻোā§ąা।
(āĻ) āĻŦৈāĻĻ্āϝুāϤিāĻ āĻŽāĻā§° āĻāĻাāĻ āϝাāύ্āϤ্ā§°িāĻ āĻļāĻ্āϤিāĻ āĻŦৈāĻĻ্āϝুāϤিāĻ āĻļāĻ্āϤিāϞৈ ā§°ূāĻĒাāύ্āϤ⧰িāϤ āĻā§°ে।
(āĻ) āĻāĻা āĻŦৈāĻĻ্āϝুāϤিāĻ āĻā§āĻĒাāĻĻāĻে āĻŦিāĻĻ্āϝুā§āĻুāĻŽ্āĻŦāĻীāϝ় āĻĒ্ā§°ā§°োāĻāύাā§° āύীāϤিā§° āĻāĻĒā§°āϤ āĻাāĻŽ āĻā§°ে।
(āĻ) āĻাā§°েāĻŖ্āĻ āĻāĻĸ়িāϝ়াāĻ āύিāϝ়া āĻĻীāĻāϞ āĻŦৃāϤ্āϤাāĻাā§° āĻুāĻŖ্āĻĄāϞীā§° āĻেāύ্āĻĻ্ā§°āϤ āĻĨāĻা āĻ্āώেāϤ্ā§°āĻāύ āϏāĻŽাāύ্āϤ⧰াāϞ āϏ⧰āϞ⧰েāĻা āĻš’āĻŦ।
(āĻ) āϏেāĻāĻীāϝ়া āĻāύāĻুāϞেāĻāύ āĻĨāĻা āϤাঁā§° āĻšৈāĻে āϏাāϧাā§°āĻŖāϤে āĻŦৈāĻĻ্āϝুāϤিāĻ āϝোāĻাāύ⧰ āĻীā§ąāύ্āϤ āϤাঁā§°।
7. List two methods of producing magnetic fields.
ā§) āĻুāĻŽ্āĻŦāĻীāϝ় āĻ্āώেāϤ্ā§° āĻā§āĻĒāύ্āύ āĻā§°াā§° āĻĻুāĻা āĻĒāĻĻ্āϧāϤি āϤাāϞিāĻাāĻুāĻ্āϤ āĻā§°া।
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.
ā§Ž/ āĻ’āϞেāύ’āĻāĻĄে āĻুāĻŽ্āĻŦāĻā§° āĻĻā§°ে āĻেāύেāĻৈ āĻāĻā§°āĻŖ āĻā§°ে? āĻŦাā§° āĻুāĻŽ্āĻŦāĻā§° āϏāĻšাāϝ়āϤ āĻাā§°েāĻŖ্āĻ āĻāĻĸ়িāϝ়াāĻ āύিāϝ়া āĻ’āϞেāύ’āĻāĻĄā§° āĻāϤ্āϤ⧰ āĻā§°ু āĻĻāĻ্āώিāĻŖ āĻŽেā§°ু āύিā§°্āĻŖāϝ় āĻā§°িāĻŦ āĻĒাā§°িāĻŦāύে? āĻŦ্āϝাāĻ্āϝা āĻā§°া.
9. When is the force experienced by a current-carrying conductor placed in a magnetic field largest?
⧝) āĻুāĻŽ্āĻŦāĻীāϝ় āĻ্āώেāϤ্ā§°āϤ āϏ্āĻĨাāĻĒāύ āĻā§°া āĻŦিāĻĻ্āϝুā§ āĻĒ্ā§°āĻŦাāĻš āĻŦāĻšāύāĻাā§°ী āĻĒā§°িāĻŦাāĻšীāϝ়ে āĻ āύুāĻā§ą āĻā§°া āĻŦāϞ āĻেāϤিāϝ়া āĻāĻাāĻāϤāĻৈ āĻĄাāĻā§° āĻšāϝ়?
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?
ā§§ā§Ļ) āĻāϞ্āĻĒāύা āĻā§°āĻ āϝে āĻāĻĒুāύি āĻāĻা āĻোāĻ াāϤ āĻāĻা āĻŦেā§°āϤ āĻĒিāĻ ি āĻĻি āĻŦāĻšি āĻāĻে। āĻĒিāĻāĻĢাāϞ⧰ āĻŦেā§°ā§° āĻĒā§°া āϏāύ্āĻŽুāĻā§° āĻŦেā§°ā§° āĻĢাāϞে āĻ āύুāĻূāĻŽিāĻāĻাā§ąে āĻāϤি āĻā§°া āĻāĻা āĻāϞেāĻ্āĻ্ā§°āύ ā§°āĻļ্āĻŽি āĻāĻা āĻļāĻ্āϤিāĻļাāϞী āĻুāĻŽ্āĻŦāĻীāϝ় āĻ্āώেāϤ্ā§°ā§° āĻĻ্āĻŦাā§°া āĻāĻĒোāύাā§° āϏোঁāĻĢাāϞে āĻŦিāĻ্āϝুāϤ āĻšāϝ়। āĻুāĻŽ্āĻŦāĻীāϝ় āĻ্āώেāϤ্ā§°ā§° āĻĻিāĻļ āĻি?
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?
ā§§ā§§) āĻāĻা āĻŦৈāĻĻ্āϝুāϤিāĻ āĻŽāĻā§°ā§° āϞেāĻŦেāϞāϝুāĻ্āϤ āĻĄাāϝ়েāĻ্ā§°াāĻŽ āĻঁāĻিāĻŦ। āĻāϝ়াā§° āύীāϤি āĻā§°ু āĻাāĻŽ āĻā§°া āĻŦ্āϝাāĻ্āϝা āĻā§°া। āĻŦৈāĻĻ্āϝুāϤিāĻ āĻŽāĻā§°āϤ āĻāĻা āĻŦিāĻāĻ্āϤ āĻāĻāĻ িā§° āĻাā§°্āϝ্āϝ āĻি?
