The sound level of one person talking at a certain distance from you is 80 dB. If she is joined by 2 more friends, and all of them are talking (incoherently) at the same time as loudly as she is, what sound level are you being exposed to? a)

Explanation:

sound level scale is logarithmic which is given by the following formula

L = 10 log I / I₀ where I₀ = 10⁻¹² W / m² s

80 = 10 log I / 10⁻¹²

8 = log I / 10⁻¹²

I / 10⁻¹² = 10⁸

I = 10⁻⁴ W / m² .s

for three person the intensity becomes three times ie

3 x 10⁻⁴

L = 10 log 3 x 10⁻⁴ / 10⁻¹²

= 10 log 3 x 10⁸

= 10 ( 8 + log 3 )

= 10 ( 8 + .477 )

= 84.77 dB .

a electromagnetic waves