Exams › JEE Main › Physics

In a post office box (a form of Wheatstone bridge) used to measure an unknown resistance, between which pair of terminals should the unknown resistance be connected?

1. B and C
2. C and D
3. A and D
4. B1 and C1

Correct answer: C and D

Solution

In the standard post office box layout, the unknown resistance is connected in the arm between terminals C and D (the gap reserved for X opposite the rheostat arm).

Related JEE Main Physics questions

• A physical quantity X is defined as ε0L(ΔV/Δt), where ε0 denotes the permittivity of free space, L is a length, ΔV is a potential difference, and Δt is a time interval. The dimensional formula of X matches that of which of the following?
• A set of n identical resistors is arranged once in a series combination and once in a parallel combination. What is the ratio of the larger equivalent resistance to the smaller equivalent resistance?
• A resistance coil is connected to a battery. In which arrangement will the maximum heat be produced?
• A bulb is rated at 220 V and 100 W. If the applied voltage falls by 2.5% from its rated value, by what percentage of the rated power will the power output decrease?
• An ammeter has a coil resistance of R. To extend its measuring range by a factor of n, the shunt resistance needed should be:
• How does the drift velocity Vd depend on the strength of the applied electric field?

⚔️ Practice JEE Main Physics free + battle 1v1 →