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In the given diagram, a vibrating tuning fork is kept near the mouth of a burette filled with water. The length of the air column is adjusted by opening the tap of the burette. At a length of 5 cm of the air column, a loud sound is heard
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- Name the phenomenon illustrated by the above experiment.
- Why is a loud sound heard at this particular length?
- If the present tuning fork is replaced with a tuning fork of higher frequency, should the length of the air column increase or decrease to produce a loud sound? Give a reason.
Concept: undefined >> undefined
Study the diagram:

- Calculate the total resistance of the circuit.
- Calculate the current drawn from the cell.
- State whether the current through 10 Ω resistor is greater than, less than or equal to the current through the 12 Ω resistor.
Concept: undefined >> undefined
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Name the radiations that are emitted during the decay of a nucleus, which has highest penetrating power?
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Does the emission of gamma radiation result in a change in the mass number?
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A radioactive nucleus X emits an alpha particle followed by two beta particles to form nucleus Y.
- With respect to the element X, where would you position the element Y in the periodic table?
- What is the general name of the elements X and Y?
- If the atomic number of Y is 80 then what is the atomic number of X?
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Name the type of energy (kinetic energy K or potential energy U) possessed in the following case:
A moving cricket ball
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Name the type of energy (kinetic energy K or potential energy U) possessed in the following case:
A compressed spring
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Name the type of energy (kinetic energy K or potential energy U) possessed in the following case:
A moving bus
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Explain the meaning of the term internal resistance of a cell.
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The diagram in Figure shows a cell of e.m.f. ε = 4 volt and internal resistance r = 2 ohm connected to an external resistance R = 8 ohm. The ammeter A measures the current in the circuit and the voltmeter V measures the terminal voltage across the cell. What will be the readings of the ammeter and voltmeter when
- the key K is open, and
- the key K is closed

Concept: undefined >> undefined
A battery of e.m.f. 6.0 V supplies current through a circuit in which the resistance can be changed. A high resistance voltmeter is connected across the battery. When the current is 3 A, the voltmeter reads 5.4 V. Find the internal resistance of the battery.
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A radioactive source emits three type of radiations.
From which part of the atom do these radiations come?
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Define the power of a lens.
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Ranbir claims to have obtained an image twice the size of the object with a concave lens. Is he correct? Give a reason for your answer.
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The lens mentioned in 6(b) above is of focal length 25cm. Calculate the power of the lens.
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A resistor of 6 Ω is connected in series with another resistor of 4 Ω. A potential difference of 20 V is applied across the combination. Calculate
- the current in the circuit and
- the potential difference across the 6 Ω resistor.
Concept: undefined >> undefined
A tank of water is viewed normally from above.
- State how does the depth of tank appear to change.
- Draw a labelled ray diagram to explain your answer.
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An object in a denser medium when viewed from a rarer medium appears to be raised. The shift is maximum for ______.
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Define the term focal length of a lens.
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State the condition for the following a lens has both its focal lengths equal .
Concept: undefined >> undefined

