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Karnataka KSEAB II PUC Electronics and Hardware (Vocational) study materials
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Karnataka KSEAB II PUC Electronics and Hardware (Vocational) practice questions

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Question 1Basic Electronics and Passive Components

In the standard resistor colour code, a resistor marked brown, black, red, gold has which nominal value and tolerance?

  1. 1 kΩ with ±5 % tolerance Correct answer.
  2. 10 Ω with ±2 % tolerance
  3. 1 kΩ with ±10 % tolerance
  4. 100 Ω with ±5 % tolerance

Explanation

Brown is 1, black is 0 and red is a multiplier of 100, giving 10 × 100 = 1000 Ω. The gold band in the fourth position indicates a tolerance of ±5 %. A silver band would mean ±10 %.

Question 2Basic Electronics and Passive Components

Which statement correctly describes the behaviour of a capacitor in a DC circuit after the supply has been connected for a long time?

  1. It behaves as a fixed resistor whose value equals its reactance
  2. It behaves as a voltage source that keeps rising indefinitely
  3. It behaves as a short circuit because its plates have zero resistance
  4. It behaves as an open circuit because the dielectric blocks steady current Correct answer.

Explanation

A capacitor stores charge on two plates separated by a dielectric, so no steady conduction current flows through it. Once fully charged it blocks direct current and acts as an open circuit, though it still holds a voltage. Reactance only matters for changing signals, not for steady DC.

Question 3Basic Electronics and Passive Components

A diode is tested with a multimeter and reads low resistance in one direction and very high resistance when the probes are swapped. What can be concluded?

  1. The diode is probably healthy and shows normal forward and reverse behaviour Correct answer.
  2. The diode is a zener diode operating in breakdown
  3. The diode is open-circuited internally
  4. The diode is short-circuited in both directions

Explanation

A good PN junction conducts when forward biased and blocks when reverse biased, so a low reading one way and a high reading the other way is expected. A short would read low both ways, and an open would read high both ways.

Question 4Basic Electronics and Passive Components

Three resistors of 2 Ω, 3 Ω and 6 Ω are connected in parallel. What is the equivalent resistance?

  1. 0.5 Ω
  2. 11 Ω
  3. 1 Ω Correct answer.
  4. 3.67 Ω

Explanation

For parallel resistors, 1/R = 1/2 + 1/3 + 1/6 = 3/6 + 2/6 + 1/6 = 6/6 = 1, so R = 1 Ω. The equivalent resistance must always be smaller than the smallest branch resistor, which confirms the answer.

Question 5Basic Electronics and Passive Components

Which property makes a varactor diode useful in a tuned radio circuit?

  1. It latches on once triggered by a gate pulse
  2. It emits light when forward biased
  3. Its forward resistance falls as temperature increases
  4. Its junction capacitance varies with the applied reverse voltage Correct answer.

Explanation

A varactor is operated in reverse bias, where the depletion layer widens or narrows with applied voltage and thereby changes junction capacitance. Connecting it across a tuned circuit lets a DC control voltage shift the resonant frequency electronically.

Question 6Basic Electronics and Passive Components

An LED is to be operated from a 9 V supply drawing 15 mA, and the LED drops 2 V. Which series resistor value is required?

  1. 467 Ω Correct answer.
  2. 133 Ω
  3. 733 Ω
  4. 600 Ω

Explanation

The resistor must drop 9 V − 2 V = 7 V at 15 mA. Using R = V/I gives 7/0.015 ≈ 467 Ω, and the nearest preferred value would be chosen. Using the full supply voltage without subtracting the LED drop is a common error.

Question 7Basic Electronics and Passive Components

Which statement about an electrolytic capacitor is correct?

  1. It is used mainly for high-frequency tuning circuits
  2. It is polarised and must be connected with the correct terminal polarity Correct answer.
  3. It stores charge in a magnetic field between the foils
  4. It has no polarity but a very low leakage current

Explanation

Electrolytic capacitors use a thin oxide film as the dielectric, which gives a large capacitance in a small body but makes the device polarised. Reversing the terminals can damage it or cause failure. Non-polarised types such as ceramic or film are used where polarity cannot be guaranteed.

Question 8Basic Electronics and Passive Components

In a transformer, which quantity is the same on the primary and secondary sides for an ideal transformer?

