If the output of the machine is increased by 20 dB, the beam intensity increases by how much?

• A. 100 times
• B. 20 times
• C. 1,000,000 times
• D. 10 times

Answer: (A)

A 20 dB change corresponds to a 100-fold increase in intensity because decibels relate to intensity by ΔdB = 10 log10(I2/I1). Solving for the ratio gives I2/I1 = 10^(ΔdB/10) = 10^(20/10) = 100. So the beam intensity becomes 100 times larger. In this logarithmic scale, a 10 dB change equals a 10x change, a 60 dB change would be a 1,000,000x change, and so on, which is why 100x is the correct interpretation for a 20 dB increase.