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Question 1Electronics fundamentals and basic circuits

A resistor of 220 ohms carries a current of 10 mA. What is the voltage across it?

  1. 22 V
  2. 2.2 V Correct answer.
  3. 220 V
  4. 0.22 V

Explanation

Ohm's law states V = I × R. Converting 10 mA to 0.01 A and multiplying by 220 ohms gives 2.2 V.

Question 2Electronics fundamentals and basic circuits

Three resistors of 60 ohms each are connected in parallel. What is the equivalent resistance?

  1. 20 ohms Correct answer.
  2. 180 ohms
  3. 60 ohms
  4. 30 ohms

Explanation

For identical resistors in parallel, the equivalent resistance equals one value divided by the count. Three 60-ohm resistors in parallel give 60/3 = 20 ohms.

Question 3Electronics fundamentals and basic circuits

Which material is classified as a semiconductor?

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

Explanation

Semiconductors have conductivity between that of conductors and insulators; silicon is the classic example. Copper is a conductor, while rubber and mica are insulators.

Question 4Electronics fundamentals and basic circuits

What is the primary function of a capacitor in a circuit?

  1. To store energy in an electric field Correct answer.
  2. To convert AC to DC
  3. To store energy in a magnetic field
  4. To limit current by resistance

Explanation

A capacitor stores charge and energy in the electric field between its plates. Magnetic-field energy storage is the role of an inductor.

Question 5Electronics fundamentals and basic circuits

A wire carries 2 A for 30 seconds. How much charge passes through the wire?

  1. 32 C
  2. 15 C
  3. 0.067 C
  4. 60 C Correct answer.

Explanation

Charge equals current multiplied by time, Q = I × t. Two amperes for 30 seconds gives 60 coulombs.

Question 6Electronics fundamentals and basic circuits

In a purely resistive AC circuit, what is the phase relationship between voltage and current?

  1. They are 180 degrees out of phase
  2. Voltage leads current by 90 degrees
  3. Current leads voltage by 90 degrees
  4. They are in phase Correct answer.

Explanation

In a resistor, voltage and current rise and fall together, so they are in phase. Reactive elements such as inductors and capacitors introduce phase shifts.

Question 7Electronics fundamentals and basic circuits

Which color band on a resistor indicates a tolerance of plus or minus 5 percent?

  1. Gold Correct answer.
  2. Silver
  3. Red
  4. Brown

Explanation

In the resistor color code, gold denotes a tolerance of plus or minus 5 percent. Silver denotes 10 percent, while brown and red denote 1 and 2 percent respectively.

Question 8Electronics fundamentals and basic circuits

What happens to the total resistance when an additional resistor is connected in series with an existing resistor?

  1. It stays the same
  2. It decreases
  3. It increases Correct answer.
  4. It becomes zero

Explanation

Series resistances add directly, so adding another resistor always increases the total. The individual values simply sum together.

Question 9Electronics fundamentals and basic circuits

A 12 V source is connected across a 4 ohm and an 8 ohm resistor in series. What is the current in the circuit?

  1. 3 A
  2. 1.5 A
  3. 0.5 A
  4. 1 A Correct answer.

Explanation

Series resistances add, giving 12 ohms total. Dividing the 12 V source by 12 ohms yields 1 A.

Question 10Electronics fundamentals and basic circuits

A 9 V battery supplies a circuit drawing 30 mA. What is the power delivered?

  1. 27 W
  2. 270 mW Correct answer.
  3. 0.27 mW
  4. 3 mW

Explanation

Power equals voltage times current, P = V × I. Multiplying 9 V by 0.03 A gives 0.27 W, or 270 mW.

Question 11Electronics fundamentals and basic circuits

Two resistors of 100 ohms and 100 ohms are in parallel, and the combination is in series with a 50 ohm resistor. What is the total resistance?

  1. 250 ohms
  2. 150 ohms
  3. 50 ohms
  4. 100 ohms Correct answer.

Explanation

The parallel pair of equal 100-ohm resistors gives 50 ohms. Adding the series 50-ohm resistor yields 100 ohms total.

Question 12Electronics fundamentals and basic circuits

What is the voltage across a 10 microfarad capacitor holding 50 microcoulombs of charge?

  1. 0.2 V
  2. 500 V
  3. 5 V Correct answer.
  4. 0.5 V

Explanation

The capacitor relation is V = Q / C. Dividing 50 microcoulombs by 10 microfarads gives 5 V.

