Question

we have three resistance of value to 2ohm 3 ohm and 6 ohm which of the following combination will give an effective resistance of 4 Ohm?​

Answer 1

First 6 ohm and 3 ohm are in parallel so there effective resistance is 2 ohm.

and now this effective resistance (2 ohm) is in series with another 2 ohm resistance.

so effective resistance 2 + 2 = 4 ohm.

Answer 2

Answer:

We are asked to find the correct combination of resistors which will give the output as 4 ohm. For this, we'll use the parallel and series combination of resistors.

Explanation:

Parallel Combination of resistors: In the parallel combination of resistors, resistors are arranged parallel to each other. In this combination, current is distributed in each branch of wire containing resistors.

If two resistors, R₁ and R₂ are arranged in parallel, their resultant R' would be:            

                                     1/R' = 1/R₁ + 1/R₂

Series Combination of Resistors: In the series combination, resistors are arranged in series or linearly to each other. In this, voltage is distributed across each resistor.

Resistance of two wires R₁ and R₂ in series with each other:

                                     R' = R₁ + R₂

Now, proceeding towards the question, we are asked to suggest a combination which will give the desired resistance as output.

Given: Three resistances, R₁ = 2Ω, R₂ = 3Ω and R₃ = 6Ω

To find: Combination of resistances which will give output as 4Ω.

Hence, the possible combination of the three resistances would be:

→ Connecting 3Ω and 6Ω in parallel and then connecting the resultant in series with 2Ω.

For R₂ and R₃ to be in parallel, we'll get:

1/R' = 1/3 + 1/6

1/R' = 1/2

R' = 2Ω

Now, connecting R' and R₁ in series,

R'' = 2 + 2

R'' = 4Ω

Hence, the given combination gives the desired output. Therefore, it is correct.