What is one effect of using a wetting agent in immersion testing?

Using a wetting agent in immersion testing is primarily aimed at improving sound transmission. Wetting agents reduce the surface tension of the water, allowing for better contact between the testing medium (water with the wetting agent) and the material being tested. This improved contact enhances the propagation of ultrasonic waves through the medium, leading to more accurate and reliable test results.

When sound waves pass from the transducer into the test material, efficient sound transmission is crucial for detecting defects and imperfections. By ensuring that the ultrasonic waves effectively penetrate the material without significant loss of energy, the wetting agent plays a vital role in ensuring the test's effectiveness.

The other options focus on different aspects and functionalities that are not directly tied to the purpose of a wetting agent in immersion testing, making them less relevant in this context.