Question 13Electronics fundamentals and basic circuits

An inductor has a reactance of 100 ohms at a given frequency. If the frequency is doubled while inductance stays constant, what is the new reactance?

  1. 100 ohms
  2. 400 ohms
  3. 50 ohms
  4. 200 ohms Correct answer.

Explanation

Inductive reactance equals 2πfL, so it is directly proportional to frequency. Doubling the frequency doubles the reactance to 200 ohms.

Question 14Electronics fundamentals and basic circuits

Which property of a diode allows it to act as a one-way valve for current?

  1. It conducts easily in forward bias and blocks in reverse bias Correct answer.
  2. It amplifies the input signal
  3. It stores charge between two plates
  4. It has a very high resistance in both directions

Explanation

A diode's pn junction conducts when forward biased and blocks current when reverse biased, giving one-way behavior. This unidirectional conduction is its defining characteristic.

Question 15Electronics fundamentals and basic circuits

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

  1. 5 V Correct answer.
  2. 10 V
  3. 15 V
  4. 7.5 V

Explanation

The divider output equals the source times the ratio of the lower resistor to the total. Here 15 V × 5/15 gives 5 V.

Question 16Electronics fundamentals and basic circuits

What is the RMS value of a sinusoidal voltage with a peak value of 170 V?

  1. 85 V
  2. 170 V
  3. 340 V
  4. 120 V Correct answer.

Explanation

For a sine wave, RMS equals peak divided by the square root of two, roughly 0.707 times peak. Applying this to 170 V gives about 120 V.

Question 17Electronics fundamentals and basic circuits

A circuit has a 6 V supply and a total resistance of 3 ohms. What current flows, and what power is dissipated?

  1. 2 A and 12 W Correct answer.
  2. 0.5 A and 3 W
  3. 2 A and 6 W
  4. 18 A and 108 W

Explanation

Current is V/R = 6/3 = 2 A, and power is V × I = 6 × 2 = 12 W. Both values follow directly from Ohm's law and the power relation.

Question 18Electronics fundamentals and basic circuits

Why is a capacitor often placed across the output of a power supply?

  1. To block DC from reaching the load
  2. To increase the output voltage
  3. To reduce the current rating of the supply
  4. To smooth the ripple in the rectified output Correct answer.

Explanation

A capacitor charges and discharges with the varying rectified waveform, reducing ripple and smoothing the DC output. This filtering action is a common power-supply application.

Question 19Electronics fundamentals and basic circuits

In a bipolar junction transistor operating in the active region, what is the relationship between collector current and base current?

  1. Collector current equals base current
  2. Collector current is independent of base current
  3. Collector current is approximately beta times base current Correct answer.
  4. Collector current is much smaller than base current

Explanation

In the active region the transistor amplifies, and collector current equals beta times base current. Beta is the forward current gain of the device.

Question 20Electronics fundamentals and basic circuits

What is the equivalent resistance of a 30 ohm resistor in parallel with a 60 ohm resistor?

  1. 20 ohms Correct answer.
  2. 45 ohms
  3. 15 ohms
  4. 90 ohms

Explanation

For two resistors in parallel, the product over the sum applies: (30 × 60)/(30 + 60) = 1800/90 = 20 ohms. The result is always smaller than the smallest resistor.

Question 21Electronics fundamentals and basic circuits

A 100 ohm resistor dissipates 4 W. What is the current through it?

  1. 0.04 A
  2. 0.2 A Correct answer.
  3. 25 A
  4. 2 A

Explanation

Using P = I²R, the current is the square root of P/R, which is the square root of 4/100. That equals the square root of 0.04, or 0.2 A.

Question 22Electronics fundamentals and basic circuits

A series RC circuit is driven by a DC source that is suddenly switched on. How does the capacitor voltage behave over time?

  1. It stays at zero permanently
  2. It jumps instantly to the source voltage
  3. It rises exponentially toward the source voltage Correct answer.
  4. It rises linearly without limit

Explanation

The capacitor charges through the resistor, and its voltage approaches the source value exponentially with time constant RC. It never exceeds the source voltage.

Question 23Electronics fundamentals and basic circuits

A source of 10 V with an internal resistance of 2 ohms drives a 8 ohm load. What is the terminal voltage across the load?

  1. 2 V
  2. 5 V
  3. 10 V
  4. 8 V Correct answer.

