Question

The equivalent resistance of network of three 2 ohm resistors
can not be :
a) 0.67 ohm (b) 2 ohm (c) 3 ohm(d) 6 ohm

Answer 1

Answer:

a

Explanation:

Answer 2

Answer:

The correct answer is option(b)

(b) 2 ohm

Explanation:

Given: Three 2 ohm resistors.

• 2ohm cannot be obtained if the equivalent resistance of network of 2 ohm resistors.
• The resultant resistance cannot be equal to the individual resistance if we arranged the three set of resistors either in series or parallel.

1. If the 3 resistors are arranged in parallel we get 0.67 ohms.
2. If the 3 resistors are arranged in series we get 6 ohms.
3. If 2 resistors are arranged in parallel and the third resistor is in series we get 3 ohm.

Solution:

1) 3 resistors in parallel :

$(\frac{1}{2} + \frac{1}{2} +\frac{1}{2}) = \frac{3}{2} = \frac{2}{3}$

= 0.67 ohms

2) 3 resistors in series = 2 + 2 + 2 = 6 ohms

3) 2 resistor in parallel and one in series

$(\frac{1}{2} + \frac{1}{2}) = \frac{2}{2} = 1\\ 1 + 2 = 3$

= 3 ohms

Note:

• For resistors in series add the resistance.
• For resistors in parallel take reciprocal of the resistance add and then take the reciprocal for the answer.

Answer : option(b)

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