Explanation :
Absorption coefficient of a material determines how much sound is absorbed by the material.
To build a soundproof room, Heavy curtains and carpet can be used. They reduce reverberation.
Reverberation means an echoing sound which persists for some time. For example, when we bang on a huge piece of metal, we hear the reverberation even after we stop banging.
Hence, option (A) and (D) are correct.
<u>Answer</u>
48 Volts
<u>Explanation</u>
The question can be solve using the turn rule of a transformer that states;
Np/Ns = Vp/Vs
Where Np ⇒ number of turns in the primary coil.
Ns ⇒number of turns in the seconndary coil
Vp ⇒ primary voltage
Vs ⇒secondary voltage
Np/Ns = Vp/Vs
10/4 = 120/Vp
Vp = (120 × 4)/10
= 480/10
= 48 Volts
Answer:
A vacuum
Explanation:
Sound waves are examples of mechanical waves. Mechanical waves are waves which are transmitted through the vibrations of the particles in a medium.
For example, sound waves in air consist of oscillations of the air particles, which vibrate back and forth (longitudinal wave) along the direction of propagation of the wave itself.
Given this definition of mechanical wave, we see that such a wave cannot propagate if there is no medium, because there are no particles that would oscillate. Therefore, among the choices given, the following one:
a vacuum
represent the only situation in which a sound wave cannot propagate through: in fact, there are no particles in a vacuum, so the oscillations cannot occur. In all other cases, instead, sound waves can propagate.
