What is the lowest range that will show on the IM-270/PD dosimeter?

• A. 1
• B. 2
• C. 4
• D. 10

Answer: (C)

The IM-270/PD pocket dosimeter is designed with discrete measurement ranges, and the readout can only resolve signals above a certain level. The device’s circuitry and ionization chamber provide a readable signal reliably starting around 4 milliroentgens (mR). Below that, the signal isn’t distinguishable from noise or background, so the display cannot show smaller values like 1 or 2. Therefore, the first readable range on this dosimeter is 4 mR, with higher ranges (like 10 mR) used for larger exposures. In short, very low doses won’t produce a distinct reading on this instrument; if you expect readings under 4 mR, you’d need a more sensitive dosimeter or longer integration.