How is the fuse wire connected to a circuit ? In series / parallel ?

Two heater wires of equal length are first connected in series and then in parallel. The ratio of heat produced in two cases is

In an electrical circuit resistances can be connected In series or parallel or combination or both:- If R_1 and R_2 are two resistors connected in series whatistheir effective resistance.

In an electrical circuit resistances can be connected in series or parallel or combination of both.If R_1 and R_2 are two resistors connected in series what is their effective resistance.

In an electrical circuit resistances can be connected in series or parallel or combination of both.What is the effective resistance of the given figure