# Element 3D Question 91

## Question:

[3D91] A 1 watt, 10 volt zener diode with the following characteristics: I min. = 5 mA, I max. = 480 mA, and Z = 3 ohms; is to be used as part of a voltage regulator. Approximately what size current limiting resistor would set it's bias to the midpoint of it's operating range? |

a} 40 ohms. [correct answer] |

b} 100 ohms. |

c} 400 ohms. |

d} 1 kilo ohms. |

## Challengers Excerpt:

This question looks like it is missing a supply voltage. Is it, or am I missing something?

It also looks like test question zeners have the amazing ability to exceed their Pd ratings and not have a problem!

* Although the challengers excerpt was for this question, it applied to
EL3D 90 as well. It is easy to see how using technology caused
this question and EL3D90 to become incomplete.
--- Joe*

## Response:

Your are correct. It appears due diligence wasn't applied when the FCC created this question.

## Recommendation:

Change the question to:

[3D91] A 5 watt, 10 volt zener diode with the following characteristics: I min. = 5 mA, I max. = 480 mA, and Z = 3 ohms; is to be used as part of a voltage regulator with a 110 VDC source. Approximately what size current limiting resistor would set it's bias to the midpoint of it's operating range? |

a} 40 ohms. [correct answer] |

b} 100 ohms. |

c} 400 ohms. |

d} 1 kilo ohms. |