Explanation

Total resistance is 10 ohms, so the current is 1 A. The terminal voltage equals the current times the load, 1 A × 8 ohms = 8 V.

Question 24Electronics fundamentals and basic circuits

A transformer has 200 turns on the primary and 50 turns on the secondary. If the primary is driven at 120 V, what is the secondary voltage?

  1. 60 V
  2. 480 V
  3. 30 V Correct answer.
  4. 120 V

Explanation

The voltage ratio equals the turns ratio: secondary voltage is primary voltage times secondary turns over primary turns. That is 120 V × 50/200 = 30 V.

Question 25Electronics fundamentals and basic circuits

A circuit draws a current of 5 A at a power factor of 0.8 from a 100 V RMS supply. What is the real power consumed?

  1. 625 W
  2. 300 W
  3. 400 W Correct answer.
  4. 500 W

Explanation

Real power equals V × I × power factor. Multiplying 100 V by 5 A gives 500 VA, and multiplying by 0.8 gives 400 W.

Question 26Electronics fundamentals and basic circuits

In a standard resistor color code, which digit does the color green represent?

  1. 6
  2. 5 Correct answer.
  3. 3
  4. 4

Explanation

The resistor color code assigns digits in order: black 0, brown 1, red 2, orange 3, yellow 4, green 5, blue 6, violet 7, gray 8, white 9. Green therefore stands for the digit 5 wherever a digit band is used.

Question 27Electronics fundamentals and basic circuits

What is the conventional direction of current flow in an external circuit?

  1. Alternating randomly between the two terminals
  2. From the lower potential point to the higher potential point
  3. From the positive terminal to the negative terminal Correct answer.
  4. From the negative terminal to the positive terminal

Explanation

Conventional current is defined as the flow of positive charge, so it is taken to move out of the positive terminal and through the external circuit toward the negative terminal. Electron flow is in the opposite direction.

Question 28Electronics fundamentals and basic circuits

Which quantity is measured by an ammeter, and how is the meter connected?

  1. Current, connected in series with the component Correct answer.
  2. Resistance, connected in parallel with the component
  3. Power, connected in series with the component
  4. Voltage, connected in parallel with the component

Explanation

An ammeter measures current and must carry the current being measured, so it is placed in series with the branch of interest. It is designed to have very low resistance so it does not disturb the circuit.

Question 29Electronics fundamentals and basic circuits

A wire carries 2 A for 30 seconds. How much charge passes a point in the wire?

  1. 32 C
  2. 0.067 C
  3. 15 C
  4. 60 C Correct answer.

Explanation

Current is charge per unit time, so charge equals current multiplied by time: Q = I x t = 2 A x 30 s = 60 C.

Question 30Electronics fundamentals and basic circuits

A 24 V source is connected across a series combination of 6 ohm, 6 ohm, and 12 ohm resistors. What is the voltage across the 12 ohm resistor?

  1. 24 V
  2. 8 V
  3. 6 V
  4. 12 V Correct answer.

Explanation

The series resistance is 6 + 6 + 12 = 24 ohms, so the current is 24 V / 24 ohms = 1 A. The 12 ohm resistor then drops V = I x R = 1 A x 12 ohms = 12 V.

Question 31Electronics fundamentals and basic circuits

Three 12 ohm resistors are connected in parallel. What is the equivalent resistance?

  1. 4 ohms Correct answer.
  2. 12 ohms
  3. 36 ohms
  4. 6 ohms

Explanation

For n equal resistors in parallel, the equivalent resistance is R/n = 12/3 = 4 ohms. Equivalently, 1/Req = 1/12 + 1/12 + 1/12 = 3/12.

Question 32Electronics fundamentals and basic circuits

A 5000 ohm resistor has a current of 2 mA through it. What is the voltage across it?

  1. 100 V
  2. 2.5 V
  3. 10 V Correct answer.
  4. 0.4 V

Explanation

Ohm's law gives V = I x R = 0.002 A x 5000 ohms = 10 V. The current must be converted from milliamperes to amperes before multiplying.

Question 33Electronics fundamentals and basic circuits

Two resistors of 200 ohms and 300 ohms are in parallel, and this combination is connected in series with a 120 ohm resistor. What is the total resistance?

  1. 300 ohms
  2. 180 ohms
  3. 620 ohms
  4. 240 ohms Correct answer.

Explanation

The parallel pair gives (200 x 300)/(200 + 300) = 60000/500 = 120 ohms. Adding the series 120 ohm resistor gives 120 + 120 = 240 ohms.

