Answer:
All kinds of waves have the same fundamental properties of reflection, refraction, diffraction, and interference, and all waves have a wavelength, frequency, speed, and amplitude.
Explanation:
Sound level at distance of 15 m is given as 20 dB
so intensity at this distance is given as



now if we move closer to some some distance the sound level is now 50 dB
now the intensity is given as



now we know that



so now the distance from friend must be 47 cm
Answer:True
Explanation: The mechanical waves need a medium through which to transport energy because the perturbation travels inside of the medium so it needs molecules that connect elastically the displacement of the wave. For example the sound mainly uses the air molecules to transport the energy also the sound can be traveled in solid materials like metal rods.
The phenomenon of inducing voltage by changing the magnetic field around a conductor will be Electromagnetic Induction. Option B is correct.
<h3>What is the Faraday law of electromagnetic induction?</h3>
According to Faraday's law of electromagnetic induction, the rate of change of magnetic flux link with the coil is responsible for generating emf in the coil to result in the flow of amount of current .
So in order to increase the current, we need to increase the EMF;
so we can increase it by;
1) Increasing the number of turns
2) Increase the area of the loop
3) By moving the magnet faster
Hence, option B is correct.
To learn more about Faraday law of electromagnetic induction:
brainly.com/question/13369951
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