Tentang Olimpiade Fisika (Pdf) - Yohanes Surya.com

Figure II-2. The equivalent closed circuitsystem involving the sensing predator, the prey and the surrounding seawater.In the figure, V is the voltage difference between the detector’s spheres due to theelectric field induced by the prey, R m is the inner resistance due to thesurrounding sea water. Further, V d and R d are respectively the voltage differencebetween the detecting spheres and the resistance of the detecting element withinthe predator.Questions:1. Determine the current density vector (current per unit area) caused bya point current source I s at a distance r in an infinite medium. [1.5 pts]2. Based on the law , determine the electric field strength at themiddle of the detecting spheres (at point P) for a given current I s thatflows between two spheres in the prey’s body [2.0 pts].3. Determine for the same current I s , the voltage difference between thesource spheres (V s ) in the prey [1.5 pts]. Determine the resistancebetween the two source spheres (R s ) [0.5 pts] and the power produced bythe source (P s ) [0.5 pts].4. Determine R m [0.5 pts], V d [1.0 pts] in Figure II-2 and calculate also thepower transferred from the source to the detector (P d ) [0.5 pts].5. Determine the optimum value of R d leading to maximum detected power[1.5 pts] and determine also the maximum power [0.5 pts].23