A Wheatstone bridge is used to determine the value of unknown resistance X by adjusting the variable…

A Wheatstone bridge is used to determine the value of unknown resistance X by adjusting the variable resistance Y as shown in the figure. For the most precise measurement of X, the resistances P and Q

  1. should be approximately equal and are small
  2. should be very large and unequal
  3. do not play any significant role
  4. should be approximately equal to 2X

Solution

For precise measurement of X, value of X should be close to Y. Therefore, resistances P and Q should be equal.
If P and Q are large the current in the galvanometer will be small, and it will be difficult to find the null point. Therefore, P and Q should be small.

Asked in: NEET 2022 (Phase 1)

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