Design and implementation of an Arduino Uno and IR sensor-based detection system
Easy
A.Crystal oscillator
B.Relay coil
C.Push button
D.Photodiode
Correct Answer: Photodiode
Explanation:
A photodiode detects infrared light reflected from a nearby object.
Incorrect! Try again.
14What is the purpose of the potentiometer on many IR sensor modules?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Easy
A.To connect the USB cable
B.To store sensor readings
C.To increase program memory
D.To adjust detection sensitivity
Correct Answer: To adjust detection sensitivity
Explanation:
The potentiometer is used to set the distance or sensitivity threshold for detection.
Incorrect! Try again.
15Which Arduino Uno pin group is intended for digital input and output?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Easy
A.Analog reference pins
B.Power pins
C.Digital pins
D.USB shield pins
Correct Answer: Digital pins
Explanation:
Digital pins are used to read or produce binary electrical signals.
Incorrect! Try again.
16What is the usual logic value of a HIGH digital signal?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Easy
A.A stored program
B.Logic 1
C.No connection
D.Logic 0
Correct Answer: Logic 1
Explanation:
In digital logic, HIGH generally represents logic 1, while LOW represents logic 0.
Incorrect! Try again.
17Which software is commonly used to write and upload programs to an Arduino Uno?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Easy
A.Arduino IDE
B.Image viewer
C.Spreadsheet editor
D.Web browser
Correct Answer: Arduino IDE
Explanation:
The Arduino IDE is used to write, compile, and upload sketches to the Arduino Uno.
Incorrect! Try again.
18What is an Arduino program commonly called?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Easy
A.A sketch
B.A terminal
C.A register
D.A waveform
Correct Answer: A sketch
Explanation:
An Arduino program is commonly called a sketch.
Incorrect! Try again.
19Why is a common ground needed between the Arduino and IR sensor?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Easy
A.To erase the Arduino program
B.To increase infrared brightness
C.To replace the power supply
D.To provide a shared reference
Correct Answer: To provide a shared reference
Explanation:
A common ground gives the Arduino and sensor the same voltage reference for reliable signals.
Incorrect! Try again.
20What can an Arduino do when an object is detected by an IR sensor?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Easy
A.Change its processor
B.Turn on an LED
C.Recharge the sensor battery
D.Increase the object size
Correct Answer: Turn on an LED
Explanation:
The Arduino can respond to detection by controlling an output such as an LED, buzzer, or relay.
Incorrect! Try again.
21An IR sensor module gives a LOW output when an object is detected. Which Arduino Uno code correctly turns on an LED connected to pin 13 when the object is present?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Medium
Correct Answer: if (digitalRead(sensorPin) == LOW) digitalWrite(13, HIGH);
Explanation:
Since the module produces LOW during detection, the program must read the digital sensor pin and set the LED output HIGH.
Incorrect! Try again.
22Why is a common ground connection required between an Arduino Uno and an IR sensor module?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Medium
A.It converts the sensor output into analog voltage
B.It prevents the Arduino from requiring a power supply
C.It provides a shared voltage reference for signals
D.It increases the sensor's infrared wavelength
Correct Answer: It provides a shared voltage reference for signals
Explanation:
The Arduino interprets the sensor signal relative to ground. Without a common ground, the logic level may be unstable or incorrectly detected.
Incorrect! Try again.
23An IR obstacle sensor is connected to digital pin 7, and its output is active HIGH. Which initialization is appropriate?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Medium
A.pinMode(7, OUTPUT);
B.analogWrite(7, INPUT);
C.digitalWrite(7, INPUT);
D.pinMode(7, INPUT);
Correct Answer: pinMode(7, INPUT);
Explanation:
A sensor output must be read by the Arduino, so the corresponding pin is configured as an input.
Incorrect! Try again.
24The detection range of an IR module changes when its onboard potentiometer is adjusted. What does this potentiometer usually control?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Medium
A.The infrared LED color
B.The serial communication speed
C.The Arduino clock frequency
D.The comparator's detection threshold
Correct Answer: The comparator's detection threshold
Explanation:
The potentiometer changes the reference level used by the comparator, which changes the distance or reflected IR level required to trigger detection.
Incorrect! Try again.
