Question 161Electricity & Electronics - QMED

The correct answer is D) 'ghost' voltages due to electromagnetic energy in the air. When a digital multimeter is set to measure AC voltage and its leads are disconnected, it may still display a small non-zero reading. This is due to the presence of stray electromagnetic fields in the environment, which can induce small amounts of voltage in the meter's circuitry. This phenomenon is known as 'ghost' or 'phantom' voltages, and it is a common occurrence with sensitive electronic measurement devices. The other options are incorrect because they do not accurately explain the cause of the non-zero reading in this scenario. A poor ground for the meter case (A) would not affect the AC voltage reading, and capacitors inside the meter (B) would not create a continuous 'ghost' voltage. Miscalibration of the meter (C) would result in a consistent offset, not a fluctuating reading.