Which statement about finite-energy signals is true?

• A. It has finite energy and finite power
• B. It has finite energy but zero average power
• C. It has infinite energy
• D. It has finite power but infinite energy

Answer: (B)

Finite-energy signals carry a finite total energy, meaning the integral of the squared magnitude over all time is finite. Because that energy is confined to a limited span of time, when you average it over longer and longer observation intervals the energy-per-unit-time shrinks to zero. In other words, a finite-energy signal has finite energy but zero average power. This aligns with the idea that a signal can deliver a finite amount of energy, but as you watch it for longer and longer, the average power tends to vanish. The other possibilities don’t fit: finite energy cannot coincide with a nonzero finite average power, nor can it involve infinite energy, and finite power with infinite energy conflicts with the finite-energy condition.