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^−11 J, has a current of 80 nA. The protons in the beam mostly come to rest within the tumor. The radiologist has ordered a total dose corresponding to 3.4×10^−3 J of energy to be deposited in the tumor. a) How many protons strike the tumor each second? Enter your answer as a number of protons. b) How long should the beam be on in order to deliver the required dose?

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^−11 J, has a current of 80 nA. The protons in the beam mostly come to rest within the tumor. The radiologist has ordered a total dose corresponding to 3.4×10^−3 J of energy to be deposited in the tumor. a) How many protons strike the tumor each second? Enter your answer as a number of protons. b) How long should the beam be on in order to deliver the required dose?