D.C. Circuits Parallel Resistance
Here’s an “ingelious” way to understand why the effective resistance for parallel circuits in JC A Level H2 Physics D.C. Circuits. is always smaller than the resistor with the smallest resistance.
Consider a fast food restaurant with only 1 fast counter available to serve. It is efficient, but the queue is simply too long. This is analogous to the path connected to the 1Ω resistor.
Assuming there is another slow counter (100Ω resistor) that is open to serve customers. Although it is a lot less efficient, it will still help to reduce the customers’ waiting time. Hence the overall waiting time will be lesser than having a fast counter alone. Therefore, the effective resistance of the parallel circuit must be lesser than 1Ω.