Electronics Quiz
Questions: 16 · 10 minutes
1. Why is a small decoupling capacitor often placed close to an integrated circuit's power pins?
To ensure every signal becomes digital
To increase the circuit's DC supply voltage permanently
To supply brief local current demands and reduce supply noise
To replace the need for a ground connection
2. A fuse repeatedly opens in a circuit. Why is replacing it with a much higher-current fuse generally unsafe without first finding the fault?
It can allow excessive current to overheat wiring or components
A higher-current fuse makes all semiconductor signals alternate
A higher-current fuse always lowers the supply voltage
It prevents the circuit from drawing any current
3. For a two-input AND gate, when is the output logic high?
Only when both inputs are high
When either input is high, including when only one is high
Only when both inputs are low
Whenever the two inputs are different
4. Using the standard resistor color code, what nominal value is indicated by brown, black, and red bands as the first three bands?
100 Ω
1 kΩ
10 kΩ
1 MΩ
5. You want to measure the voltage across a resistor in a powered circuit. How should a multimeter set to voltage mode be connected?
In series with the resistor after opening the circuit
In parallel across the resistor
Across the supply only, regardless of the resistor's location
Between ground and an unconnected probe tip
6. Why is a resistor commonly connected in series with an LED?
To make the supply voltage alternate
To store charge after power is removed
To limit current through the LED
To convert the LED into a switch
7. A sine-wave AC signal measures 10 V RMS. Approximately what is its peak voltage?
5 V
7.07 V
20 V
14.1 V
8. A rectifier diode is reverse-biased at a voltage well below its breakdown rating. What does the idealized model predict?
It conducts as though it were a closed switch
It produces a fixed forward-voltage drop while conducting heavily
It blocks current apart from negligible leakage
It behaves as a charged battery
9. An ideal capacitor is connected to a constant DC source. After the charging transient has fully settled, how does the capacitor behave?
Like an open circuit with no steady-state current
Like a resistor whose value steadily decreases
Like an AC voltage source
Like a short circuit carrying maximum current
10. According to Kirchhoff's current law, what is true at an electrical node?
Every branch connected to the node has the same resistance
The total current entering equals the total current leaving
Voltage must always be zero at the node
The branch with the highest resistance carries all the current
11. In a basic low-side switch using an NPN transistor, what typically allows current to flow from collector to emitter?
Sufficient base drive relative to the emitter
Reversing the collector and emitter supply polarity
Removing every connection from the base
Placing the transistor in series with an uncharged capacitor only
12. A 9 V source is connected across a 3 kΩ resistor. Ignoring source resistance, what current flows through the resistor?
0.33 mA
3 mA
27 mA
3 A
13. An oscilloscope trace shows a repeating waveform with a period of 2 ms. What is the waveform's frequency?
2 Hz
50 Hz
2 kHz
500 Hz
14. Three lamps are connected in a single series loop. One lamp fails open-circuit. What happens to the loop?
The other lamps become brighter because they receive more voltage
Current bypasses the failed lamp automatically
The source voltage falls to zero
Current stops through every lamp in the loop
15. An ideal non-inverting op-amp circuit has a 9 kΩ feedback resistor and a 1 kΩ resistor from the inverting input to ground. What is its closed-loop voltage gain?
9
0.1
10
1
16. A device draws 0.5 A from a 12 V supply. Approximately how much electrical power does it consume?
0.042 W
5.5 W
12.5 W
6 W