Question

three equal resistors when combined in series are equal to 90W. find the equivalent resistance in parallel combination.. pl help

ASAP ​

Answer 1

Answer:

Correction: 3 equal resistors combined in series is equal to 90 ohms.

Effective Resistance in Series Connection = R₁ + R₂ + R₃

⇒ 3 R₁ = 90 ohms  [ Since all the three resistors are equal ]

⇒ R₁ = 90/3 = 30 ohms

Effective Resistance in Parallel Connection = 1/R₁ + 1/R₂ + 1/R₃

⇒ 1/R = 1/R₁ + 1/R₁ + 1/R₁

⇒ 1/R = 3/R₁

⇒ R = R₁/3

⇒ R = 30 / 3 = 10 ohms

Hence the equivalent resistance in parallel connection is 10 ohms.

Hope it helped !!

Answer 2

Answer:

The value of equivalent resistance in a parallel combination is 10 ohms.

Explanation:

Given,

The equivalent resistance(R) of 3 equal resistors (R1) connected in series is 90 ohms.

To find,

The equivalent resistance in parallel combination.

Calculation,

As R = R1 + R1 + R1 (As the resistances in the series are just the sum of resistances)

⇒ R = 3 × R1

⇒ 90 = 3 × R1

⇒ R1 = 30 ohms.

Now with the help of the three R1 = 30-ohm resistances, are connected in parallel, then the equivalent resistance is:

$\frac{1}{R} = \frac{1}{R1} + \frac{1}{R1} + \frac{1}{R1}$

⇒ 1/R = 3/R1

⇒ 1/R = 3/30

⇒ R = 10 ohms.

Therefore, the value of equivalent resistance in a parallel combination is 10 ohms.

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