Question

V= 12 v
R1 = 20 ohm
R2 = 15 ohm
R3 = 20 ohm
R4 = 15 ohm
R5 = 8 ohm
find total resistance ​

Answer 1

Given :

5 resistors are connected as shown in fig

• R₁ = 20 Ω
• R₂ = 15 Ω
• R₃ = 20 Ω
• R₄ = 15 Ω
• R${\sf {_5}}$ = 8 Ω

potential difference, V = 12V.

To find :

The total resistance of the circuit

Solution :

First of all we need to simplify the given circuit.

Refer fig -1 in the attachment we can see R₂ and R₄ are connected in series.

➠ R₂₄ = R₂ + R₄

➠ R₂₄ = 15 + 15

➠ R₂₄ = 30Ω

And now, R₂₄ and R₃ come in parallel (as shown in fig-2)

➠ 1/R₂₄₃ = 1/R₂₄ + 1/R₃

➠ 1/R₂₄₃ = 1/30 + 1/20

➠ 1/R₂₄₃ = 2+3/60

➠ 1/R₂₄₃ = 5/60

➠ 1/R₂₄₃ = 12Ω

finally R₁, R₂₄₃ and R${\sf {_5}}$ comes in series (as shown in fig-3)

➠ R = R₁ + R₂₄₃ + R${\sf {_5}}$

➠ R = 20 + 12 + 8

➠ R = 40Ω

thus, total resistance of the circuit is 40Ω

Remember !

SI unit of resistance is Omega or ohm (Ω)