An x - ray tube used for cancer therapy operates at4.0 MV, with a beam current of 25 mA striking the metal target.Nearly all the power in the beam is transferred to a streamof water flowing through holes drilled in the target. What rateof flow, in kilograms per second, is needed if the rise in temperature(ΔT ) of the water is not to exceed 50.°C?

A light bulb, rated 12V drew 0.5A when it reached a temperature of 40 degrees Celsius. It was switched on at a temperature of 25 degree Celsius. What was the current drawn by the lamp at the moment of switching? (Consider the filament as Tungsten with a temp. coefficient of 0.0051 @ 25 degree Celsius). The total length of the filament is 12 inches and cross-sectional area is 100 CM.

In proton beam therapy, a beam of high-energy protons is used to kill cancerous cells in a tumor. In one system, the beam, which consists of protons with an energy of 2.8×10−11J2.8×10−11J, has a current of 76 nAnA. The protons in the beam mostly come to rest within the tumor. The radiologist has ordered a total dose corresponding to 3.4×10−3J3.4×10−3J of energy to be deposited in the tumor. A)How many protons strike the tumor each second? B)How long should the beam be on in order to deliver the required dose?

A steady 4.46-mA current is present in a wire of diameter 1.0 mm. Calculate the drift velocity of the electrons, in nanometers per second, knowing that the concentration of free electrons is 1.87 x 1028 electrons per cubic meter. The charge of the electron is 1.60 x 10-19C.