Physics · Internal resistance, potential difference and emf of a cell, a combination of cells in series and parallel

Which of the following devices has a source of emf inside it?

Which of the following devices has a source of emf inside it?

  • A. Voltmeter
  • B. Ammeter
  • C. ohm-meter
  • D. Rectifier

Step-by-step solution

An ohm-meter measures resistance by applying a known voltage (from an internal battery, which is a source of emf) to the unknown resistor and measuring the resulting current. The other devices (voltmeter, ammeter, rectifier) typically do not have an internal source of emf.
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