12. Name some devices in which electric motors are used.
⧧⧍) āĻāϞেāĻ্āĻ্ā§°িāĻ āĻŽāĻā§° āĻŦ্āĻ¯ā§ąāĻšাā§° āĻā§°া āĻিāĻুāĻŽাāύ āϝāύ্āϤ্ā§°ā§° āύাāĻŽ āϞিāĻা।
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?
ā§§ā§Š) āĻāύāĻুāϞেāĻেāĻĄ āϤাāĻŽā§° āϤাঁā§°ā§° āĻāĻা āĻুāĻŖ্āĻĄāϞী āĻেāϞāĻেāύ’āĻŽিāĻাā§°ā§° āϏৈāϤে āϏংāϝোāĻ āĻā§°া āĻšāϝ়। āϝāĻĻি āĻāĻা āĻŦাā§° āĻুāĻŽ্āĻŦāĻ (i) āĻুāĻŖ্āĻĄāϞীā§° āĻিāϤ⧰āϞৈ āĻ েāϞি āĻĻিāϝ়া āĻšāϝ়, (ii) āĻুāĻŖ্āĻĄāϞীā§° āĻিāϤ⧰⧰ āĻĒā§°া āĻāϞিāϝ়াāĻ āĻĻিāϝ়া āĻšāϝ়, (iii) āĻুāĻŖ্āĻĄāϞীā§° āĻিāϤ⧰āϤ āϏ্āĻĨāĻŦিā§° āĻā§°ি ā§°āĻা āĻšāϝ় āϤেāύ্āϤে āĻি āĻš’āĻŦ?
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.
ā§§ā§Ē) āĻĻুāĻা āĻŦৃāϤ্āϤাāĻাā§° āĻুāĻŖ্āĻĄāϞী A āĻā§°ু B āĻāĻোā§ąে āϏিāĻোā§° āĻāĻā§°āϤ āĻŦāύ্āϧ āĻā§°ি ā§°āĻা āĻšāϝ়। āϝāĻĻি āĻāĻāϞ A āϤ āĻĨāĻা āĻাā§°েāĻŖ্āĻ āϏāϞāύি āĻā§°া āĻšāϝ় āϤেāύ্āϤে āĻāĻāϞ B āϤ āĻিāĻু āĻাā§°েāĻŖ্āĻ āĻĒ্ā§°ā§°োāĻিāϤ āĻš’āĻŦāύে? āĻাā§°āĻŖ āĻĻিāϝ়āĻ।
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.
15. (i) āĻāĻা āĻĒোāύ āĻĒā§°িāĻŦাāĻšী āĻŦāĻšāύāĻাā§°ী āĻĒ্ā§°āĻŦাāĻšā§° āĻাā§°িāĻāĻĢাāϞে āĻā§āĻĒāύ্āύ āĻšোā§ąা āĻুāĻŽ্āĻŦāĻীāϝ় āĻ্āώেāϤ্ā§°, (ii) āĻāϝ়াā§° āϞāĻāϤ āϞāĻŽ্āĻŦāĻাā§ąে āĻĨāĻা āĻুāĻŽ্āĻŦāĻীāϝ় āĻ্āώেāϤ্ā§°āϤ āϏ্āĻĨাāĻĒāύ āĻā§°া āĻĒ্ā§°āĻŦাāĻš āĻŦāĻšāύāĻাā§°ী āĻĒোāύ āĻĒā§°িāĻŦাāĻšীāϝ়ে āĻ āύুāĻā§ą āĻā§°া āĻŦāϞ, āĻā§°ু ( iii) āĻুāĻŽ্āĻŦāĻীāϝ় āĻ্āώেāϤ্ā§°āϤ āĻূā§°্āĻŖāύ⧰ āĻĢāϞāϤ āĻুāĻŖ্āĻĄāϞীāϤ āĻĒ্ā§°ā§°োāĻিāϤ āĻŦিāĻĻ্āϝুā§ āĻĒ্ā§°āĻŦাāĻš।
16. Explain the underlying principle and working of an electric generator by drawing a labelled diagram. What is the function of brushes?
ā§§ā§Ŧ) āϞেāĻŦেāϞāϝুāĻ্āϤ āĻĄাāϝ়েāĻ্ā§°াāĻŽ āĻāĻāύ āĻঁāĻি āĻŦৈāĻĻ্āϝুāϤিāĻ āĻেāύেā§°েāĻā§°ā§° āĻ āύ্āϤ⧰্āύিāĻšিāϤ āύীāϤি āĻā§°ু āĻাāĻŽ-āĻাāĻā§° āĻŦিāώāϝ়ে āĻŦ্āϝাāĻ্āϝা āĻā§°া। āĻŦ্ā§°াāĻā§° āĻাā§°্āϝ্āϝ āĻি?
17. When does an electric short circuit occur?
ā§§ā§) āĻŦৈāĻĻ্āϝুāϤিāĻ āĻļ্āĻŦā§°্āĻ āĻাā§°্āĻিāĻ āĻেāϤিāϝ়া āĻšāϝ়?
18. What is the function of an earth wire? Why is it necessary to earth metallic appliances?
ā§§ā§Ž) āĻŽাāĻিā§° āϤাঁā§°ā§° āĻাā§°্āϝ্āϝ āĻি? āϧাāϤুā§° āϏঁāĻুāϞিāĻŦোā§° āĻŽাāĻিāϤ āϞāĻাāĻŦ āϞাāĻে āĻিāϝ়?