Decibel is a unit to measure:

Explanation:

• The decibel (dB) is a logarithmic unit used to measure sound level.
• It is also widely used in electronics, signals and communication.
• In ordinary usage, specification of the intensity of a sound implies a comparison of the intensity of the sound with that of a sound just perceptible to the human ear.
• In simple terms, the dB is the ratio between two power levels expressed in logarithmic terms with relation to some reference level.
• For example, if given two known power levels, P2 and P1, the relative value of P2 with respect to P1 in dB is given by:
  • dB = 10 log 10 (P2/P1)
• Noise levels below 35–40 dB are usually necessary for a good night’s sleep.
• A busy office may be about 60 dB while the noise level on a footpath beside a busy road might be approximately 75 dB.
• A departing jumbo jet may result in 120 dB being recorded along the runway.
• Ohm is the SI unit of electrical resistance, transmitting a current of one ampere when subjected to a potential difference of one volt.
• Joule, unit of work or energy in the International System of Units (SI); it is equal to the work done by a force of one newton acting through one metre.
• Ampere is a unit of electric current equal to a flow of one coulomb per second.