Bennett Mechanical Comprehension Practice Test 2025 - Free Practice Questions and Review Guide

A bimetallic strip functions in thermostats by bending in response to temperature changes. This strip is typically made of two different metals that expand at different rates when heated. As the temperature increases, one metal expands more than the other, causing the strip to bend. This bending action is crucial because it activates the thermostat's switch, which can then either turn on or off a heating or cooling system.

The unique property of the bimetallic strip allows it to act as a mechanical temperature sensor, providing a simple yet effective method for regulating temperature in various devices. The other choices involve processes that do not accurately describe the behavior of the bimetallic strip in this context. For instance, contraction doesn't occur in the same manner as the bending reaction to heat, generating electricity is not a characteristic function of a bimetallic strip, and automatic cooling is not a direct outcome of the strip's operation. Understanding the bending mechanism is essential for grasping how thermostats maintain desired temperatures effectively.