Final answer:
The new exposure time needed to produce the same diagnostic radiograph when increasing the current from 5 mA to 15 mA is 0.10 seconds, calculated using the principle that the product of current and time remains constant for a given level of film exposure.
Step-by-step explanation:
The question pertains to the principles of radiography, specifically the calculation of exposure time required for producing a diagnostic radiograph when varying the milliampere (mA) settings on the X-ray machine. When the current is increased, the exposure time can be decreased proportionally to maintain the same level of film exposure.
To calculate the new exposure time when the mA is increased from 5 mA to 15 mA (a threefold increase), we apply the concept that the product of current (mA) and exposure time (s) should remain constant to achieve the given level of film exposure. Therefore, if we start with an original exposure of 5 mA at 0.30 seconds, to find the new exposure time required at 15 mA, we set up the equation:
Original mA × Original time = New mA × New time
(5 mA) × (0.30 s) = (15 mA) × (New time)
New time = (5 mA × 0.30 s) / 15 mA
New time = 0.10 seconds