Question 34Electronics fundamentals and basic circuits

A 60 W lamp is designed for 120 V. What is its resistance under these conditions?

  1. 0.5 ohm
  2. 2 ohms
  3. 7200 ohms
  4. 240 ohms Correct answer.

Explanation

Power relates to voltage and resistance by P = V^2 / R, so R = V^2 / P = 14400/60 = 240 ohms. The rated current is 0.5 A, which also gives R = 120/0.5 = 240 ohms.

Question 35Electronics fundamentals and basic circuits

A 10 V source is connected to a 1 kilohm resistor in series with a 1 microfarad capacitor, and the circuit has been connected for a long time. What is the voltage across the capacitor?

  1. 5 V
  2. 0 V
  3. It depends on the time constant
  4. 10 V Correct answer.

Explanation

Once the DC steady state is reached, the capacitor is fully charged and draws no current, so there is no drop across the resistor. The full source voltage therefore appears across the capacitor.

Question 36Electronics fundamentals and basic circuits

An AC signal has a peak voltage of 100 V. What is the peak-to-peak voltage?

  1. 200 V Correct answer.
  2. 100 V
  3. 70.7 V
  4. 141 V

Explanation

Peak-to-peak voltage spans from the positive peak to the negative peak, which is twice the peak value: 2 x 100 V = 200 V.

Question 37Electronics fundamentals and basic circuits

A 12 V source with a 1 ohm internal resistance drives a 5 ohm load. What is the terminal voltage across the load?

  1. 2 V
  2. 12 V
  3. 6 V
  4. 10 V Correct answer.

Explanation

The total resistance is 1 + 5 = 6 ohms, so the current is 12/6 = 2 A. The load voltage is then 2 A x 5 ohms = 10 V, with the remaining 2 V dropped across the internal resistance.

Question 38Electronics fundamentals and basic circuits

In a series RLC circuit at resonance, what is the relationship between the inductive and capacitive reactances?

  1. The capacitive reactance is larger than the inductive reactance
  2. They are equal in magnitude and cancel each other Correct answer.
  3. The inductive reactance is larger than the capacitive reactance
  4. Both reactances are zero

Explanation

Resonance occurs at the frequency where XL = XC, so the two reactances cancel and the circuit impedance becomes purely resistive. The current is then limited only by the resistance.

Question 39Electronics fundamentals and basic circuits

A parallel circuit has a 6 V source across a 2 ohm and a 3 ohm resistor. What is the total current drawn from the source?

  1. 1.2 A
  2. 5 A Correct answer.
  3. 3 A
  4. 0.83 A

Explanation

Each branch sees the full 6 V, so branch currents are 6/2 = 3 A and 6/3 = 2 A. The source current is their sum, 5 A, which also matches 6 V divided by the 1.2 ohm parallel equivalent.

Question 40Electronics fundamentals and basic circuits

A capacitor of 10 microfarads is charged to 50 V. How much energy is stored in the capacitor?

  1. 0.25 mJ
  2. 12.5 mJ Correct answer.
  3. 500 mJ
  4. 25 mJ

Explanation

The stored energy in a capacitor is given by W = ½CV². Substituting C = 10 µF = 10×10⁻⁶ F and V = 50 V gives W = ½ × 10×10⁻⁶ × 2500 = 0.0125 J, which is 12.5 mJ.

Question 41Test equipment and measurement techniques

Which instrument is used to measure the potential difference between two points in a circuit without significantly altering the current in that branch?

  1. A wattmeter connected in series
  2. An ammeter connected in series
  3. A voltmeter connected in parallel Correct answer.
  4. An ohmmeter connected across the supply

Explanation

A voltmeter is placed in parallel with the component so it senses the potential difference, and it is designed with high internal resistance to draw minimal current. An ammeter is instead inserted in series and has low resistance.

Question 42Test equipment and measurement techniques

On an analog multimeter, what does the 'zero adjust' control for the resistance range do?

  1. Balances the mechanical spring tension of the movement
  2. Calibrates the AC voltage scale against a reference source
  3. Compensates for the internal battery voltage so the needle reads zero ohms with the probes shorted Correct answer.
  4. Sets the meter needle to full-scale deflection before each reading

Explanation

Because resistance measurement relies on an internal cell whose voltage falls over time, the meter must be zeroed by shorting the probes and adjusting so the needle sits at the zero-ohm end of the scale. This compensates for the battery and lead resistance.

