Which term describes materials whose properties can be altered when subjected to external stimuli?

• A. Smart material
• B. Adaptive material
• C. Responsive material
• D. Modulated material

Answer: (A)

Materials that can change their properties in response to external stimuli are known as smart materials. This means their behavior—such as shape, stiffness, color, or electrical properties—can be altered by cues like temperature, electric or magnetic fields, light, or mechanical stress. That responsive capability lets them act as actuators, sensors, or adaptable components in devices. Examples include shape memory alloys that return to a programmed shape when heated, piezoelectric materials that deform under an electric field, and electrochromic materials that change color with voltage. While terms like adaptive or responsive are sometimes used descriptively, smart materials is the established, broad category that captures the idea of property changes driven by external stimuli, making it the best fit for this description.