9th Physics Chapter 8 Constructed response question
9th Physics Chapter 8 Constructed response question. We will answer only revised syllabus 9th class physics CROs.
8.1 Two bar magnets are stored in a wooden box. Label the poles of the magnets and identify P and Q objects.
Right Magnet
South (blue) pole is at top and North (red) pole is at the bottom
Left Magnet
South (blue) pole is at the bottom and North (red) pole is at the top
P and Q are non-magnetic or test rods used to detect the magnetic field
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8.2 A steel bar has to be magnetised by placing it inside a solenoid such that end A of a bar becomes N-pole and end B becomes S-pole. Draw circuit diagram of solenoid showing steel bar inside it.
When current flows through the solenoid, it produces magnetic field around its own axis. When we curl the fingers of our right hand in the direction of current flowing through the coils, our thumb points towards the North-pole of solenoid. When we place the steel bar inside the solenoid along its axis and current flows through the solenoid, end of steel bar facing the North-pole of solenoid becomes North-pole and end of steel bar facing the South-pole of solenoid becomes South-pole.
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8.3 Two bar magnets are laying as shown in the figure. A compass is placed a the middle of the gap. Its needle settles in the north-south direction. Label N and S poles of the magnets. Justify your answer by drawing fields lines.
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8.4 Electric current or motion of electrons produce magnetic field. Is the reverse process true, that is the magnetic field gives rise to electric current? If yes, give an example and describe it briefly.
Yes, the reverse process is true. a magnetic field can give rise to an electric current.
An electric generator works on this principle.
In an electric generator, when a coil is rotated in a magnetic field, the changing magnetic field induces an electric current in the coil, which produces electricity.
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8.5 Four similar solenoids are placed in a circle as shown in the figure. The magnitude of current in all of them should be the same. Show by diagram, the direction of current in anyone solenoid is switched OFF, the net magnetic field at the centre O is directed towards that solenoid. Explain your answer.
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Some important links are given below
