Question

The equivalent resistance of the following arcuit
diagram is 4.2. calculate the value of n.
www
A.
B
n
MW
un
82​

Answer 1

Answer:

for resistance in parallel

1/4.2=1/(8+4)+1/(5+x)

solve and find x

Answer 2

$when \: two \: \: resistor \: are \: connected \: in \: series \\ \: then \: resultant \: resistance \: is \\ \boxed{R=R1+R2 }\\if \: they \: are \: connected \: in \: parallel \: then \: the \: \\ resultant \: resistance \: is \: \\ \boxed {\frac{1}{R} = \frac{1}{R1} + \frac{1}{R2} }$

then

$a = 5 + x \\ b = 8 + 4 = 12 \\ \frac{1}{4.2} = \frac{1}{5 + x} + \frac{1}{12} \\ \frac{1}{4.2}- \frac{1}{12} = \frac{1}{5 + x} \\ = >\frac{1}{5 + x} = \frac{13}{84} \\ x + 5 = 6.46 \\ x = 6.46 - 5 = 1.46$

hope this solution helps you