The correct answer is: A. Displacement.
Fiber optic sensors are used to measure a variety of physical quantities, including displacement, temperature, pressure, and strain. They are based on the principle of light propagation in optical fibers. When light travels through an optical fiber, it is affected by changes in the fiber’s refractive index. These changes can be caused by external factors, such as temperature, pressure, or strain. The changes in the refractive index cause the light to be scattered, and this scattering can be detected by a sensor.
Fiber optic sensors are used in a variety of applications, including industrial process control, medical diagnostics, and environmental monitoring. They are a valuable tool for measuring physical quantities in a variety of environments.
Here is a brief explanation of each option:
- Option B: Power. Fiber optic sensors can be used to measure power, but this is not their primary application. They are more commonly used to measure displacement, temperature, pressure, and strain.
- Option C: Current. Fiber optic sensors can be used to measure current, but this is also not their primary application. They are more commonly used to measure displacement, temperature, pressure, and strain.
- Option D: Resistance. Fiber optic sensors cannot be used to measure resistance. They are based on the principle of light propagation in optical fibers, and resistance is not a property of light.