Question

③ Three resistors of 3ohm , 4ohm , and 5ohm are
connected in series. Find the equivalent
resistance.​

Answer 1

Answer:

Left side figure shows the circuit that has parallel combination of 6Ω, 4Ω and 3Ω resistors connected in series to a 1Ω resistor.

This resistor combination is connected to a cell of emf 2V and internal resistance 1Ω.

 

Equivalenet resistance of 6Ω, 4Ω and 3Ω resistors =  (6×4×3)/ [ 6×4 + 4×3 + 3×6 ] = 4/3 Ω .

 

Replacement of parallel combination with 4/3 Ω is shown in right side figure.

 

Current in the circuit = 2V / [ (4/3)+1+1 ] Ω = 0.6 A

 

current through 1 Ω resistor = 0.6 A

 

Potential difference across the parallel resitors = current × equivalent Resistance = 0.6A × (4/3) Ω = 0.8 V

 

Hence current through 6Ω resistor = 0.8V/6Ω = 0.133 A

 

current through 4Ω resistor = 0.8V/4Ω = 0.2 A

 

current through 3Ω resistor = 0.8V/3Ω = 0.266 A

Explanation:

Answer 2

Explanation:

$\\ here \: R_{1} =3Ω \: \: R_{2} = 4Ω \: \: R_{3} = 5Ω\\ \\ Equivalent \: \: resistance \: R_{eq} =R_{1} + R_{2} + R_{3} \\ \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: = 3Ω+ 4Ω + 5Ω \\ \: \: \: \: = 12Ω$