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What energy conversion takes place during the working of a d c motor?
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State the factors that can increase the speed of rotation of the coil in a D.C. motor.
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State the energy change that takes’place in a D. C. motor.
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State the principle of a D. C. motor.
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State the position of armature coil relative to the direction of magnetic field, in a D. C. motor when the deflecting couple acting an the coil is maximum.
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State the position of armature coil relative to the direction of magnetic field, in a D. C. motor when the deflecting couple acting and the coil is minimum.
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What is dynomo (a.c. generator)? State the principle on which it works.
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The primary windings of a step-up transformer are usually made of thicker wire than the secondary. Explain.
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State important properties (or characteristics) of magnetic lines of force around a straight conductor.
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State the factors, on which depends the magnitude of the force acting on current carrying conductor, when it is kept in a magnetic field perpendicular to it.
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A current-carrying solenoid is suspended so as to freely rotate in a horizontal plane. State in what direction will it rest. Give a reason for your answer.
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When a solenoid that is carrying current is freely suspended, it comes to rest in a particular direction. Why does this happen?
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What are the factors that govern the magnitude of force acting on a current carrying conductor which is freely suspended in a magnetic field?
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Point out three differences between an electromagnet and a bar (or permanent) magnet.
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State and explain Maxwell’s Cork Screw Rule.
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(i) A straight wire conductor passes vertically through a piece of cardboard sprinkled with iron filings. Copy the diagram and show the setting of iron filings when a current is passed through the wire in the upward direction and the cardboard is tapped gently. Draw arrows to represent the direction of the magnetic field lines.
(ii) Name the law which helped you to find the direction of the magnetic field lines.
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State the function of a split ring in D.C. motor.
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How does a magnetic field set up by a solenoid change when cross-sectional area of solenoid is increased?
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What is heat? What is the S. I. unit of heat?
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What are other units of heat? Name and define them.
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State the condition for the flow of heat energy from one body to another.
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