What does the screen of a DMM display when the red and black meter leads are reversed in a DC Voltage measurement?

When measuring DC voltage with a digital multimeter (DMM), the orientation of the meter leads is critical. If the red lead, typically connected to the positive terminal, is reversed and connected to the negative terminal, while the black lead (usually the negative side) connects to the positive terminal, the DMM will display the measured voltage but with a negative sign.

This is because voltage is defined as the potential difference between two points, and reversing the leads effectively inverts the reference point. The meter senses this as a negative voltage because it measures the difference in potential starting from the lead connected to the black probe to the lead connected to the red probe. Therefore, the correct response reflects that the voltage is displayed with a negative sign, indicating that the polarity has been reversed.

The other possible answers reflect different scenarios that are not applicable when leads are reversed. For instance, having no display would typically suggest a circuit open or a malfunction, which would not occur merely from reversing the leads; it would still provide a measurement, albeit with a negative sign.