  1. Power Correct answer.
  2. Current
  3. Voltage
  4. Turns per volt

Explanation

An ideal transformer transfers all input power to the output, so primary power equals secondary power. Voltage and current change in inverse proportion according to the turns ratio. This power equality is what allows step-up or step-down operation without energy gain.

Question 9Basic Electronics and Passive Components

A zener diode with a rated voltage of 5.1 V is used in a regulator circuit. What is its main operating condition?

  1. Zero bias with no current
  2. Reverse bias beyond its breakdown voltage Correct answer.
  3. Forward bias with a series capacitor
  4. Forward bias above 0.7 V

Explanation

A zener regulator works in reverse breakdown, where the voltage across the device stays nearly constant at the zener voltage over a range of currents. A series resistor limits the current so the diode is not destroyed. Forward bias would simply give an ordinary diode drop.

Question 10Basic Electronics and Passive Components

Two capacitors of 6 µF and 3 µF are connected in series. What is the total capacitance?

  1. 2 µF Correct answer.
  2. 4.5 µF
  3. 18 µF
  4. 9 µF

Explanation

Series capacitors combine like parallel resistors: 1/C = 1/6 + 1/3 = 1/6 + 2/6 = 3/6, so C = 2 µF. The total is always less than the smallest capacitor in the series chain.

Question 11Basic Electronics and Passive Components

Which material is classified as a semiconductor used in the manufacture of diodes and transistors?

  1. Mica
  2. Silicon Correct answer.
  3. Nichrome
  4. Copper

Explanation

Silicon is a Group IV element whose controlled doping produces N-type and P-type regions, forming the basis of diodes and transistors. Its stable oxide also makes it convenient for device fabrication.

Question 12Basic Electronics and Passive Components

A resistor is marked 4R7. What is its value?

  1. 0.47 Ω
  2. 47 Ω
  3. 470 Ω
  4. 4.7 Ω Correct answer.

Explanation

In the R-notation system, the letter R marks the decimal point position, so 4R7 means 4.7 Ω. For larger values, letters K and M are used in place of a multiplier, as in 4K7 for 4.7 kΩ.

Question 13Basic Electronics and Passive Components

A capacitor is marked 104. What is its value?

  1. 100 nF Correct answer.
  2. 10 nF
  3. 1000 µF
  4. 104 pF

Explanation

On a three-digit ceramic capacitor, the first two digits give the significant figures and the third gives the number of zeros in picofarads. So 104 means 10 followed by four zeros, that is 100000 pF, which equals 100 nF or 0.1 µF.

Question 14Basic Electronics and Passive Components

In a full-wave bridge rectifier, how many diodes conduct during each half cycle of the AC input?

  1. One
  2. Four
  3. Two Correct answer.
  4. Three

Explanation

A bridge rectifier uses four diodes in a ring, and on each half cycle one diagonal pair conducts while the other pair is reverse biased. The conducting pair changes every half cycle, so the output current always flows the same way.

Question 15Basic Electronics and Passive Components

Which of these is the main function of a heat sink fitted to a power transistor?

  1. To provide electrical isolation from the circuit
  2. To increase the current gain of the transistor
  3. To increase the surface area for dissipating heat Correct answer.
  4. To filter ripple from the supply

Explanation

A heat sink conducts heat away from the transistor case and spreads it over a larger area so convection and radiation can remove it. This keeps the junction temperature within its rated limit. It does not change the electrical characteristics of the device.

Question 16Basic Electronics and Passive Components

A coil of wire wound on a ferrite core is used as an inductor. What effect does inserting the ferrite core have?

  1. It reduces the inductance to nearly zero
  2. It makes the inductor independent of frequency
  3. It increases the inductance for the same number of turns Correct answer.
  4. It converts the inductor into a capacitor

Explanation

Inductance depends on the permeability of the core material, and ferrite has a much higher permeability than air. For the same winding, the core therefore raises the inductance and concentrates the magnetic flux. This is why ferrite cores are common in filters and transformers.

Question 17Basic Electronics and Passive Components

Which statement about a P-N junction diode under forward bias is correct?

  1. The depletion region widens and current falls
  2. The junction behaves as a perfect insulator
  3. The diode emits light in every forward-biased condition
  4. The depletion region narrows and current rises sharply after the knee voltage Correct answer.

Explanation

Forward bias opposes the built-in barrier, so the depletion layer becomes thinner. Once the applied voltage passes the knee, typically about 0.7 V for silicon, the current increases rapidly. This gives the characteristic forward curve of the diode.

