If the characteristic frequency (fg) of a material is 125 Hz, the test frequency required for a f/fg ratio of 10 is:

To determine the test frequency needed for a f/fg ratio of 10, we start with the given characteristic frequency (fg) of 125 Hz. The f/fg ratio indicates that the test frequency (f) must be 10 times the characteristic frequency.

Calculating the test frequency involves multiplying the characteristic frequency by the ratio:

f = fg × (f/fg ratio)

f = 125 Hz × 10

f = 1250 Hz

Since 1250 Hz is equivalent to 1.25 kHz, this confirms that the correct answer is indeed the option indicating a frequency of 1.25 kHz. Understanding this calculation is crucial, as the characteristic frequency is a key parameter in Eddy Current Testing, influencing the choice of test frequency to achieve accurate and effective inspections.