Texas Industrial Radiography Gamma Practice Test

If the range switch on a survey instrument is set at X1 and the needle reads "6," what is the indicated dose rate?

1. 60 mr/hr

2. 6 mr/hr

3. 0.6 mr/hr

4. 600 mr/hr

The correct answer is: 6 mr/hr

In survey instruments, the range switch setting determines the scale of the measurement that the instrument is utilizing to display the radiation dose rate. When the range switch is set to a specific position, such as X1, it typically indicates a multiplier for the reading shown on the scale. In this case, if the needle is reading "6" while the range switch is at the X1 setting, the interpretation is that the measurement directly corresponds to the dose rate without any multiplication factor. Therefore, the indicated dose rate is simply taken as 6 milliroentgen per hour (mr/hr). This understanding is crucial as it allows radiographers and operators to accurately interpret the readings from the instrument to ensure safety and compliance with radiation exposure guidelines.