Electronic Devices

In a digital multimeter, a diode is used to control the direction of current flow. Diodes allow current to pass in only one direction (forward bias) and block it in the opposite direction (reverse bias). This property is essential for:
Testing diodes and checking their polarity.
Protecting the meter from reverse polarity damage.
Rectifying AC signals in measurement circuits. The diode test function in a multimeter sends a small voltage through the diode and measures the voltage drop, typically 0.6V to 0.7V for silicon diodes in forward direction. Explanation of other options:
(A) To measure frequency – Done by the frequency function, not diode.
(B) To store electrical charge – This is the function of a capacitor.
(D) To measure amount of AC voltage – Done by the AC voltage function.