The gamma photons created during a pet scan are detected when they encounter a scintillator and produce a burst of light. this light is then turned into an electrical signal when it strikes a metal and an electron is emitted by means of the photoelectric effect. while this is not practical for actual medical applications, assume that the metal used in the detector is silver, with a work function of 4.7ev. planck's constant is 4.14×10−15ev⋅s. a) what is the minimum frequency light must have to eject an electron from the surface? a. 1.1×10^12 hzb. 1.2×10^19 hzc. 2.3×10^15 hzd. 1.1×10^15 hz

In the future, people will only enjoy one sport: electrodisc. in this sport, you gain points when you cause metallic discs hovering on a field to exchange charge. you are an electrodisc player playing the popular four disc variant. the disks have charges of qa = −8.0 µc, qb = −2.0 µc, qc = +5.0 µc, and qd = +12.0 µc. (1) you bring two disks together and then separate them. you measure the resulting charge of these two disks and find that it is +5.0 µc per disk. which two disks did you bring together? (a) a and b (b) a and c (c)a and d (d)b and c(e) b and d (f) c and d. (2) you bring three disks together and then separate them. you measure the resulting charge of these three disks and find that it is +3.0 µc per disk. which three disks did you bring together? a, b, and c (a) a, b, and d (c) a, c, and d (d) b, c, and d. (3) given the resulting charge of each disk measured in (b) is +3.0 µc, how many electrons would you need to add to a disk of this charge to electrically neutralize it? electrons