Question 43Test equipment and measurement techniques

An oscilloscope probe set to '10X' divides the signal by ten. What is the main reason this setting is preferred for high-frequency measurements?

  1. It raises probe input impedance and lowers capacitive loading on the circuit Correct answer.
  2. It increases the displayed amplitude for easier viewing
  3. It doubles the bandwidth of the oscilloscope's vertical amplifier
  4. It converts the signal from AC to DC coupling

Explanation

A 10X probe places a large series resistance and a compensating capacitor at the tip, which raises input impedance and reduces capacitive loading so the circuit under test is disturbed less. It attenuates rather than amplifies the signal.

Question 44Test equipment and measurement techniques

Which measurement is most appropriate for determining the true RMS value of a distorted, non-sinusoidal AC waveform?

  1. A true-RMS (thermal or digital computing) meter Correct answer.
  2. A peak-reading meter scaled by 0.707
  3. An average-reading meter scaled by 1.11
  4. A moving-coil meter with a rectifier

Explanation

True-RMS instruments compute the heating-equivalent value directly, so they remain accurate for distorted waveforms. Average- and peak-reading meters rely on form-factor scaling valid only for sine waves.

Question 45Test equipment and measurement techniques

What does the bandwidth specification of an oscilloscope describe?

  1. The range of input voltages the front end can accept
  2. The frequency at which the displayed amplitude falls to 70.7 percent of the low-frequency value Correct answer.
  3. The maximum record length it can store in memory
  4. The maximum sample rate of its analog-to-digital converter

Explanation

Bandwidth is the upper frequency at which the vertical system response drops 3 dB, i.e. to about 70.7 percent of the reference amplitude. Sample rate, input range and memory depth are separate specifications.

Question 46Test equipment and measurement techniques

A current clamp is placed around a single conductor carrying 5 A DC. A clamp meter rated for DC reads a value. What principle allows a Hall-effect clamp to measure DC current?

  1. The Hall voltage produced by the magnetic field in a semiconductor element Correct answer.
  2. Capacitive coupling between the jaw and the conductor
  3. Resistive shunting of the conductor inside the jaw
  4. Faraday induction from the steady magnetic field

Explanation

A steady DC current produces a steady magnetic field that induces no voltage by induction, so a Hall sensor is used to convert the field into a proportional voltage. Induction-type clamps respond only to changing fields and therefore to AC.

Question 47Test equipment and measurement techniques

When measuring the resistance of a component in a circuit, what precaution is essential for a valid reading?

  1. The probes must be connected in series with the supply
  2. The meter must be set to the AC voltage range
  3. The component must be isolated or the circuit de-energized Correct answer.
  4. The circuit must be energized at rated voltage

Explanation

An ohmmeter supplies its own small test current, so any external voltage or parallel path will corrupt the reading and may damage the meter. The component should be isolated or the circuit de-energized.

Question 48Test equipment and measurement techniques

A digital multimeter's accuracy is stated as +/- (0.5 percent of reading + 2 digits) on the 20 V range with a 3.5-digit display. For a reading of 10.00 V, what is the approximate total uncertainty?

  1. 0.07 V Correct answer.
  2. 0.50 V
  3. 0.02 V
  4. 0.05 V

Explanation

The percentage term is 0.5 percent of 10.00 V, or 0.05 V, and the two-digit term on a display resolving 0.01 V adds 0.02 V, giving about 0.07 V total. The two contributions add directly in the specification.

Question 49Test equipment and measurement techniques

What is the purpose of the timebase control on an oscilloscope?

  1. To select AC or DC input coupling
  2. To set the vertical volts-per-division scaling
  3. To adjust the trace brightness
  4. To set the horizontal sweep rate so the waveform spans a known time Correct answer.

Explanation

The timebase sets how long each horizontal division represents, allowing the period and frequency of a waveform to be read from the display. Vertical scaling and coupling are separate controls.

Question 50Test equipment and measurement techniques

A technician needs to measure a 100 MHz sine wave. Which oscilloscope bandwidth gives adequate amplitude accuracy?

  1. 100 MHz
  2. 20 MHz
  3. 200 MHz Correct answer.
  4. 50 MHz

Explanation

A common rule is to choose scope bandwidth of at least three to five times the signal frequency so the displayed amplitude is not significantly attenuated. For 100 MHz, 200 MHz is the only option providing margin.