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Which characteristic of sound is affected due to the larger surface of a school bell?
Concept: Characteristics of Sound >> Loudness and Intensity
Calculate the distance covered by the Ultrasonic wave having a velocity of 1.5 kms-1 in 14 s, when it is received after reflection by the receiver of the SONAR.
Concept: Echo >> Use of Echoes
We are able to see the T.V. channels clearly when we set T.V. on auto-tuning.
- Which phenomemon led to the clear visibility of the channels, due to auto-tuning?
- Define the above phenomenon mentioned by you.
- Give any one more example of this phenomenon.
Concept: Resonance (a special case of forced vibrations)
When the stem of vibrating tuning fork is pressed on a table, the tabletop starts vibrating. These vibrations are definitely an example of ______.
Concept: Forced Vibrations
Rohan conducted experiments on echo in different media. He observed that a minimum distance of 'x' meters is required for the echo to be heard in oxygen and 'y' meters in benzene. Compare 'x' and 'y'. Justify your answer.
Speed of sound in oxygen: 340 ms-1
Speed of sound in benzene: 200 ms-1
Concept: Echo

In the above diagram Lata stands between two cliffs and claps her hands.
Determine the time taken by her to hear the first echo. Speed of sound in air 320 ms-1.
Concept: Echo >> Determination of Speed of Sound by the Method of Echo
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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: Resonance (a special case of forced vibrations) >> Demonstration of Resonance
Give one reason for the use of ultrasonic waves in echo depth sounding.
Concept: Echo >> Use of Echoes
An electric bulb of 300Ω draws a current of 0.4 A. Calculate the power of the bulb and the potential difference at its ends.
Concept: Electro-Motive Force of a Cell
State two causes of energy loss in a transformer.
Concept: Potential and Potential Difference
The V-I graph for a series combination and for a parallel combination of two resistors is shown in the figure below. Which of the two A or B. represents the parallel combination? Give reasons for your answer.

Concept: Resistance of a System of Resistors >> Resistors in Series
The music system draws a current of 400 mA when connected to a 12 V battery.
- What is the resistance of the music system?
- The music system if left playing for several hours and finally the battery voltage drops and the music system stops playing when the current drops to 320 mA. At what battery voltage does the music system stop playing?
Concept: Ohm's Law >> Ohmic and Non-ohmic Resistors
Calculate the quantity of heat produced in a 20 Ω resistor carrying 2.5 A current in 5 minutes.
Concept: Potential and Potential Difference
A battery of emf 12 V and internal resistance 2 Ω is connected with two resistors A and B of resistance 4 Ω and 6 Ω respectively joined in series.

Find:
1) Current in the circuit
2) The terminal voltage of the cell
3) The potential difference across 6Ω Resistor
4) Electrical energy spent per minute in the 4Ω resistor.
Concept: Potential and Potential Difference
What happens to the resistivity of semiconductor with the increase of temperature?
Concept: Internal Resistance of a Cell
Find the equivalent resistance between points A and B.

Concept: Resistance of a System of Resistors >> Resistors in Series
At what frequency is AC supplied to residential houses?
Concept: Electrical Power
The relationship between the potential difference and the current in a conductor is stated in the form of a law.
1) Name the law.
2) What does the slope of V-I graph for a conductor represent?
3) Name the material used for making the connecting wire.
Concept: Ohm's Law

