Asound is recorded at 19 decibels. what is the intensity of the sound?
1 x 10^-8.7 w/m^2
1 x 10^-10.1 w/m^2
1 x 10^-11.9 w/m^2
1 x 10^-9.4 w/m^2

is the intensity of the sound.

Option B

Explanation:

The range of sound intensity that people can recognize is so large (including 13 magnitude levels). The intensity of the weakest audible noise is called the hearing threshold. (intensity about ). Because it is difficult to imagine numbers in such a large range, it is advisable to use a scale from 0 to 100.

This is the goal of the decibel scale (dB).  Because logarithm has the property of recording a large number and returning a small number, the dB scale is based on a logarithmic scale. The scale is defined so that the hearing threshold has intensity level of sound as 0.

Where,

I = Intensity of the sound produced

= Standard Intensity of sound of 60 decibels =

So for 19 decibels, determine I as follows,

When log goes to other side, express in 10 to the power of that side value,

the maxium height is 34m/s

the answer is the first electromagnet (a). this is because it has more coils around the ferromagnetic material. increasing the number of coils increases the surface area in which the metal interacts with the current in the coil. this enables more atoms in the metal to become aligned hence becoming more magnetized.