Exams › JEE Main › Physics

An ammeter has a full-scale reading of 1 A and an internal resistance of 0.81 Ω. What shunt resistance must be connected to extend its measuring range to 10 A?

1. 0.03 Ω
2. 0.3 Ω
3. 0.9 Ω
4. 0.09 Ω

Correct answer: 0.09 Ω

Solution

To extend the ammeter's range to 10 A, a shunt resistor is needed to bypass most of the current. The correct shunt resistance can be calculated using the formula for shunt resistors, which shows that a lower resistance allows more current to pass through the shunt while keeping the ammeter within its safe operating range.

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 →