An ammeter has a 50 Ω internal resistance and 1 mA full-scale movement. For a 10 mA range, what is the approximate shunt resistance RSH1___________?
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Answer: B. 5.5 Ω
Explanation
Extending an ammeter measurement range requires placing a parallel shunt resistor across the movement. Calculation using the fifty ohm internal resistance and current values yields approximately five point five ohms. This shunt diverts excess current around the sensitive galvanometer movement during measurements. Galvanometer movements feature low full scale current ratings requiring external shunt resistors for high ranges. Parallel resistor formulas ensure the correct fraction of total current passes through the meter movement. Ammeter shunts must handle high currents without overheating or changing resistance value.
Multimeter design relies on precision shunt resistors to provide multiple selectable current measurement ranges. Technicians use shunts to measure large industrial currents safely using standard panel meters. Calculating correct shunt resistance prevents accidental burnout of sensitive meter movements. Option A provides an incorrect calculation result that does not match the shunt formula outcome. Option C represents the internal meter resistance rather than the required parallel shunt. Option D gives a different numerical value that fails to satisfy the ammeter range extension formula.
- Subject
- Engineering
- Category
- Electrical Engineering
- Topic
- —
- Difficulty
- medium
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