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A square cardboard of side I and mass m ...

A square cardboard of side I and mass m is suspended from a horizontal axis XY as shown in figure. A single wire is wound along the periphery of board and carrying a clockwise current I. At t = 0, a vertical downward magnetic field of induction B is switched on. Find the minimum magnitude of B so that the board will be able to rotate up to horizontal level.

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The correct Answer is:
`[(mg)/(2Il)]`
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PHYSICS GALAXY - ASHISH ARORA-MAGNETIC EFFECTS OF CURRENT AND MAGNETISM-Practice Exercise
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  3. A square cardboard of side I and mass m is suspended from a horizontal...

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  10. A coil in the shape of an equilateral triangle of side 0.02 m is suspe...

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  11. A wire loop carrying I is placed in the x-yplane as shown in fig. (...

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  12. A coil of radius R carries current i1. Another concentric coil of radi...

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  13. A small coil C with N = 200 turns is mounted on one end of a balanc...

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  14. A uniform constant magnetic field B is directed at an angle of 45^(@) ...

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  15. Calculating the magnetic moment ( in Am^2) of a thin wire with a curre...

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  16. A flat circular coil with 10 turns of wire on it has a diameter 20mm a...

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  17. A coil al a moving Coil galvanometer twists through 90^@ when a curren...

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  18. A short bar magnet is placed in magnetic meridian with its north pole ...

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  19. A magnetic dipole of magnetic moment 6Am^(2) is lying in a horizontal ...

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  20. A coil of 50 turns and 10cm diameter is made out of a wire of resistiv...

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