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The net resistance of two resistors R1 and R2 connected in series is 8 ohm and their net resistance in parallel is 2ohm. What are the values of indivi
Question

The net resistance of two resistors R1 and R2 connected in series is 8 ohm and their net resistance in parallel is 2ohm. What are the values of individual resistances R1 and R2, respectively?

A.

8 ohm;0 ohm

B.

4 ohm;4 ohm

C.

6 ohm;2 ohm

D.

2 ohm;6 ohm

Correct option is B

The correct answer is (b) 4 ohm; 4 ohm.
Explanation:
· Given: Rseries =R1+R2=8=R₁ + R₂ = 8​ ohm Rparallel = =(R1×R2)(R1+R2)=2=\frac{(R₁ × R₂)}{(R₁ + R₂)} = 2​ ohm
· Substituting R1+R2=8 R₁ + R₂ = 8 ohm into the parallel resistance formula: (R1×R2)8=2R1×R2=16\frac{(R₁ × R₂)}{8} = 2 → R₁ × R₂ = 16
· Solving the quadratic equation x28x+16=0x² - 8x + 16 = 0 : x=4x = 4​ and x=4x = 4
· Therefore,R1=4 R₁ = 4​ ohm and R2=4R₂ = 4​ ohm.
Information Booster
· Series combination: Total resistance is the sum of all resistances: Rtotal =R1+R2+= R₁ + R₂ + …
· Parallel combination: Total resistance is given by: Rtotal =1(1R1+1R2+)= \frac{1}{(\frac{1}{R₁} + \frac{1}{R₂ +} …)} 
· For series: Rseries=R1+R2 = R₁ + R₂
· For parallel: Rparallel=(R1×R2)(R1+R2) = \frac{(R₁ × R₂)}{(R₁ + R₂)}
 Applications:

  • Series connections are used for uniform current flow in circuits.
  • Parallel connections are used in household wiring to ensure constant voltage.
  •  Practical example: Designing resistive circuits in electronic devices like TVs and radios.

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