Question 18Basic Electronics and Passive Components

A 12 V supply feeds a 4 Ω and an 8 Ω resistor in series. What is the voltage across the 8 Ω resistor?

  1. 8 V Correct answer.
  2. 12 V
  3. 4 V
  4. 6 V

Explanation

The total resistance is 12 Ω, so the current is 12/12 = 1 A. The drop across the 8 Ω resistor is then 1 × 8 = 8 V. This is the voltage divider principle applied to a series network.

Question 19Basic Electronics and Passive Components

Which of these is the correct colour sequence of bands on a 220 Ω resistor with ±5 % tolerance?

  1. Brown, red, red, silver
  2. Orange, orange, brown, gold
  3. Red, red, brown, gold Correct answer.
  4. Red, brown, red, gold

Explanation

220 Ω is written as 22 followed by one zero, so the bands are red (2), red (2), brown (×10) and gold (±5 %). The third band is the multiplier, not a digit.

Question 20Basic Electronics and Passive Components

In a photo-diode circuit, the diode is normally operated in which condition?

  1. Zero bias with the supply disconnected
  2. Forward bias well above the knee
  3. Forward bias with a large series capacitor
  4. Reverse bias Correct answer.

Explanation

A photodiode is operated in reverse bias so that the small reverse leakage current is proportional to the incident light intensity. The light-generated carriers increase this current in a predictable way. Forward bias would swamp the light response with normal diode conduction.

Question 21Basic Electronics and Passive Components

Which statement about the resistance of a typical NTC thermistor as temperature rises is correct?

  1. It becomes infinite
  2. It stays constant
  3. It increases linearly
  4. It decreases Correct answer.

Explanation

NTC stands for negative temperature coefficient, so the resistance falls as temperature increases. This property is used for temperature sensing and inrush-current limiting. A PTC thermistor behaves in the opposite way.

Question 22Basic Electronics and Passive Components

A bridge rectifier is followed by a large smoothing capacitor. What is the main effect of the capacitor?

  1. It reduces the ripple in the output voltage Correct answer.
  2. It converts AC to DC without any diodes
  3. It doubles the output frequency
  4. It increases the peak output voltage

Explanation

The capacitor charges near the peak of each rectified pulse and discharges through the load between pulses, filling in the valleys of the waveform. This reduces the ripple amplitude. The peak voltage is still set by the rectifier and supply, not by the capacitor.

Question 23Basic Electronics and Passive Components

Which of these is a valid reason for using a bleeder resistor across a large capacitor in a power supply?

  1. To increase the capacitance value
  2. To raise the working voltage rating
  3. To convert the capacitor into an inductor
  4. To discharge the capacitor after the supply is switched off Correct answer.

Explanation

A bleeder resistor provides a discharge path so that the capacitor does not remain charged at a dangerous voltage once power is removed. Its value is chosen high enough to waste little power but low enough to discharge safely within a reasonable time.

Question 24Basic Electronics and Passive Components

In a transformer with 500 primary turns and 50 secondary turns, the primary is connected to 230 V AC. What is the secondary voltage?

  1. 2300 V
  2. 230 V
  3. 11.5 V
  4. 23 V Correct answer.

Explanation

The turns ratio is 500:50, or 10:1, so the secondary voltage is 230/10 = 23 V. This is a step-down transformer. The voltage ratio always equals the turns ratio for an ideal transformer.

Question 25Basic Electronics and Passive Components

A circuit needs a stable reference voltage and only a limited current is drawn from it. Which arrangement is most appropriate?

  1. An LED in forward bias with no resistor
  2. A germanium diode in forward bias with no resistor
  3. A zener diode in reverse bias with a series current-limiting resistor Correct answer.
  4. A varactor diode in reverse bias with no resistor

Explanation

A zener in reverse breakdown holds a nearly constant voltage, and the series resistor sets the current within the diode's safe operating range. Without a series resistor the diode current is uncontrolled and the device may be damaged.

Question 26Basic Electronics and Passive Components

In a carbon film resistor, the fourth colour band indicates which property?

  1. Temperature coefficient
  2. Working voltage
  3. Power rating
  4. Tolerance Correct answer.

Explanation

The fourth band on a four-band resistor gives the tolerance, typically ±5% for gold or ±10% for silver. The first two bands give significant digits, the third gives the multiplier, and the fourth gives tolerance. Temperature coefficient and power rating are not indicated by colour bands on standard resistors.

