Two resistors R1 and R2 are connected in parallel, R2 being greater than R1. The combined resistance is

  • A less than R1
  • B greater than R2
  • C the sum of R1 and R2
  • D the difference of R2 and R1
  • E greater than R1 but less than R2
jamb 1978physics

The correct answer is A. less than R1

When two resistors, \(R_1\) and \(R_2\), are connected in parallel, the combined resistance, \(R_{\text{combined}}\), is given by the formula:

\(\frac{1}{R_{\text{combined}}} = \frac{1}{R_1} + \frac{1}{R_2}\)

Given that \(R_2 > R_1\), it's clear that the combined resistance will be less than the smaller resistor (\(R_1\)) because adding any positive quantity to \(\frac{1}{R_1}\) will yield a result that has a higher denominator than \(R_1\) alone, thus making \(R_{\text{combined}}\) smaller than \(R_1\).

Therefore, the correct answer is less than \(R_1\)

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