Question

What is the effective resistance between the points A and D? A) 1.3 Ω B) 2.2 Ω C) 10 Ω D) 12 Ω

Answer 1

B) 2.2 Ω

Step-by-step explanation:

First of all, we should notice that the resistor placed between A and B is short-circuited. In fact, the current from point A will follow the wire above between A and C (which has zero resistance), so we can basically ignore the presence of the resistor between A and B, since it has no effect on the circuit.

Then, we can notice that the two resistors between CB and CD are in parallel to each other; therefore, their equivalent resistance is given by:

`(1)/(R)=(1)/(R_(BC))+(1)/(R_(CD))=(1)/(4.0 \Omega)+(1)/(5.0 \Omega)=(9)/(20 \Omega)\\R= (20 \Omega)/(9)=2.2 \Omega`