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The velocity ratio of a single movable pulley is always 2.
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The velocity ratio of a combination of n movable pulleys with a fixed pulley is always 2n.
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The velocity ratio of a block and tackle system is always equal to the number of strands of the tackle supporting the load.
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What is the colour code for the insulation on the live wire?
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A power circuit uses a cable having three different wires. Name the three wires of the cable.
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State two circumstances when one may get an electric shock from an electrical gadget. What preventive measure must be provided with the gadget to avoid it?
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Explain the meaning of the term e.m.f. of a cell.
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Name three factors on which the magnitude of force on a current carrying conductor placed in a magnetic field depends and state how does the force depend on the factors stated by you.
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State condition when magnitude of force on a current carrying conductor placed in a magnetic field is zero?
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State condition when magnitude of force on a current carrying conductor placed in a magnetic field is maximum?
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Name and state the law which is used to determine the direction of force on a current carrying conductor placed in a magnetic field.
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How will the direction of force be changed, if the current is reversed in the conductor placed in a magnetic field?
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State the unit of magnetic field in terms of the force experienced by a current carrying conductor placed in a magnetic field
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A flat coil ABCD is freely suspended between the pole of U-shaped permanent magnet with the plane of coil parallel to the magnetic field.
What happens when a current is passed in the coil?
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A coil ABCD mounted on an axle is placed between the poles N and S of a permanent magnet as shown in Figure.

- In which direction will the coil begin to rotate when current is passed through the coil in direction ABCD by connecting a battery at the ends A and D of the coil?
- Why is a commutator necessary for continuous rotation of the coil?
- Complete the diagram with commutator, etc. for the flow of current in the coil?
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How is the refractive index of a medium related to the real and apparent depths of an object in that medium?
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Prove that Refractive index = `"Real depth"/"Apparent depth"`.
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Water in a pond appears to be only three-quarters of its actual depth.
- What property of light is responsible for this observation? Illustrate your answer with the help of a ray diagram.
- How is the refractive index of water calculated from its real and apparent depth?
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A student puts his pencil into an empty trough and observes the pencil from the position as indicated in
- What change will be observed in the appearance of the pencil when water is poured into the trough?
- Name the phenomenon which accounts for the above stated observation.
- Complete the diagram showing how the student’s eye sees the pencil through water.
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An object placed in one medium when seen from the other medium, appears to be vertically shifted. Name two factors on which the magnitude of shift depends and state how does it depend on them.
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