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OnlinePhysicsTutorial, (By : Sir Sarat Singh, M.Sc. B.Ed. PGDCA), Practice Qestions For COHSEM Exam., UNIT – III, MAGNETIC EFFECT OF CURRENT & MAGNETISM, 09 Marks, 1., Under what condition does a charge q moving with velocity v experience maximum force?, , 2., 3., 4., 5., 6., , 7., 8., 9., 10., , 11., 12., 13., , 14., , 1, , Two thin long parallel wires separated by a distance ‘b’ are carrying a current 1A each. Write, down the magnitude of the force per unit length by one wire on the other., 1, How can the range of an ammeter be increased?, 1, Find the magnetic moment of a circular current loop of length L and carrying a current I., 1, Electrons cannot be accelerated by cyclotron, why?, 1, A straight long wire carrying current of 2A is bent in the, form of a semi circle of arc length 3.14 m as shown in figure. Find the, magnitude and direction of the magnetic field at the centre ‘O’ in the, figure due to the current in the wire., 2, State the principle of moving coil galvanometer. Mention the use of radial magnetic field in a, galvanometer., 1+1=2, An alpha particle and a proton are projected simultaneously with same KE at right angles to the, direction of magnetic field. Compare the radii of curvature for the trajectories of both particles. 2, Distinguish between a magnet and a current loop., 1+1=2, Using Biot-Savart’s law, derive an expression for the magnetic field at the centre of a circular coil, of ‘n’ turns carrying current I., 3, Using Ampere’s circuital law, obtain an expression for the magnetic field due to infinitely long, straight wire carrying current., 3, Obtain an expression for magnetic dipole moment of a revolving electron in terms of angular, momentum and hence deduce Bohr magnetron., 2+1=3, Define the three elements of earth’s magnetism., OR, (Define (i) magnetic declination (ii) magnetic inclination and (iii) horizontal component of earth’s, magnetic field.), 1+1+1=3, Distinguish among paramagnetic ,diamagnetic and ferromagnetic substances., 3, , 15., , State Ampere’s circuital law. Obtain an expression for the magnetic field at a point inside a, solenoid carrying current by using Ampere’s circuital law., 1+4=5, , 16., , Explain with neat labelled diagram, the principle and working of cyclotron. Show that cyclotron frequency, is independent of speed of the charged particle., 3+2=5, Derive an expression for the force experienced by a current carrying straight conductor placed in a uniform, magnetic field. Under what condition is this force maximum? Name the rule that determines the direction of, this force., 3+1+1=5, Derive an expression for the force per unit length between two infinitely long straight parallel wires, carrying currents. Define one ampere from it and also define one coulomb., 3+1+1=5, , 17., , 18.