Final answer:
The exposure rate at the input phosphor is correctly measured in millirads/second, a unit of radiation intensity, not candelas or lumens, which relate to light intensity and flux.
Step-by-step explanation:
The question pertains to the exposure rate at the input phosphor which is typically measured in units of radiation intensity. The common unit of radiation intensity used for such measurements is the Curie (Ci), which corresponds to a certain number of disintegrations per second.
However, in the options provided, the correct unit for measuring exposure rate in this context is millirads/second because the other units mentioned (candelas or cd, and lumens) relate to luminous intensity and luminous flux respectively, rather than radiation intensity.
The exposure rate as measured at the input phosphor is measured in millirads/second, which is a unit relating to the radiation absorbed by a surface per unit time.
This is different from lumens, which measures the total quantity of visible light emitted by a source, or candelas, which is a unit of luminous intensity in a given direction.
The exposure rate as measured at the input phosphor is in millirads/second.
Exposure rate is a measure of the amount of radiation received per unit of time. In this case, it is measured in millirads (a unit of absorbed dose) per second. This measurement is commonly used in the field of radiology or when evaluating the safety of radiation exposure.