Question

A 9.0 volt battery is connected to four resistors in a parallel circuit. The resistors have 7.0 Ω, 5.0 Ω, 4.0 Ω, and 2.0 Ω respectively. What is the total current in the circuit?

Answer 1

Series,effective resistance =R₁+R₂+R₃...
parallel,effective resistance 1/R=1/R₁ +1/R₂ +1/R₃...
 
Here,effective resistance 1/R =1/7 +1/5+ 1/4+1/2  
                                           =1.092
                                       R = 1/1.092 =0.915Ω
voltage V=9 V 
current I=V/R
           I=9 / 0.915
            =9.83 A

Answer 2

Parallel resistance = <u />$\frac{1}{7}$ + $\frac{1}{5}$ + $\frac{1}{4}$ + $\frac{1}{2}$
=$\frac{140}{153}$

now , V= 9V
V = IR
I = $\frac{V}{R}$
I = $\frac{9}{140}$ x 153
I = 9.835714 A