(C). The peak-inverse-voltage rating (PIV) of a rectifier is the maximum voltage the rectifier will handle in the non-conducting direction. Diodes are only intended to allow the flow of current in one direction. In some instances, however, excess voltage may cause current to flow in the opposite direction through a diode. The PIV value is the maximum power that the rectifier diode can handle in this reverse flow situation without being damaged or destroyed.

Hint: The PEAK INVERSE voltage is the PEAK (maximum) voltage in the INVERSE (non-conducting) direction.

For more info see Wikipedia: Rectifier, Peak inverse voltage rating (PIV)

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(A). The peak inverse voltage (PIV) and the average forward current are the two major ratings that must not be exceeded for silicon diode rectifiers.

Rectifier diodes are only rated for being able to handle specific voltage or current loads in either the forward or reverse directions. The amount of power in the forward direction is calculated as the junction threshold voltage (0.7 V for silicon diodes) times the average forward voltage. The PIV value is a rating of the maximum voltage that the diode can handle if current is forced in the backward direction. An overload of power or current in either direction can damage or destroy the circuit.

For more info see Wikipedia: Peak inverse voltage

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\(0.3\) Volts is the approximate junction threshold voltage of a germanium diode.

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This threshold is the voltage over which the diode can conduct significant current. Different materials have different junction threshold voltages, so the value for each diode is determined by the properties of the material(s) used in its construction.

For example, a diode made of silicon has a junction threshold voltage of about \(0.7\) Volts.

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Silly Hint:

G for Germanium is about \(\frac{3}{10}\) (\(0.3\) V) of the way through the alphabet while S for Silicon is about \(\frac{7}{10}\) (\(0.7\) V) of the way through the alphabet.

Silly Hint: the 3rd Reich started in Germany

For more info see Wikipedia: Diode

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(C). To ensure that one diode doesn't carry most of the current, a resistor is usually connected in series with each diode. Two or more diodes can be connected in parallel to increase the current handling capacity. Diodes are rated with the amount of average forward current that they can handle because exceeding this could damage or destroy the diode. By placing a small resistor in series with each parallel diode, the current is matched over each parallel line of the circuit.

For more info see Wikipedia: Diodes

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The approximate junction threshold voltage of a conventional silicon diode is \(0.7\) volts.

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This threshold voltage is the voltage where the diode can start to conduct the greater part of the current. The material a diode is made from is a significant factor in what the threshold voltage will be. For example, the germanium diode has a junction threshold of about \(0.3\) volts.

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Silly Hint:

S for Silicon, S for Seven. Also, the letter S is about \(\frac{7}{10}\) (0.7 volts) of the way through the alphabet. (As opposed to Germanium where G is about .3 the through)

Silicon has (7) letters***

For more info see Wikipedia: Diode

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(A). The Schottky diode has a lower capacitance in an RF switching circuit as compared to a standard silicon diode. This diode has a low threshold voltage and very fast switching action which makes it a good choice for using in various switching circuits.

For more info see Wikipedia: Schottky diode

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The stable operation points for a bipolar transistor used as a switch in a logic circuit are its saturation and cut-off regions. The saturation region acts as a good "full on" switch position, whereas the cut-off region acts as a good "full off" switch position.

For more info see wikipedia: Bipolar junction transistor

HINT: Famous Painter Van Gogh was BIPOLAR. He used SATURATED colors and he CUT OFF his ear.

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The cases of some large power transistors must be insulated from ground to avoid shorting the collector or drain voltage to ground. The case of the transistor may be connected to the collector to keep the transistor from overheating, but having a connection to ground, may cause the collector and transistor to drain or short out.

For more info see Wikipedia: Transistor

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A MOSFET (Metal Oxide Semiconductor Field Effect Transistor) is constructed so that the gate is separated from the channel with a thin insulating layer.

Why? Because the electromagnetic "field" in the name needs a dead end at the gate. The field is created when positive or negative charges accumulate on the gate electrode. The field pushes or pulls the electrons and holes within the nearby N-type and P-type materials, which opens or shuts the channel between gate and source as desired for the circuit under construction.

The pile-up of charges only works because there is nowhere for them to go (open circuit). The gate must be insulated from the rest of the transistor. If there was a short circuit, the charges would follow the path of least resistance, no charges would build up, and the "field effect" wouldn't work correctly.

For more info see Wikipedia: MOSFET

Silly hints:

• The correct answer has the key word "Channel."
• This is kind of a "gotcha" question, so you can think "GATe"+"CHAnnel" for "GAT-CHA."

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The control grid is the element of a triode vacuum tube used to regulate the flow of electrons between cathode and plate.

For more info see Wikipedia: Control grid

Hint: to “regulate” is to “Control” or remember that a triode tube has a control grid.

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(B). A Field Effect Transistor is the device listed which is most like a vacuum tube in its general operating characteristics. It acts like the control grid in a vacuum tube system to control the flow of electrons between the drain and the source, just like the plate and cathode of the tube system.

For more info see Wikipedia: Field-Effect Transistor (FET)

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The screen grid insulates/isolates the control grid from the plate which helps counteract the Miller effect by reducing the grid-to-plate capacitance.

Hint: SCREEN it to reduce it.

For more info see Wikipedia: Vacuum tube

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High discharge current is an advantage of the low internal resistance of nickel-cadmium (NiCd) batteries. This makes them great to use in portable electronic devices and tools which require high current flow.

For more info see Wikipedia: Nickle-cadmium (NiCd) batteries

High Discharge Rate Lithium Polymer Battery 5C

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\(10.5\) volts is the minimum allowable discharge voltage for a standard 12 volt lead acid battery to retain maximum cell life.

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Discharging below this level can cause changes in the chemical nature of the cell which are irreversible, which can damage or destroy the cell.

For more info see Wikipedia: Lead-acid battery

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(D). Carbon-zinc primary cell batteries should NEVER be recharged. The chemical reaction which generates current in these batteries is not reversible. Attempting to recharge the battery can cause acid and heat to be released, burning and corroding whatever it comes into contact with. DO NOT RECHARGE.

For more info see Wikipedia: Carbon-zinc batteries

Silly Hint: Think "Z" in Zinc is at the END of the alphabet. A discharged Carbon-Zinc battery has reached the END of its useful life. Or, remember that Carbon-Zinc batteries are alkaline batteries, which you throw away or recycle when they go dead.

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