A rock band\'s music has an average sound intensity level of 101 dB. What would

Question

A rock band's music has an average sound intensity level of 101 dB. What would the average level be if the intensity was reduced by each of the following factors.
(a) a factor of 1/2 in dB
(b) a factor of 1/1,000 in dB

Light is incident on a plane mirror at an angle of 27° relative to the normal. What is the angle of reflection?

Light is incident on a plane mirror at an angle of 44° relative to its surface. What is the angle of reflection?

How much longer must the minimum length of a plane mirror be for a 6 ft 5 in man to see his complete head-to-toe image than for a 5 ft 2 in woman to do so?


What is the speed of light in air? in m/s

Explanation / Answer

Given Intensity level of sound, = 101 dB a) If I is reduced to 1/2, then the equation for sound level becomes     = 10 log (I / Io)     = 10 log ((I/2) / Io)    101 dB = 10 log (I /2 Io)    log ( I /2 Io) = 101 dB / 10 = 10.1 dB           I = 2 Io 1010.1 = 2 *(1.0 *10^-12 W/ m^2) *1010.1           I = 2.5 *10^-2 W/ m^2 b) If I is reduced to 1/1000 , then the equation for sound level becomes     = 10 log (I / Io)     = 10 log ((I/1000) / Io)    101 dB = 10 log (I /1000 Io)    log ( I /1000 Io) = 101 dB / 10 = 10.1 dB           I =1000* Io 1010.1 = 1000 *(1.0 *10^-12 W/ m^2) *1010.1           I =12.5 W/ m^2 Angle of incidence is , i = 270 From laws of reflection, angle of incidence = angle of reflection so,  angle of reflection(r) relative to the normal =270 The imcident ray , reflected ray and the normal at the point of incidence lie in the same plane Angle of incidence is , i = 440 From laws of reflection, angle of incidence = angle of reflection so,  angle of reflection(r) relative to the normal =440 The imcident ray , reflected ray and the normal at the point of incidence lie in the same plane * Post only one question for single post* The imcident ray , reflected ray and the normal at the point of incidence lie in the same plane Angle of incidence is , i = 440 From laws of reflection, angle of incidence = angle of reflection so,  angle of reflection(r) relative to the normal =440 The imcident ray , reflected ray and the normal at the point of incidence lie in the same plane Angle of incidence is , i = 440 From laws of reflection, angle of incidence = angle of reflection so,  angle of reflection(r) relative to the normal =440 The imcident ray , reflected ray and the normal at the point of incidence lie in the same plane The imcident ray , reflected ray and the normal at the point of incidence lie in the same plane

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