Daily review: Relay | Photodiode | Zener Diode Quiz…

Q: What is the primary function of a flyback diode connected in parallel with a relay coil?

To protect switching components from high-voltage inductive spikes — When the relay coil is de-energized, the collapsing magnetic field induces a high voltage spike. The flyback diode provides a path for the current, preventing damage to the driving transistor.

Q: In which mode of operation is a photodiode typically used for high-speed light detection?

Reverse bias mode — Reverse bias mode reduces junction capacitance, allowing for faster response times to changes in incident light.

Q: What happens to a Zener diode when it is operated in the breakdown region?

It maintains a nearly constant voltage across its terminals — The Zener diode is designed to operate in the reverse breakdown region, where it maintains a stable Zener voltage across its terminals regardless of current fluctuations.

Q: A relay is described as 'Form C'. What does this configuration imply?

Single Pole Double Throw (SPDT) — Form C contacts are SPDT, meaning they have a common terminal that switches between a normally closed and a normally open contact.

Q: How does incident light intensity affect the reverse current in a photodiode?

It increases with light intensity — Photodiodes are light-sensitive devices; increased photon absorption generates more electron-hole pairs, thereby increasing the reverse saturation current.

Q: Why must a current-limiting resistor be placed in series with a Zener diode used in a voltage regulator circuit?

To prevent the diode from exceeding its maximum power dissipation rating — Without a series resistor, the Zener diode would draw excessive current upon reaching breakdown, leading to thermal runaway and destruction of the device.

Q: Which of the following describes the 'dropout voltage' of a relay?

The voltage at which the relay armature releases — The dropout voltage is the threshold below which the electromagnetic force is insufficient to hold the armature, causing the relay to switch to its de-energized state.

Q: Which material property is most critical for the spectral response of a photodiode?

The bandgap energy of the semiconductor — The bandgap energy determines the minimum photon energy required to excite electrons to the conduction band, defining the light wavelengths the photodiode can detect.

Q: A Zener diode is used as a clipper circuit. What does it do to the input signal?

It restricts the output voltage to the Zener voltage level — When used as a clipper, the Zener diode limits the signal amplitude by shunting current to ground once the input voltage exceeds the Zener or forward-bias threshold.

Q: What is the function of the armature in an electromechanical relay?

To serve as the moving part that actuates the contacts — The armature is the mechanical lever moved by the electromagnetic force of the coil, which physically closes or opens the relay's electrical contacts.

Question 1 of 10

What is the primary function of a flyback diode connected in parallel with a relay coil?

When the relay coil is de-energized, the collapsing magnetic field induces a high voltage spike. The flyback diode provides a path for the current, preventing damage to the driving transistor.

Question 2 of 10

In which mode of operation is a photodiode typically used for high-speed light detection?

Reverse bias mode reduces junction capacitance, allowing for faster response times to changes in incident light.

Question 3 of 10

What happens to a Zener diode when it is operated in the breakdown region?

The Zener diode is designed to operate in the reverse breakdown region, where it maintains a stable Zener voltage across its terminals regardless of current fluctuations.

Question 4 of 10

A relay is described as 'Form C'. What does this configuration imply?

Form C contacts are SPDT, meaning they have a common terminal that switches between a normally closed and a normally open contact.

Question 5 of 10

How does incident light intensity affect the reverse current in a photodiode?

Photodiodes are light-sensitive devices; increased photon absorption generates more electron-hole pairs, thereby increasing the reverse saturation current.

Question 6 of 10

Why must a current-limiting resistor be placed in series with a Zener diode used in a voltage regulator circuit?

Without a series resistor, the Zener diode would draw excessive current upon reaching breakdown, leading to thermal runaway and destruction of the device.

Question 7 of 10

Which of the following describes the 'dropout voltage' of a relay?

The dropout voltage is the threshold below which the electromagnetic force is insufficient to hold the armature, causing the relay to switch to its de-energized state.

Question 8 of 10

Which material property is most critical for the spectral response of a photodiode?

The bandgap energy determines the minimum photon energy required to excite electrons to the conduction band, defining the light wavelengths the photodiode can detect.

Question 9 of 10

A Zener diode is used as a clipper circuit. What does it do to the input signal?

When used as a clipper, the Zener diode limits the signal amplitude by shunting current to ground once the input voltage exceeds the Zener or forward-bias threshold.

Question 10 of 10

What is the function of the armature in an electromechanical relay?

The armature is the mechanical lever moved by the electromagnetic force of the coil, which physically closes or opens the relay's electrical contacts.

Daily review: Relay | Photodiode | Zener Diode Quiz