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Waves produced on the surface of the water are formed to move with a velocity of 24 ms−1. If the wavelength of these waves equals 20 cm. find the
(i) frequency (no. of waves produced per second)
(ii) the time period (i.e. the time required to produce one wave) for these waves.
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(i) A man stands at a distance of 68 m from a cliff and fires a gun. After what time interval will he hear the echo, if the speed of sound in air is 340 ms−1?
(ii) If the man had been standing at a distance of 12 m from the cliff would he have heard a clear echo?
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A sound wavelength of 0.332 m has a time period of 10−3 s. If the time period is decreased to 10−4 s, calculate the wavelength and frequency of the new wave.
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State three differences between heat and temperature.
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A ray of light is incident at 45° on an equilateral prism in the diagram below.

- Name the phenomenon exhibited by the ray of light when it enters and emerges out of the prism.
- State the cause of the above phenomenon mentioned by you.
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Two identical marbles A and B are rolled down along Path 1 and Path 2 respectively.
Path 1 is frictionless and Path 2 is rough.
- Which marble will surely reach the next peak?
- Along which path/s the mechanical energy will be conserved?
- Along which path/s is the law of conservation of energy obeyed?
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Given below is a circuit to study the magnetic effect of electric current. ABCD is a cardboard kept perpendicular to the conductor XY. A magnetic compass is placed at the point P of the cardboard. P1 and P2 are the positions of the magnetic compass, before and after passing a current through XY respectively.
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- Name the rule that is used to predict the direction of deflection of the magnetic compass.
- State the direction of current in the conductor (X to Y or Y to X) when the circuit is complete.
- If resistance R is increased, then what will be the effect on the magnetic lines of force around the conductor?
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A moment of couple has a tendency to rotate the body in an anticlockwise direction. Then the moment of the couple is taken as ______.
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Mixture of red + blue + green is passed through a convex lens as shown in the diagram below. State whether the ray passes through a single point or through different points on the principal axis after refraction.

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When sunlight passes through water droplets in the atmosphere it gets dispersed into its constituent colours forming a rainbow. A similar phenomenon is observed when white light passes through a prism.
Which colour will show the maximum angle of deviation and which colour will show the minimum angle of deviation?
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When sunlight passes through water droplets in the atmosphere it gets dispersed into its constituent colours forming a rainbow. A similar phenomenon is observed when white light passes through a prism.
Instead of sunlight, a green-coloured ray is passed through a glass prism. What will be the colour of the emergent ray?
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How is mechanical advantage related to velocity ratio for a practical machine?
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Give two reasons for a machine not to be 100% efficient?
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What does the positive and negative sign of potential convey?
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Find the potential difference required to flow a current of 300 mA in a wire of resistance 20 Ω.
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State the couple's effect on a body.
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If the power of a motor is 100 kW, at what speed can it raise a load of 50,000 N?
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To which wire should the fuse be connected?
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Explain the meaning of the student 'current rating of a fuse is 5A'.
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