Question

In the diodes shown in the diagrams, which one is reverse biased?

• A.

  

• B.

  

• C.

  

• D.

  

Hint:

Remember that a diode is reverse biased when the potential at the cathode is higher than the potential at the anode.

Answer 1

The Correct Option is C

A diode is reverse biased when the potential at the cathode (n-side) is higher than the potential at the anode (p-side). 
(1) The potential at the anode is -12V, and the potential at the cathode is -5V. Since -12V<-5V, the diode is forward biased. 
(2) The potential at the anode is 0V, and the potential at the cathode is -10V. Since 0V>-10V, the diode is forward biased. 
(3) The potential at the anode is 0V, and the potential at the cathode is +5V. Since 0V<+5V, the diode is reverse biased. 
(4) The potential at the anode is +5V, and the potential at the cathode is +10V. Since +5V<+10V, the diode is forward biased. Therefore, the diode in option (3) is reverse biased.