Machine-translated by Google. Questions are authored in English.
Top

Discussion

Following Wheatstone bridge is balance when \(P_{AB} = 500\ \Omega\), \(Q_{BC} = 250\ \Omega\) and \(S_{AD} = 12\ \Omega\). Determine \(R_{DC}\).

A Wheatstone bridge with resistors P between A and B, Q between B and C, an adjustable S between A and D and R between D and C, a galvanometer between B and D and a battery across A and C

  • A.6 Ω
  • B.12 Ω
  • C.24 Ω
  • D.48 Ω

Answer: A

R_DC is 6 Ω. A Wheatstone bridge is balanced when the ratio of the resistances in one arm equals the ratio in the other, so the products of opposite arms are equal. With P in AB and Q in BC, S in AD and R in DC:

\[ \frac{P_{AB}}{Q_{BC}} = \frac{S_{AD}}{R_{DC}} \]

\[ \frac{500}{250} = \frac{12}{R_{DC}} \]

\[ R_{DC} = 6\ \Omega \]

The value 24 Ω is what one gets by taking the ratio the wrong way round, and 12 Ω and 48 Ω do not satisfy the balance condition. The first option is correct.

No comment is present. Be the first to comment.
Loading…

Post your comment

Please log in or register to post a comment.