What is the resultant resistance of 3 Ω and 6 Ω resistances connected in series?

CONCEPT:

• Resistances in series combination: When two or more resistances are connected one after another such that the same current flows through them are called as resistances in series.

• The net resistance/equivalent resistance (R) of resistances in series is given by:
• Equivalent resistance, 

​R = R1 + R2      ...(1)

CALCULATION:

Given that: R₁ = 3 Ω  and R₂ = 6 Ω 

Using equation 1,

⇒ R = 3 + 6 = 9 Ω 

EXTRA POINTS:

• Resistances in parallel combination: When the terminals of two or more resistances are connected at the same two points and the potential difference across them is equal is called resistances in parallel.

• The net resistance/equivalent resistance(R) of resistances in parallel is given by:

\(\frac{1}{R} = \frac{1}{{{R_1}}} + \frac{1}{{{R_2}}}\)

• Equivalent resistance decreases in the case of a parallel combination.
• In series combinations, the current remains constant while in case of parallel combination, the potential difference remains constant.