Question

For the circuit shown in the diagram, calculate
(I) the resultant resistance
(II) the total current
(III) the voltage across 7 ohm resistor

Answer 1

refer to the attachment...
total resistance is 31/3 ohm
current is 18/31 A
voltage across 7 ohm resistance is 6V

Answer 2

Explanation :

From the given figure,

(1) $5\ \Omega$ and $10\ \Omega$ resistors are in parallel. There equivalent is given by :

$\dfrac{1}{R}=\dfrac{1}{R_1}+\dfrac{1}{R_2}$

$R=\dfrac{10}{3}\ \Omega$

$\dfrac{10}{3}\ \Omega$ and $7\ \Omega$ resistors are in series.

So, $R_{eq}=\dfrac{31}{3}\ \Omega$

(2) According to Ohm's law :

$I=\dfrac{V}{R}$

$I=\dfrac{6\ V}{\dfrac{31}{3}\ \Omega}$

$I=\dfrac{18}{31}\ A$

(3) Voltage across $7\ \Omega$ resistor is

$V=\dfrac{18}{31}\ A\times 7\ \Omega$

$V=4.06\ V$

Hence, this is the required solution.