Question

Section 3: (10 marks) Word Problem

Target response size: text portion approximately 1 - 2 paragraphs (or equivalent) of explanation, plus maths portion showing your work

Four electrical devices are connected to powerpoints wired into the same electrical supply circuit. This is a standard Australian residential building circuit rated at 10 A. The devices have power ratings of 200 W, 740 W, 330 W and 1150 W. Can all four devices be operated at the same time on this circuit? 

Answer 1

We have given the current rating i.e. 10A

We know Voltage rating in Australia = 230V

For 1st Device,

$P=VI$

$I_1 = \dfrac{200}{230} = 0.86A$

Similarly for the other three devices current will be

$I_2 = 3.21A$

$I_3=1.43A$

$I_4=5A$

Total current $= 5+1.43+3.21+0.86 = 10.5A$

Hence this value ids greater than the Rated value i.e. $10A.$

Hence, all four devices cannot be operated at the same time on this circuit.