Electrical Engineering XYZ MCQs
A working diode must have:
- High resistance when forward biased, while low resistance when reverse bias
- Low resistance when forward or reverse biased
- High resistance when forward or reverse biased
- Low resistance when forward biased, while high resistance when reverse bias
Correct answer: 4. Low resistance when forward biased, while high resistance when reverse bias
Explanation:
- Forward Bias: When a diode is forward biased (i.e., a positive voltage is applied to the anode and a negative voltage to the cathode), it allows current to flow easily. In this state, the diode exhibits low resistance. This is because the positive voltage applied to the anode repels the holes in the P-type material and attracts the electrons in the N-type material, facilitating the flow of current across the junction.
- Reverse Bias: When a diode is reverse biased (i.e., a positive voltage is applied to the cathode and a negative voltage to the anode), it blocks the flow of current. In this state, the diode exhibits high resistance. This is because the positive voltage applied to the cathode repels the electrons in the N-type material and attracts the holes in the P-type material, creating a depletion region with a high electric field that prevents the flow of current.
So, the correct option is: Low resistance when forward biased, while high resistance when reverse biased.