Two resistors with resistances 5Ω and 15Ω are to be connected to a battery of emf 9V so as to obtain:

(i) minimum current

(ii) maximum current.

(a) Show with the help of a diagram how you would connect the resistances in each case.

(b) Calculate the strength of the total current in the circuit in each of the two cases.

(a)

- For minimum current flow: In order to obtain the minimum current flowing through the circuit, the resistors must be connected in series with each other.
- For maximum current flow: In order to obtain the maximum current flowing through the circuit, the resistors must be connected in parallel with each other.

(b)

- For minimum current flow: Two resistors of resistances R1 and R2 are connected in series as:

The equivalent resistance of the circuit is given as:

R = R1 + R2 = 5 + 15 = 20Ω

According to Ohm’s Law:

V = IR

Where,

V = emf of the battery = 9V

I = Total current flowing through the circuit

- For maximum current flow: Two resistors of resistances R1 and R2 are connected in parallel as:

The equivalent resistance of the circuit is given as:

According to Ohm’s law

V = IR

V = emf of the battery =9v

I = Total current flowing through the circuit