Question 27Basic Electronics and Passive Components

A capacitor is marked 473. What is its value?

  1. 4.7 nF
  2. 47 nF Correct answer.
  3. 470 pF
  4. 470 nF

Explanation

In the three-digit capacitor code, the first two digits are significant figures and the third digit is the number of zeros in picofarads. Thus 473 means 47 followed by three zeros, giving 47,000 pF, which equals 47 nF. This code is widely used on ceramic and film capacitors.

Question 28Basic Electronics and Passive Components

A 12 V supply is connected across a 6 Ω resistor and a 3 Ω resistor in parallel. What is the total current drawn from the supply?

  1. 1.33 A
  2. 2 A
  3. 4 A
  4. 6 A Correct answer.

Explanation

For resistors in parallel, the total resistance is given by 1/R = 1/6 + 1/3 = 1/6 + 2/6 = 3/6, so R = 2 Ω. The total current is then I = V/R = 12/2 = 6 A. Alternatively, the branch currents are 2 A and 4 A, which sum to 6 A.

Question 29Basic Electronics and Passive Components

An inductor is connected across a 10 V DC supply. After the current has reached a steady value, what is the voltage across the inductor?

  1. 10 V
  2. It depends on the inductance value
  3. 0 V Correct answer.
  4. 5 V

Explanation

The voltage across an inductor is given by V = L(di/dt). In steady DC, the current is constant, so di/dt = 0 and the inductor voltage is zero. The inductor behaves like a short circuit (apart from its small winding resistance), and the supply voltage appears across the circuit resistance.

Question 30Basic Electronics and Passive Components

A parallel plate capacitor has air as the dielectric. If a dielectric material of relative permittivity 4 is introduced to completely fill the space between the plates, how does the capacitance change?

  1. It becomes 4 times smaller
  2. It remains the same
  3. It becomes 2 times larger
  4. It becomes 4 times larger Correct answer.

Explanation

The capacitance of a parallel plate capacitor is C = ε₀εᵣA/d, so it is directly proportional to the relative permittivity of the dielectric. Replacing air (εᵣ ≈ 1) with a material of εᵣ = 4 increases the capacitance by a factor of 4. The dielectric reduces the electric field for a given charge, allowing more charge to be stored at the same voltage.

Question 31Semiconductor Devices and Diodes

In a pure intrinsic semiconductor such as silicon at room temperature, which statement correctly describes the charge carriers?

  1. Only holes exist because the valence band is completely full.
  2. The number of free electrons is much larger than the number of holes because silicon is tetravalent.
  3. The number of free electrons equals the number of holes, and both are created by thermal generation. Correct answer.
  4. Only free electrons exist because the conduction band is partially filled.

Explanation

In an intrinsic crystal, thermal energy breaks covalent bonds and each broken bond produces one free electron and one hole, so the two carrier concentrations remain equal. This balance is the defining property of intrinsic conduction, and it is why intrinsic silicon conducts only weakly at room temperature.

Question 32Semiconductor Devices and Diodes

A silicon diode is forward biased. Which bias voltage is normally required before appreciable forward current begins to flow?

  1. About 25 V
  2. About 0.1 V
  3. About 0.7 V Correct answer.
  4. About 5.0 V

Explanation

For a silicon pn junction the barrier potential is roughly 0.7 V, so significant forward current appears only after the applied voltage overcomes this barrier. Germanium junctions need only about 0.3 V for the same effect.

Question 33Semiconductor Devices and Diodes

In a half-wave rectifier using one diode, what is the ripple frequency of the output when the input is a 50 Hz mains supply?

  1. 50 Hz Correct answer.
  2. 150 Hz
  3. 25 Hz
  4. 100 Hz

Explanation

A half-wave rectifier passes only one half of each input cycle, so the output pulses repeat once per input cycle and the ripple frequency equals the supply frequency. A full-wave rectifier would double this value.

Question 34Semiconductor Devices and Diodes

Which property makes a zener diode suitable for voltage regulation?

  1. It operates in the reverse breakdown region with an almost constant voltage across it. Correct answer.
  2. It stores charge and releases it slowly like a capacitor.
  3. It has a very large forward resistance that limits current.
  4. It conducts heavily in forward bias with almost zero voltage drop.

