Apython can detect thermal radiation from objects that differ in temperature from their environment as long as the received intensity of thermal radiation is greater than 0.60 w/m2 . your body emits a good deal of thermal radiation. assume that your body has a surface area of 1.6 m2 , a surface temperature of 30°c, and an emissivity e = 0.97 at infrared wavelengths. as we’ve seen, the intensity of a source of radiation decreases with the distance from the source. if you are outside on a cool, dark night, what is the maximum distance from which a python could detect your presence?

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