Question

A student has two resistors- 2 Ω and 3 Ω. She has to put one of them in place

of R2 as shown in the circuit. The current that she needs in the entire circuit is

exactly 9A. Show by calculation which of the two resistors she should choose​

Answer 1

Explanation:

The overall current needed = 9A. The voltage is 12V Hence by Ohm’s Law V=IR, The resistance for the entire circuit = 129129 = 43Ω43Ω = R R1 and R2 are in parallel

Hence, R=(R1R2)(R1+R2)(R1R2)(R1+R2)= 4R2(4+R2)4R2(4+R2)= 4343 R2 = 2Ω

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Answer 2

Answer:

Explanation:

The overall current needed = 9A.

The voltage is 12V  

Hence by Ohm’s Law V=IR,

The resistance for the entire circuit = 12/9= 4/3Ω = R  

R1 and R2 are in parallel.

Hence, R=(R1R2)/(R1+R2)= 4$R^{2}$/(4+R2)= 4/3

$R_{2}$= 2Ω