Explanation

A zener diode is designed to be operated in reverse breakdown, where a large change in current produces only a small change in terminal voltage. This near-constant breakdown voltage is what allows it to hold a load voltage steady.

Question 35Semiconductor Devices and Diodes

A light-emitting diode is to be used as an indicator. Which statement about its operating point is correct?

  1. It is forward biased and must be driven from a current source only.
  2. It is forward biased and needs a series resistor to limit current. Correct answer.
  3. It is reverse biased and produces light from leakage current.
  4. It is reverse biased and needs a series resistor to limit current.

Explanation

An LED emits light when forward biased, and its forward voltage is nearly fixed, so a series resistor is used to set the current to a safe value. Without that resistor the diode current would rise until the device is damaged.

Question 36Semiconductor Devices and Diodes

What is the effect of increasing the doping concentration of the p and n regions of a pn junction diode?

  1. The barrier potential falls to zero and the depletion width increases.
  2. The barrier potential increases slightly and the depletion width decreases. Correct answer.
  3. The depletion width increases and the barrier potential decreases sharply.
  4. Both the barrier potential and the depletion width become independent of doping.

Explanation

Heavier doping raises the built-in potential because the contact potential depends on the ratio of acceptor to donor concentrations. It also narrows the depletion region, since the same charge is provided by a smaller width of more heavily doped material.

Question 37Semiconductor Devices and Diodes

A diode is labelled with a maximum forward current of 1 A. In a circuit the diode carries 1.2 A. What is the most likely consequence?

  1. The reverse saturation current will decrease.
  2. The diode will rectify more efficiently.
  3. The forward voltage will fall to zero.
  4. Excessive heating may destroy the junction. Correct answer.

Explanation

The maximum forward current rating is based on the heat the junction can dissipate, so exceeding it raises junction temperature and can cause permanent failure. Ratings must be respected by choosing a higher-current device or adding heat sinking.

Question 38Semiconductor Devices and Diodes

Which material is commonly used for the fabrication of zener diodes because of its sharp breakdown characteristic?

  1. Mica
  2. Silicon Correct answer.
  3. Aluminium
  4. Copper

Explanation

Zener diodes are made from doped silicon because its reverse breakdown is sharp and predictable, giving a well-defined reference voltage. Copper, aluminium and mica are conductors or insulators and cannot form a controllable pn junction.

Question 39Semiconductor Devices and Diodes

A bridge rectifier is fed from a 50 Hz supply. What is the ripple frequency at its output?

  1. 100 Hz Correct answer.
  2. 200 Hz
  3. 25 Hz
  4. 50 Hz

Explanation

A bridge rectifier conducts on both halves of each input cycle, producing two output pulses per cycle. The ripple frequency is therefore twice the supply frequency, that is, 100 Hz.

Question 40Semiconductor Devices and Diodes

A silicon diode with a 0.7 V drop is connected in series with a 330 ohm resistor across a 9 V battery. What is the approximate diode current?

  1. 25 mA Correct answer.
  2. 2.5 mA
  3. 27 mA
  4. 12 mA

Explanation

The resistor sees 9 V minus 0.7 V, that is 8.3 V, and Ohm's law gives 8.3/330 which is about 25 mA. Ignoring the diode drop would give an incorrect, slightly higher value.

Question 41Semiconductor Devices and Diodes

In a full-wave centre-tap rectifier, what is the peak inverse voltage across the non-conducting diode if the peak voltage from each half of the secondary is Vm?

  1. Vm
  2. 0.7 Vm
  3. 2 Vm Correct answer.
  4. Vm/2

Explanation

When one diode conducts, the other sees the sum of the peak voltage of its own half winding and the peak voltage developed across the conducting half, giving 2 Vm. This doubled reverse stress is a key disadvantage of the centre-tap circuit.

Question 42Semiconductor Devices and Diodes

A zener regulator uses a 6 V zener with a 100 ohm series resistor from a 12 V supply. If the load draws negligible current, what is the current through the zener?

  1. 120 mA
  2. 60 mA Correct answer.
  3. 12 mA
  4. 6 mA

Explanation

The series resistor drops 12 V minus 6 V, that is 6 V, so the current is 6/100 which is 60 mA. With negligible load current this entire current flows through the zener.

Question 43Semiconductor Devices and Diodes

Which observation shows that a pn junction diode is conducting in the forward direction?

