Under the ohmic-resistor model, how are voltage, current, and resistance related?
A R = V × I
B V = I + R
C V = I × R
D I = V × R
Answer: C. V = I × R. Ohm’s law states that voltage equals current multiplied by resistance for an ohmic component.
Which SI unit measures electric current?
A Ampere
B Volt
C Ohm
D Watt
Answer: A. Ampere. Electric current is measured in amperes (A).
Name the SI unit of potential difference?
A Ampere
B Volt
C Joule
D Coulomb
Answer: B. Volt. Potential difference is measured in volts (V).
Where does an ordinary resistor mainly dissipate electrical energy?
A Mechanical work
B Magnetic field
C Light
D Heat
Answer: D. Heat. A resistor converts electrical energy mainly into thermal energy.
Across series resistors, which quantity stays equal?
A Resistance
B Voltage
C Power
D Current
Answer: D. Current. The same current passes through every element in an unbranched series path.
For ideal parallel branches, which quantity is common?
A Voltage
B Current
C Charge
D Frequency
Answer: A. Voltage. Every parallel branch connects across the same two nodes, so the voltage is equal.
At a circuit junction, Kirchhoff’s current law enforces what?
A Energy conservation
B Voltage multiplication
C Current conservation
D Charge storage
Answer: C. Current conservation. The total current entering a node equals the total current leaving it.
Through an ideal open circuit, how much current flows?
A Zero
B Rated current
C One ampere
D Infinite current
Answer: A. Zero. An open path has infinite ideal resistance, so no current flows.
What voltage appears across an ideal short circuit?
A Infinite voltage
B Zero
C Undefined voltage
D Supply voltage
Answer: B. Zero. An ideal short has zero resistance and therefore zero voltage across it.
Capacitors primarily store energy in which field?
A Magnetic field
B Chemical field
C Electric field
D Thermal field
Answer: C. Electric field. A capacitor stores energy in the electric field between its conductors.
Inductors primarily store energy in which field?
A Electric field
B Thermal field
C Magnetic field
D Chemical field
Answer: C. Magnetic field. Current through an inductor creates the magnetic field that stores its energy.
In the ideal model, a diode conducts mainly in which direction?
A Forward
B Both directions
C Neither direction
D Reverse
Answer: A. Forward. An ideal diode conducts when forward biased and blocks when reverse biased.
Which pair names a PN diode’s terminals?
A Anode and cathode
B Gate and channel
C Emitter and collector
D Source and drain
Answer: A. Anode and cathode. A PN-junction diode has an anode and a cathode.
During forward bias, which side is connected positive?
A N-side
B P-side
C Neither side
D Both sides
Answer: B. P-side. Forward bias connects the P-side to the more positive potential.
In reverse bias, which side is connected positive?
A Both sides
B Neither side
C P-side
D N-side
Answer: D. N-side. Reverse bias makes the N-side more positive than the P-side.
Forward current makes an LED emit what?
A Magnetic field
B Heat
C Sound
D Light
Answer: D. Light. An LED emits light when forward current recombines carriers in its junction.
Which diode maintains a nearly fixed voltage in reverse breakdown?
A Schottky diode
B Photodiode
C Zener diode
D Tunnel diode
Answer: C. Zener diode. A Zener diode is designed to operate in reverse breakdown for voltage regulation.
Rectification converts AC into which form?
A Alternating current
B Pure AC
C Pulsating DC
D Constant AC
Answer: C. Pulsating DC. Rectification changes alternating input into a unidirectional, pulsating output.
How many diodes form a standard bridge rectifier?
A Two
B Four
C Six
D Three
Answer: B. Four. A conventional single-phase bridge rectifier uses four diodes.
AC power transfer between coupled windings is performed by which device?
A Rectifier
B Regulator
C Oscillator
D Transformer
Answer: D. Transformer. A transformer transfers AC energy by electromagnetic induction between windings.
How many terminals does a typical BJT have?
A Two
B Four
C Five
D Three
Answer: D. Three. A bipolar junction transistor has emitter, base, and collector terminals.
In the simple BJT model, what controls collector current?
A Emitter resistance
B Base current
C Collector voltage
D Gate voltage
Answer: B. Base current. In the basic common-emitter model, base current controls collector current.
What controls an insulated-gate MOSFET’s channel?
A Base current
B Gate voltage
C Collector voltage
D Drain current
Answer: B. Gate voltage. The electric field produced by gate-to-source voltage controls a MOSFET channel.
Ideal op amps present what resistance at the input?
A Infinite
B Finite
C One ohm
D Zero
Answer: A. Infinite. An ideal op amp draws no input current, corresponding to infinite input resistance.
Circuit diagrams usually use ground as what?
A Voltage reference
B Current source
C Power sink
D Signal filter
Answer: A. Voltage reference. Ground is commonly chosen as the circuit’s reference potential.