Question

a circuit contains two devices that are connected in parallel. if the resistance of one of these devices is 12 ohms and the resistance of the other device is 4 ohms, the total resistance of the two devices is a. 0.333 ohms. b. 16 ohms. c. 0.0625 ohms. d. 3 ohms.

Answer 1

R= 1/(1/12+1/4) = 3 ohms

Answer 2

Formula

Resistance for parallel circuit.

`(1)/(R_(Total)) = (1)/(R_(1)) +(1)/(R_(2))`

As given

A circuit contains two devices that are connected in parallel.

if the resistance of one of these devices is 12 ohms and the resistance of the other device is 4 ohms.

`R_(1) = 12\ ohms`

`R_(2) = 4\ ohms`

Put in the above

`(1)/(R_(Total)) = (1)/(R_(1))+(1)/(R_(2))`

`(1)/(R_(Total)) = (1)/(12)+(1)/(4)`

L.C.M of (12,4)= 12

`(1)/(R_(Total)) = (1 + 3)/(12)`

`(1)/(R_(Total)) = (4)/(12)`

`R_(Total) = (12)/(4)`

`R_(Total) = 3\ ohms`

Therefore the total resistance of the two devices is 3 ohms .

Option (b) is correct .