Which of the four statements true?a. An ideal emf device sets up a potential difference and a real emf device does not. b. A real emf device sets up a potential difference and an ideal emf device does not. c. An ideal emf device has internal resistance and a real emf device does not. d. A real emf device has internal resistance and an ideal emf device does not.

The true statement among the options is;

d. A real emf device has internal resistance and an ideal emf device does not.

Explanation:

The internal resistance of an ideal emf device is zero to which allows the perfect movement of charges between terminals. This results in the emf of an ideal emf device being equal to the potential difference across the terminals of the device

By definition, an ideal emf device is an emf device with zero internal resistance

There is some level of resistance in a real emf device and the emf of the device is equal to the potential difference across its terminals only if there is no current flowing through it.

some think that theories become laws, but theories and laws have separate and distinct roles in the scientific method. a law is a description of an observed phenomenon in the natural world that hold true every time it is tested. it doesn't explain why something is true; it just states that it is true.

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