Four resistors with resistance R1= 2N, R2=3N, R3=6 2, R4 =7 N are available and ready to be used. The mathematician chooses two resistors and connect it in a way that it yield a net resistance of 9 N. He returned the resistors and let the physicist take his turn. Without any knowledge, the physicist used exactly the same resistors that the mathematician used, and his connection yields 2N. As an engineer , determine the two resistors that were used. Who connected it series and who connected it in parallel?

Two resistors of resistance R and connected in series with each other and in parallel with a cell with emf V. What is the current flowing through one of the resistors? Select one: a. V/2R b. V/R c. 2V/R d. 2VR

4-5) Before the advent of ohmmeters (even the analog ones), unknown resistances (Runk) were measured using a Wheatstone bridge. The unknown resistance is placed into the circuit at right as shown. The values of R1 and R2 are extremely well known. The resistance of Rvar is adjusted until the meter Runk. Rvar R1. R2 reads no current in the cross branch. The value of Rvar is then read from a dial. Show that Runk can be found from R1 -Ry Rukn