As we know that intensity of sound is defined as power received per unit area
so here the power of source is given as

distance of microphone is given as

now if loudspeaker is considered as spherical source then we will have


here
r = d = 60 m


Answer:
The minimum difference between the lengths of the two tubes should be 0.385 meters.
Explanation:
As we known that for any two waves to arrive in phase at any point the difference in the path traveled by the waves should be an integral multiple of the wavelength of the wave.
Mathematically we can write:

For the given wave we have

Applying values we get

Thus the minimum difference in the lengths of the tubes can be obtained by putting the value of n = 1

Answer:
C. Burning coal tends to harm the environment more than using solar panels.
Explanation:
When coal is burned, it reacts with the oxygen in the air. This reaction converts the stored potential energy, which turns into thermal energy, which is released as heat. But it also produces methane and carbon dioxide which is released into the air.
Option (C) is correct that the majority of the elements on the periodic table are metals.
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