Of the piezoelectric materials listed below, the most efficient sound transmitter is:

• A. Lithium sulfate
• B. Barium titanate
• C. Quartz
• D. Silver oxide

Answer: (B)

The efficiency of a piezoelectric transmitter depends on how well the material converts electrical energy into mechanical energy, which is governed by the electromechanical coupling factor and piezoelectric coefficients. Barium titanate is a ferroelectric ceramic with relatively high piezoelectric coefficients and a stronger coupling factor than the other materials listed, so it can convert drive electrical energy into acoustic energy more effectively. Quartz has excellent frequency stability and low losses, but its coupling is smaller, making it less efficient for transmitting energy. Lithium sulfate isn’t a strong transmitter material due to lower coupling and related losses. Silver oxide isn’t piezoelectric, so it cannot act as a transmitter. Therefore, barium titanate is the best choice among these for efficient sound transmission.