  1. The current is independent of the applied voltage.
  2. The current rises rapidly once the applied voltage passes the knee voltage. Correct answer.
  3. The current falls sharply as the applied voltage is increased.
  4. The current remains almost constant as the applied voltage is increased.

Explanation

The forward characteristic is exponential, so beyond the knee voltage a small increase in applied voltage produces a large increase in current. This steep rise distinguishes forward conduction from the flat reverse leakage region.

Question 44Semiconductor Devices and Diodes

What is the main function of a filter capacitor connected across the output of a rectifier?

  1. It limits the peak inverse voltage of the rectifier diodes.
  2. It increases the ripple frequency to twice the supply frequency.
  3. It charges at the peaks and discharges through the load, reducing ripple. Correct answer.
  4. It converts alternating current into direct current by blocking one half cycle.

Explanation

The capacitor charges to the peak rectified voltage and then discharges slowly into the load between peaks, smoothing the output. The larger the capacitance and load resistance, the smaller the ripple.

Question 45Semiconductor Devices and Diodes

A diode is tested with a multimeter in diode-check mode and reads about 0.6 V in one direction and shows an open circuit in the other. What does this indicate?

  1. The diode is open in both directions.
  2. The diode is healthy, with a normal forward drop and no reverse conduction. Correct answer.
  3. The diode is leaky in the reverse direction.
  4. The diode is shorted in both directions.

Explanation

A healthy silicon diode shows one forward drop of roughly 0.6 to 0.7 V and appears open when the polarity is reversed. A short would read near zero both ways, and an open would read open both ways.

Question 46Semiconductor Devices and Diodes

Why is a photodiode normally operated in reverse bias?

  1. Reverse bias reduces the depletion region so carriers recombine faster.
  2. Reverse bias eliminates the dark current completely.
  3. Reverse bias causes the diode to emit light like an LED.
  4. Reverse bias widens the depletion region, so light-generated carriers give a larger photocurrent. Correct answer.

Explanation

Reverse bias widens the depletion region and strengthens the field there, so electron-hole pairs created by light are swept out efficiently and add to the photocurrent. The current then varies in proportion to illumination.

Question 47Semiconductor Devices and Diodes

In a varactor diode, what happens to the junction capacitance when the reverse bias voltage is increased?

  1. The capacitance decreases because the depletion layer becomes wider. Correct answer.
  2. The capacitance increases because the depletion layer becomes narrower.
  3. The capacitance stays constant regardless of reverse bias.
  4. The capacitance increases because the depletion layer becomes wider.

Explanation

A varactor acts as a voltage-controlled capacitor; increasing reverse bias widens the depletion layer, which acts as the dielectric spacing, so capacitance falls. This property is used for electronic tuning in radio circuits.

Question 48Semiconductor Devices and Diodes

What is the typical forward voltage drop of a germanium diode compared with a silicon diode?

  1. About 5 V, much higher than silicon
  2. About 1.2 V, higher than the 0.7 V of silicon
  3. About 0.7 V, the same as silicon
  4. About 0.3 V, lower than the 0.7 V of silicon Correct answer.

Explanation

Germanium junctions have a smaller barrier potential, so they begin to conduct at roughly 0.3 V whereas silicon needs about 0.7 V. This lower drop is why germanium was once preferred in low-level detector circuits.

Question 49Semiconductor Devices and Diodes

A diode is used in a circuit where the reverse voltage can reach 80 V. The chosen diode has a peak reverse voltage rating of 60 V. What is the correct engineering action?

  1. Reduce the forward current so the reverse rating improves.
  2. Connect a capacitor in series to raise the reverse rating.
  3. Operate the diode as it is because reverse ratings are only advisory.
  4. Select a diode with a reverse voltage rating safely above 80 V. Correct answer.

Explanation

If the reverse voltage exceeds the peak reverse voltage rating, the junction can break down and the device may be destroyed. The correct fix is to choose a diode whose rating provides a safety margin above the worst-case reverse voltage.

Question 50Semiconductor Devices and Diodes

A 6 V zener is used in a regulator with a 12 V supply and a 200 ohm series resistor. The load draws 20 mA. What current flows through the zener?

  1. 50 mA
  2. 10 mA Correct answer.
  3. 20 mA
  4. 30 mA

Explanation

The series resistor carries 6 V divided by 200 ohms, which is 30 mA, and 20 mA of that goes to the load, leaving 10 mA through the zener. The zener current must stay above its minimum for regulation to hold.