Question

By using only two resistance coils singly, in series or in parallel one should be able to obtain resistances of $3$ , $4$ , $12$ and $16 \, \Omega$ . The separate resistances of the coil are

• A. $3$ and $4$
• B. $4$ and $12$
• C. $12$ and $16$
• D. $16$ and $3$

Answer 1

Answer: (B)

If we take $R _{1}=4\Omega$ , $\text{R}_{2}=12\Omega$ then in series resistance
$\text{R} = \text{R}_{1} + \text{R}_{2}$
$ = 4 + 1 2$
$=16\Omega$
In parallel, resistance $R =\frac{4 \times 12}{4 + 12}=3\Omega$
$\text{So}R _{1}=4\Omega$ , $R_{2} =12\Omega$