With linear phased array transducers the outer crystals are excited ______ than the inner crystals.

• A. Later
• B. Earlier
• C. Simultaneously
• D. Not at all

Answer: (B)

In a linear phased array, beam shaping relies on timing each element so that the waves converge in phase at the focal point. For a target point in front of the array, the outer elements are physically farther from that point, so their emitted waves take longer to reach the focus. To synchronize arrival times, those outer elements must be excited earlier than the inner ones, compensating for the longer travel path. If the outer elements were fired later, their waves would arrive out of phase and the focus would degrade; firing simultaneously would not correct the path-length differences, and not emitting from the outer elements would prevent proper focusing.