Electron Devices Surprise Quiz - 1

A silicon PN junction diode is forward-biased and connected in a circuit with a 5V supply and a 1kΩ resistor. What is the approximate current through the diode?

• 0.5 mA

• 4.3 mA

• 5 mA

• 4.7 mA

A PN junction diode is reverse-biased. Which of the following outcomes is most likely if the reverse voltage exceeds the breakdown voltage?

• The diode conducts with zero resistance

• The diode starts conducting large current, possibly damaging itself

• The diode blocks all current flow regardless of voltage

• The diode behaves like a forward-biased diode

You replace a silicon diode in a forward-bias circuit with a germanium diode. What change do you expect in the circuit current?

• No change

• Slight decrease due to higher cut-in voltage

• Increase due to lower forward voltage drop

• Diode stops conducting

You are designing a circuit that allows current to pass only during the negative half cycle of the AC signal. How should you orient the PN diode?

• Anode to positive AC terminal

• Cathode to ground

• Anode to negative AC terminal

• Cathode to negative AC terminal

A 5.6V Zener diode is connected in reverse bias across a 12V supply through a 1kΩ resistor. What is the Zener current?

• 6.4 mA

• 5.6 mA

• 12 mA

• 0.56 mA

In a voltage regulation circuit, the load is removed suddenly. What happens to the Zener diode if it is already near maximum current rating?

• It maintains regulation safely

• It shuts off and protects itself

• It may get damaged due to excess current

• It starts conducting in forward bias

A Zener diode rated at 9V is used for voltage regulation. If the input voltage drops to 7V, what will be the output across the load?

• 7V

• 9V

• 0V

• 2V

You need a 5V regulated output from a 12V supply using a Zener diode. What should be the minimum value of series resistor if the Zener current must be at least 5 mA and the load draws 10 mA?

• 700 Ω

• 1200 Ω

• 470 Ω

• 350 Ω

In which of the following cases is a Zener diode most appropriately used?

• Converting AC to DC

• Amplifying a small signal

• Protecting a circuit from overvoltage

• Switching high current loads

In a half-wave rectifier circuit using a PN junction diode, what would happen if the diode is connected in the opposite direction?

• The output voltage will increase

• The diode will conduct in both half cycles

• No output voltage will be observed

• The diode will get damaged immediately