The amplifier range over which the unsaturated signal response increases in amplitude in proportion to the discontinuity surface area is the

• A. Sensitivity range
• B. Vertical linearity range
• C. Selectivity range
• D. Horizontal linearity range

Answer: (B)

Vertical linearity range focuses on how the signal’s amplitude responds on the vertical (amplitude) axis as the input signal changes. In the unsaturated portion of the amplifier’s dynamic range, the output amplitude increases in direct proportion to the input, and for a discontinuity this translates to the amplitude being proportional to the defect’s surface area. In other words, within this range doubling the defect area roughly doubles the reflected amplitude. Once the signal approaches saturation, the relationship becomes nonlinear and the proportionality no longer holds. Other ranges relate to different aspects—sensitivity is about detecting small signals, selectivity concerns distinguishing signals from noise, and horizontal linearity would pertain to linearity along another axis (like position or time), not the amplitude scaling with defect size.