25An LED is connected directly between an Arduino output pin and ground. Why should a series resistor be included?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Medium
A.To increase the Arduino supply voltage
B.To convert digital output into serial data
C.To reverse the LED's polarity
D.To limit current through the LED
Correct Answer: To limit current through the LED
Explanation:
The resistor restricts current to a safe value, protecting both the LED and the Arduino output pin.
Incorrect! Try again.
26An IR sensor output repeatedly changes between HIGH and LOW when an object is stationary near the detection boundary. Which software method is most suitable for reducing false switching?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Medium
A.Increase the serial monitor baud rate
B.Require a stable state for several readings
C.Set every unused pin to analog input
D.Change the LED resistor to a larger value
Correct Answer: Require a stable state for several readings
Explanation:
Reading the sensor several times and accepting a state only after consistent results provides simple software filtering near the switching threshold.
Incorrect! Try again.
27Which statement best describes the role of the IR receiver in a typical reflective obstacle sensor?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Medium
A.It detects reflected infrared radiation
B.It stores the detected object's distance
C.It generates the Arduino program clock
D.It regulates current to the indicator LED
Correct Answer: It detects reflected infrared radiation
Explanation:
The receiver responds to infrared energy reflected from a nearby object, allowing the circuit to determine whether an object is present.
Incorrect! Try again.
28A sensor module operates at 5 V, while its output is connected to Arduino Uno digital pin 8. Which connection is correct?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Medium
A.VCC to pin 8, GND to 5 V, OUT to GND
B.VCC to Vin, GND to pin 8, OUT to the USB shield
C.VCC to GND, GND to 5 V, OUT to pin 8
D.VCC to 5 V, GND to GND, OUT to pin 8
Correct Answer: VCC to 5 V, GND to GND, OUT to pin 8
Explanation:
The module needs power and a shared reference, while its signal terminal must connect to the selected Arduino input pin.
Incorrect! Try again.
29What is the main purpose of using Serial.begin(9600) in an IR detection project?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Medium
A.To provide regulated power to the sensor module
B.To set the IR transmitter's emission frequency
C.To configure communication with the Serial Monitor
D.To select the sensor's physical detection range
Correct Answer: To configure communication with the Serial Monitor
Explanation:
Serial.begin(9600) sets the data rate for communication between the Arduino and a computer through the serial interface.
Incorrect! Try again.
30A detection system should keep an alarm active while an object remains in front of the sensor. Which control structure is most appropriate?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Medium
A.Use delay without reading the sensor again
B.Use a one-time statement in setup only
C.Use analogWrite without checking the sensor
D.Use an if-else statement based on sensor state
Correct Answer: Use an if-else statement based on sensor state
Explanation:
The loop can repeatedly evaluate the sensor and keep the alarm on for detection and off when the object is absent.
Incorrect! Try again.
31Why can a black object be detected less reliably by a reflective IR sensor than a white object?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Medium
A.Black objects disable the Arduino input circuit
B.Black surfaces generally reflect less infrared light
C.Black objects emit visible light instead of infrared light
D.Black surfaces always produce a higher supply voltage
Correct Answer: Black surfaces generally reflect less infrared light
Explanation:
Dark surfaces commonly absorb more infrared radiation, producing a weaker reflected signal at the receiver.
Incorrect! Try again.
32An IR sensor is connected to pin 2, and an indicator LED is connected to pin 9. Which pair of declarations matches this arrangement?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Medium
A.const int sensorPin = 9; const int ledPin = 2;
B.const int sensorPin = 2; const int ledPin = 9;
C.const int sensorPin = 0; const int ledPin = 1;
D.const int sensorPin = A2; const int ledPin = A9;
Correct Answer: const int sensorPin = 2; const int ledPin = 9;
Explanation:
The variable assignments must match the physical connections: pin 2 reads the sensor and pin 9 controls the LED.
Incorrect! Try again.
33What is the likely result if an IR sensor's OUT terminal is accidentally connected to an Arduino output pin configured as OUTPUT?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Medium
A.The IR receiver stops needing a common ground
B.The sensor and Arduino outputs may conflict
C.The Arduino increases the sensor detection range
D.The sensor automatically becomes an analog input
Correct Answer: The sensor and Arduino outputs may conflict
Explanation:
Driving an Arduino pin while the sensor also drives the same line can cause contention, incorrect readings, or excessive current.
Incorrect! