I85PREP
⌘ K
TASC Electronics and Advanced Technologies Level 3 study materials
TASC Electronics and Advanced Technologies Level 3 study resources

TASC Electronics and Advanced Technologies Level 3 practice questions

One question at a time. Build your TASC Electronics and Advanced Technologies Level 3 understanding.

First 50 of 200 questions. Each one lists the choices, the correct answer, and an explanation. The checker at the top of this page saves progress in this browser when it is available.

Continue in the practice tool above to load more questions, 50 at a time.

Question 1Electrical and Electronic Fundamentals

Which quantity is defined as the rate of flow of electric charge past a point in a circuit?

  1. Power
  2. Resistance
  3. Electric current Correct answer.
  4. Electric potential difference

Explanation

Electric current is defined as the rate at which charge passes a given point, measured in amperes where one ampere equals one coulomb per second. Potential difference describes energy per unit charge, resistance opposes current, and power is the rate of energy transfer.

Question 2Electrical and Electronic Fundamentals

A resistor of 220 ohms carries a current of 0.05 A. What is the potential difference across it?

  1. 4.4 V
  2. 0.0044 V
  3. 44 V
  4. 11 V Correct answer.

Explanation

Ohm's law states that voltage equals current multiplied by resistance, so 0.05 A times 220 ohms gives 11 V. Multiplying rather than dividing the two values is the key step in this calculation.

Question 3Electrical and Electronic Fundamentals

Two resistors of 6 ohms and 3 ohms are connected in parallel. What is the combined resistance?

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

Explanation

For two resistors in parallel the reciprocal of the total equals the sum of the reciprocals, so 1/6 plus 1/3 equals 1/2, giving 2 ohms. The combined resistance of a parallel network is always smaller than the smallest individual resistor.

Question 4Electrical and Electronic Fundamentals

A 12 V supply is connected across a 4 ohm resistor. How much power is dissipated in the resistor?

  1. 48 W
  2. 0.33 W
  3. 3 W
  4. 36 W Correct answer.

Explanation

Power can be found from voltage squared divided by resistance, so 12 squared is 144 and dividing by 4 gives 36 W. The same result follows from first finding the current of 3 A and then multiplying voltage by current.

Question 5Electrical and Electronic Fundamentals

Which statement correctly describes the behaviour of electrons in a metallic conductor?

  1. They drift towards the positive terminal under the influence of an applied electric field Correct answer.
  2. They travel at the speed of light along the whole conductor
  3. They are created at the negative terminal and destroyed at the positive terminal
  4. They move only when the conductor is magnetised

Explanation

In a metal, free electrons form a sea of charge carriers that drift in the direction opposite to the conventional current when an electric field is applied. Their drift velocity is very small compared with the speed at which the field propagates through the conductor.

Question 6Electrical and Electronic Fundamentals

A wire of uniform material has its length doubled and its cross-sectional area halved. How does its resistance change?

  1. It doubles
  2. It becomes four times larger Correct answer.
  3. It stays the same
  4. It becomes half as large

Explanation

Resistance is proportional to length and inversely proportional to cross-sectional area, so doubling the length doubles the resistance while halving the area doubles it again. The two effects combine to give a fourfold increase.

Question 7Electrical and Electronic Fundamentals

Which unit is equivalent to one farad?

  1. One joule per coulomb
  2. One coulomb per volt Correct answer.
  3. One volt per coulomb
  4. One coulomb per second

Explanation

Capacitance is charge stored per unit potential difference, so one farad equals one coulomb per volt. The joule per coulomb is the volt, and the coulomb per second is the ampere.

Question 8Electrical and Electronic Fundamentals

A 100 microfarad capacitor is charged to 10 V. How much energy is stored?

  1. 5 mJ Correct answer.
  2. 0.5 mJ
  3. 1 mJ
  4. 10 mJ

Explanation

The energy stored in a capacitor is half the capacitance multiplied by the square of the voltage. Here 0.5 times 100 microfarads times 100 volts squared gives 0.005 J, which is 5 mJ.

Question 9Electrical and Electronic Fundamentals

Which property of a coil primarily determines the magnitude of the emf induced in it by a changing current in a nearby coil?

  1. The physical mass of the coil former
  2. The colour of the insulation on the wire
  3. The rate of change of magnetic flux linking the coil Correct answer.
  4. The dc resistance of the coil

Explanation

Faraday's law states that induced emf is proportional to the rate of change of magnetic flux linkage. Mutual inductance links the changing current in one coil to the flux in the other, so the rate of change of that flux governs the induced emf.

Question 10Electrical and Electronic Fundamentals

A transformer has 500 turns on the primary and 50 turns on the secondary. If the primary is supplied at 240 V, what is the secondary voltage, assuming ideal conditions?

  1. 24 V Correct answer.
  2. 2.4 V
  3. 2400 V
  4. 48 V

Explanation

For an ideal transformer the voltage ratio equals the turns ratio, so the secondary voltage is 240 V multiplied by 50 divided by 500. This gives 24 V, a step-down result consistent with fewer secondary turns.

Question 11Electrical and Electronic Fundamentals

Which statement about a series circuit containing two different resistors is correct?

  1. The current through each resistor is the same Correct answer.
  2. The voltage across each resistor is the same
  3. The total resistance equals the difference between the two values
  4. The larger resistor carries the smaller current

Explanation

In a series circuit there is only one path for charge, so the same current flows through every component. The supply voltage divides between the resistors in proportion to their resistance values.

Question 12Electrical and Electronic Fundamentals

A current of 2 A flows through a resistor for 30 seconds. How much charge passes through it?

  1. 60 C Correct answer.
  2. 15 C
  3. 0.067 C
  4. 600 C

Explanation

Charge equals current multiplied by time, so 2 A times 30 s gives 60 C. Dividing rather than multiplying would give the reciprocal value, which is not the charge transferred.

Question 13Electrical and Electronic Fundamentals

Which material is classified as a semiconductor because its room-temperature conductivity lies between that of metals and insulators?

  1. Silicon Correct answer.
  2. Rubber
  3. Glass
  4. Copper

Explanation

Silicon has four valence electrons and a band gap of roughly one electron-volt, giving it intermediate conductivity that can be controlled by doping. Copper is a metal, while glass and rubber are insulators.

Question 14Electrical and Electronic Fundamentals

In a p-n junction diode that is forward biased, what happens to the depletion region?

  1. It disappears completely and the diode becomes a short circuit
  2. It remains exactly the same width
  3. It widens, increasing the barrier potential
  4. It narrows, lowering the barrier potential Correct answer.

Explanation

Forward bias applies a potential that opposes the built-in junction field, so the depletion region narrows and the barrier is reduced. Once the barrier is low enough, majority carriers cross the junction and current flows readily.

Question 15Electrical and Electronic Fundamentals

A silicon diode with a forward drop of 0.7 V is connected in series with a 330 ohm resistor across a 5 V supply. What current flows?

  1. 17.3 mA
  2. 6.4 mA
  3. 15.2 mA
  4. 13.0 mA Correct answer.

Explanation

The voltage across the resistor is the supply voltage minus the diode drop, giving 4.3 V. Dividing 4.3 V by 330 ohms gives approximately 13.0 mA.

Question 16Electrical and Electronic Fundamentals

Which quantity is measured by an instrument connected in parallel with a component?

  1. Current
  2. Potential difference Correct answer.
  3. Charge
  4. Resistance

Explanation

A voltmeter measures potential difference and must be connected in parallel so that it experiences the same voltage as the component under test. It is designed with a very high internal resistance to avoid drawing significant current.

Question 17Electrical and Electronic Fundamentals

A voltage divider consists of a 10 kilohm and a 5 kilohm resistor in series across a 15 V supply. What is the voltage across the 5 kilohm resistor?

  1. 5 V Correct answer.
  2. 10 V
  3. 7.5 V
  4. 3 V

Explanation

The total series resistance is 15 kilohms, so the current is 1 mA. The voltage across the 5 kilohm resistor is therefore 5 V, which is one third of the supply.

Question 18Electrical and Electronic Fundamentals

What is the principal function of a capacitor in a smoothing circuit?

  1. It converts alternating current into direct current
  2. It blocks direct current while passing alternating current in all cases
  3. It stores charge and releases it to reduce ripple voltage Correct answer.
  4. It amplifies the signal voltage

Explanation

A reservoir capacitor charges near the peak of the rectified waveform and discharges into the load when the supply falls, filling the troughs and reducing ripple. Its effectiveness depends on capacitance and load current.

Question 19Electrical and Electronic Fundamentals

Which statement about a permanent magnet is correct?

  1. Magnetic poles can be isolated by cutting the magnet in half
  2. Its magnetic field lines form closed loops from north to south outside the magnet Correct answer.
  3. Heating a magnet permanently increases its strength
  4. Its field is strongest midway between the poles

Explanation

Magnetic field lines emerge from the north pole and re-enter at the south pole, forming continuous closed loops that pass through the magnet's interior. Cutting a magnet produces two smaller magnets, each with both poles.

Question 20Electrical and Electronic Fundamentals

A coil of 200 turns experiences a flux change of 0.02 Wb in 0.4 s. What average emf is induced?

  1. 40 V
  2. 4 V
  3. 1 V
  4. 10 V Correct answer.

Explanation

Faraday's law gives emf equal to turns multiplied by the rate of change of flux. The rate is 0.02 Wb divided by 0.4 s, which is 0.05 Wb per second, and multiplying by 200 turns gives 10 V.

Question 21Electrical and Electronic Fundamentals

Which effect explains why a conductor carrying current in a magnetic field experiences a force?

  1. The Seebeck effect
  2. The photoelectric effect
  3. The piezoelectric effect
  4. The motor effect Correct answer.

Explanation

A current-carrying conductor in a magnetic field experiences a force whose direction is given by Fleming's left-hand rule; this is the motor effect. The force magnitude depends on current, flux density, length and the angle between conductor and field.

Question 22Electrical and Electronic Fundamentals

An alternating waveform has a peak value of 20 V. What is its root-mean-square value, assuming a sine wave?

  1. 28.3 V
  2. 20 V
  3. 14.1 V Correct answer.
  4. 10 V

Explanation

For a sine wave the rms value equals the peak divided by the square root of two, so 20 V divided by 1.414 gives approximately 14.1 V. The rms value represents the equivalent heating effect of a direct voltage.

Question 23Electrical and Electronic Fundamentals

In a purely capacitive alternating-current circuit, what is the phase relationship between current and voltage?

  1. Current lags voltage by 45 degrees
  2. Current leads voltage by 90 degrees Correct answer.
  3. Voltage leads current by 90 degrees
  4. Current and voltage are in phase

Explanation

In a capacitor the current is proportional to the rate of change of voltage, so the current reaches its peak a quarter cycle before the voltage. This is described as the current leading the voltage by 90 degrees.

Question 24Electrical and Electronic Fundamentals

Which factor determines the capacitance of a parallel-plate capacitor?

  1. Only the current flowing into the plates
  2. The resistance of the connecting wires
  3. The plate area, the plate separation and the permittivity of the dielectric Correct answer.
  4. Only the voltage applied across the plates

Explanation

Capacitance is directly proportional to plate area and permittivity and inversely proportional to plate separation. It is a physical property of the construction and does not depend on the applied voltage in an ideal capacitor.

Question 25Electrical and Electronic Fundamentals

A resistor and an inductor are connected in series to a dc source and the current is observed to rise gradually. Which explanation is correct?

  1. The resistor value increases as it warms up
  2. The inductor stores charge that must be released first
  3. The supply voltage falls gradually to zero
  4. The inductor opposes the change in current by inducing a back emf Correct answer.

Explanation

When current through an inductor changes, a back emf is induced that opposes the change, in accordance with Lenz's law. The current therefore rises exponentially with a time constant equal to inductance divided by resistance.

Question 26Electrical and Electronic Fundamentals

Which statement correctly describes the relationship between resistance, voltage and current in a conductor at constant temperature?

  1. Resistance equals current divided by voltage.
  2. Resistance equals voltage divided by current. Correct answer.
  3. Resistance equals voltage multiplied by current.
  4. Resistance equals voltage divided by the square of the current.

Explanation

Ohm's law states that the current through a conductor is directly proportional to the voltage across it, so V = I x R. Rearranging this gives R = V / I, meaning resistance is the voltage divided by the current. This holds only while temperature and other physical conditions stay constant.

Question 27Electrical and Electronic Fundamentals

Two resistors of 6 ohm and 3 ohm are connected in parallel across a 12 V supply. What is the total current drawn from the supply?

  1. 8 A
  2. 4 A
  3. 6 A Correct answer.
  4. 1.33 A

Explanation

In a parallel circuit each branch receives the full supply voltage, so the branch currents are 12/6 = 2 A and 12/3 = 4 A. The supply current is the sum of the branch currents, giving 6 A. Equivalently, the combined resistance of 2 ohm carries 12 V to produce 6 A.

Question 28Electrical and Electronic Fundamentals

A sinusoidal alternating voltage has an RMS value of 12 V. What is its peak value?

  1. 17 V Correct answer.
  2. 8.5 V
  3. 24 V
  4. 12 V

Explanation

For a sine wave the RMS value equals the peak value divided by the square root of two, approximately 0.707 of the peak. Rearranging gives peak = RMS x 1.414, so 12 V x 1.414 is about 17 V. The RMS value is the equivalent steady value that would deliver the same heating power.

Question 29Electrical and Electronic Fundamentals

A coil of wire is wound on a closed iron core and a steady direct current flows in it. Which change would increase the magnetic flux density inside the core?

  1. Reducing the current while keeping the same number of turns
  2. Replacing the iron core with a plastic former of the same size
  3. Increasing the number of turns while keeping the same current Correct answer.
  4. Introducing an air gap in the magnetic circuit

Explanation

The magnetomotive force of a coil is the product of current and number of turns, so adding turns at constant current raises the magnetising force. A higher magnetising force drives more flux through the same magnetic path. The iron core's high permeability then supports a proportionally larger flux density.

Question 30Electrical and Electronic Fundamentals

Which quantity is defined as the rate at which electrical energy is transferred by a circuit?

  1. Potential difference
  2. Power Correct answer.
  3. Resistance
  4. Charge

Explanation

Power is the rate of energy transfer, measured in watts, where one watt equals one joule per second. In electrical terms it equals the product of voltage and current. Charge, potential difference and resistance describe other properties and are not rates of energy transfer.

Question 31Analog and Digital Circuit Design

Which logic gate produces a HIGH output only when all of its inputs are HIGH?

  1. XOR gate
  2. NAND gate
  3. OR gate
  4. AND gate Correct answer.

Explanation

An AND gate outputs logic 1 only when every input is logic 1; if any input is 0 the output is 0. This follows directly from the truth table, where only the all-ones row yields a 1. The OR, NAND and XOR gates all produce a HIGH output for at least one input pattern that contains a 0.

Question 32Analog and Digital Circuit Design

A resistor of 220 ohms carries a current of 15 mA. What is the voltage across it?

  1. 0.33 V
  2. 33 V
  3. 3.3 V Correct answer.
  4. 1.5 V

Explanation

Ohm's law states V = I x R. Converting 15 mA to 0.015 A and multiplying by 220 ohms gives 3.3 V. Checking the result backwards, 3.3 V divided by 220 ohms returns the original 15 mA.

Question 33Analog and Digital Circuit Design

In a common-emitter BJT amplifier, which quantity is inverted relative to the input signal?

  1. The supply current
  2. The emitter voltage
  3. The base current
  4. The collector voltage Correct answer.

Explanation

When the base current rises, the transistor conducts harder and the collector current increases, so the voltage drop across the collector resistor grows and the collector voltage falls. The output at the collector is therefore 180 degrees out of phase with the input. Base current and emitter voltage follow the input in phase.

Question 34Analog and Digital Circuit Design

What is the primary function of a capacitor in a DC power supply filter?

  1. It limits the current through the load
  2. It steps the mains voltage down to a safe level
  3. It converts alternating current into direct current
  4. It smooths the rectified output by storing and releasing charge Correct answer.

Explanation

A filter capacitor charges near the peak of the rectified waveform and discharges into the load as the waveform falls, reducing ripple. The result is a smoother, more nearly constant DC level. Rectification is done by diodes and voltage scaling is done by a transformer.

Question 35Analog and Digital Circuit Design

Which number system uses only the digits 0 and 1?

  1. Binary Correct answer.
  2. Octal
  3. Decimal
  4. Hexadecimal

Explanation

The binary system is base 2 and therefore has exactly two digit symbols, 0 and 1. Each position represents a power of two, which maps naturally onto the two states of a digital logic signal. Octal uses eight symbols and hexadecimal uses sixteen.

Question 36Analog and Digital Circuit Design

Which component stores data only while power is applied and is commonly built from two cross-coupled logic gates?

  1. A read-only memory cell
  2. A flash memory cell
  3. A shift register
  4. A static RAM cell Correct answer.

Explanation

An SRAM cell is a bistable latch made from cross-coupled inverters, so it holds its state as long as power is present but loses it when power is removed. ROM and flash retain data without power. A shift register moves data along rather than storing a single stable bit by itself.

Question 37Analog and Digital Circuit Design

A 10 kohm and a 20 kohm resistor are connected in series across a 12 V supply. What is the voltage across the 20 kohm resistor?

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

Explanation

The total resistance is 30 kohm, giving a current of 12 V divided by 30 kohm, or 0.4 mA. This current through 20 kohm produces 8 V. The voltage-divider rule gives the same result because the 20 kohm resistor is two thirds of the total resistance.

Question 38Analog and Digital Circuit Design

What is the main advantage of a synchronous digital circuit over an asynchronous one?

  1. It needs no flip-flops
  2. Its behaviour is predictable because changes are timed by a single clock Correct answer.
  3. It cannot suffer from propagation delay
  4. It consumes no static power

Explanation

In a synchronous design all state changes are referenced to a common clock, which makes timing analysis and behaviour prediction straightforward. Asynchronous circuits change in response to events, so hazards and races are harder to control. Neither type eliminates propagation delay, and both can draw static power.

Question 39Analog and Digital Circuit Design

Which expression is the simplified form of the Boolean function F = A'B + AB?

  1. A' + B
  2. A
  3. A + B
  4. B Correct answer.

Explanation

Factoring gives F = B(A' + A). By the complement law, A' + A equals 1, so F = B x 1 = B. The variable A has been eliminated because the function does not depend on it.

Question 40Analog and Digital Circuit Design

A 4-bit binary counter counts up from 0000. What value does it hold after 13 clock pulses?

  1. 1101 Correct answer.
  2. 1110
  3. 1011
  4. 1100

Explanation

Starting at 0000, the counter increments once per pulse, so after 13 pulses it holds the decimal value 13. Converting 13 to binary gives 8 + 4 + 1, which is 1101. The counter wraps to 0000 only after the sixteenth pulse.

Question 41Analog and Digital Circuit Design

What is the purpose of a pull-up resistor on a CMOS input that may be left unconnected?

  1. To reduce the supply voltage
  2. To limit the output current of the driving gate
  3. To define a stable logic HIGH and prevent floating Correct answer.
  4. To increase the input capacitance

Explanation

An unconnected CMOS input can drift to an undefined level and cause excessive current in the input stage. A pull-up resistor provides a defined path to the positive supply so the input rests at a valid HIGH. It does not change the supply voltage or the output drive capability.

Question 42Analog and Digital Circuit Design

A JK flip-flop has J and K both tied HIGH. What happens on each active clock edge?

  1. The output is set to 1
  2. The output is reset to 0
  3. The output holds its previous value
  4. The output toggles Correct answer.

Explanation

With both J and K HIGH the flip-flop is in toggle mode, so the output reverses on every active edge. This behaviour is often used to build divide-by-two counters. Setting and resetting require only one of J or K to be HIGH, and holding requires both to be LOW.

