The power level at the output of a device is 50 dBm. Identify the absolute value of power from the following options.

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ALP CBT 2 Electronic Mechanic Previous Paper: Held on 21 Jan 2019 Shift 1

Answer 1

Concept:

A dBm is a unit of measurement used to indicate the ratio of power level with respect to a fixed reference level.

With dBm, the reference level is 1 mW (milliwatt).

Power in dBm is expressed as:

\(P(dBm)=10log_{10}(\frac{P}{1m})\)

P = Power to be expressed in dBm

Application:

Given Output Power in dBm = 50

\(50=10log_{10}(\frac{P}{1m})\)

\(5=log_{10}(\frac{P}{1m})\)

Taking antilog on both sides, we get:

\(10^5=\frac{P}{1m}\)

P = 10⁵ × 10^-3 W

P = 100 W

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