Question

Two resistors, with resistances 5 Ω and 10 Ω respectively are to be connected to a battery of emf 6 V so as to obtain: (i) minimum current flowing (ii) maximum current flowing (a) How will you connect the resistances in each case? (b) Calculate the strength of the total current in the circuit in the two cases.

Answer 1

 (a) (i) For minimum current flowing In order to obtain the minimum current flowing through the circuit, the resistors must be connected in series with each other. (ii) For maximum current flowing In order to obtain the maximum current flowing through the circuit, the resistors must be connected in parallel with each other.

(b) (i) For minimum current flowing Two resistors of resistances R1 and R2 are connected in series, as shown: Equivalent resistance of the circuit is given as: R = R1 + R2 = 5 + 10 = 15 Ω According to Ohm’s law: V = IR Where, V = emf of the battery = 6 V I = Total current flowing through the circuit (ii) For maximum current flowing Two resistors of resistances R1 and R2 are connected in parallel, as shown: Equivalent resistance of the circuit is given as: According to Ohm’s law: V = IR Where, V = emf of the battery = 6 V I = Total current flowing through the circuit

Answer 2

Answer:

(a) (i) For minimum current we must make R maximum. This can be done by connecting the resistances in series.

(ii) For maximum current we must make R minimum. This can be done by connecting the resistances in parallel.