Question 43Analog and Digital Circuit Design

What is the key advantage of a differential amplifier input stage?

  1. It needs no bias current
  2. It has infinite bandwidth
  3. It rejects signals common to both inputs Correct answer.
  4. It produces a single-ended output with no gain

Explanation

A differential stage amplifies the difference between its inputs while attenuating signals that appear equally on both. This common-mode rejection is valuable for rejecting interference and noise. It still requires bias current and has finite bandwidth.

Question 44Analog and Digital Circuit Design

Which statement describes the operation of a diode in reverse bias below its breakdown voltage?

  1. Only a very small leakage current flows Correct answer.
  2. It behaves as a capacitor with large DC current
  3. It conducts heavily like a closed switch
  4. It emits light proportional to current

Explanation

Below breakdown, the depletion region widens and only a small leakage current, typically in the microampere or nanoampere range, flows. The diode behaves much like an open circuit for practical purposes. Heavy conduction occurs only in forward bias or above the reverse breakdown voltage.

Question 45Analog and Digital Circuit Design

What is the output of a 4-input parity generator with inputs 1, 0, 1, 1 when it is configured for even parity?

  1. Undefined
  2. 0
  3. 2
  4. 1 Correct answer.

Explanation

The three HIGH inputs make an odd count of ones. An even-parity output must make the total number of ones even, so it must be 1. Adding this bit brings the count of ones to four, which is even.

Question 46Analog and Digital Circuit Design

In a two-input CMOS NAND gate, when are both the pull-up and pull-down networks active?

  1. They are both active when both inputs are HIGH
  2. They are both active during every transition
  3. They are both active when both inputs are LOW
  4. They are never active at the same time in normal operation Correct answer.

Explanation

A well-designed CMOS gate has complementary networks, so the pull-up conducts only for input combinations that should give a HIGH output and the pull-down only for those giving a LOW. They are therefore not simultaneously on in steady state. Brief overlap can occur only during switching transients, which is not normal operation.

Question 47Analog and Digital Circuit Design

An op-amp in a non-inverting configuration has a feedback resistor of 90 kohm and a ground resistor of 10 kohm. What is the closed-loop gain?

  1. 11
  2. 9
  3. 0.1
  4. 10 Correct answer.

Explanation

For a non-inverting amplifier the gain is 1 + Rf/Rin, which here is 1 + 90/10 = 10. The input signal is applied directly to the non-inverting terminal, so the gain is always at least one. The value 9 would be the magnitude of an inverting amplifier gain with the same resistors.

Question 48Analog and Digital Circuit Design

Why is a Schmitt trigger useful when a slowly changing noisy signal drives a digital input?

  1. It uses hysteresis to give clean, fast output transitions Correct answer.
  2. It amplifies the noise so the signal can be detected
  3. It removes all DC offset from the signal
  4. It increases the input impedance to infinity

Explanation

A Schmitt trigger has separate upper and lower switching thresholds, so noise smaller than the hysteresis band cannot cause repeated toggling. The output snaps between levels once the threshold is crossed. It does not filter DC offset or make the input impedance infinite.

Question 49Analog and Digital Circuit Design

How many select lines are needed for a multiplexer with 16 data inputs?

  1. 16
  2. 8
  3. 2
  4. 4 Correct answer.

Explanation

The number of selectable inputs is 2 raised to the power of the number of select lines. Since 2 to the fourth power is 16, four select lines are required. Eight select lines would address 256 inputs.

Question 50Analog and Digital Circuit Design

A design must detect when a 4-bit input is exactly 1011. Which implementation is most direct?

  1. A four-input OR gate fed by the input bits
  2. A two-input XOR gate comparing the first two bits
  3. A four-input AND gate fed by the true and complemented bits Correct answer.
  4. A flip-flop clocked by the input bits

Explanation

Detecting a specific pattern is an AND of literals, one for each bit in its required state. The bits that must be 1 are used directly and those that must be 0 are inverted, then all four are ANDed. An OR gate cannot enforce a single combination, and a flip-flop stores state rather than decoding it.