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Obtain an expression for the effective resistance in the combination of two resistors R1 and R2 in parallel. Sketch the combination also |
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Answer» we have to obtain an expression for the EFFECTIVE resistance in the COMBINATION of two resistors R₁ and R₂ in parallel. have to skatch the combination also. solution : see diagram, here two resistors of RESISTANCES R₁ and R₂ are joined in parallel with a circuit of emf V. let i₁ is current passing through the resistor R₁ and i₂ is current passing through the resistor R₂. we know, if resistors are joined in parallel combination, potential difference across each resistors MUST be same. so, V = i₁R₁ and V = i₂R₂ [ from Ohm's LAW ] let effective resistance is Req then V = iReq here i = i₁ + i₂ ⇒V/Req = V/R₁ + V/R₂ ⇒1/Req = 1/R₁ + 1/R₂, This is required expression. Therefore effective resistance of two resistors R₁ and R₂ joined in parallel, is given by, 1/Req = 1/R₁ + 1/R₂ |
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