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1. Electromagnetism 2. Magnetic Effects of an Electric Current 3. Electromagnetic Induction 1. When the current flows through a straight conductor: (a) It behaves like a magnet. (b) The magnitude of magnetic intensity is directly proportional to the magnitude of current flowing through the conductor. (c) The magnetic field set up by the conductor is at right angles to the direction of the flow of current. (d) The direction of magnetic field depends upon the direction of the flow of current. 2. Ampere s Swimming Rule : Imagine a swimmer (always looking towards magnetic needle), swimming in the direction of current, such that current enters from his feet and leaves from his head. Then, the direction in which left hand of swimmer points gives the direction of the north pole of magnetic needle. 3. Properties of magnetic lines of force around straight conductor carrying current : (1) The magnetic lines of force are in the form of concentric circles. (2) The plane of magnetic lines of force is at right angles to the direction of the current. (3) The direction of magnetic lines of force depends upon the direction of current. (4) On increasing the magnitude of current, the number of magnetic lines of force increases. Class-X 1 Key points
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