Question

1. Two resistors (R1 & R2) when connected in series have an equivalent resistance of 9 Ohms, and when they are connected in parallel, have an equivalent resistance of 2 ohms. Calculate the individual values R1 and R2.                                                                                                                
2. The resistance of a wire is 60 Ω. Find the resistance of another wire, having double the length, three time the area and half the resistivity of the first one.                                                           
3. Given resistors 2 Ω, 4 Ω and 6Ω, design the combination to provide an equivalent resistance of 3 Ω.                                                                                                                                                     

Answer 1

This is the only case in which Req is 3 ohm .

In other case when 2 ohm is in series with 6 ohm and then this combination is in parallel with 4 ohm have Req=32/12 = 2.67ohm. ( Wrong Case)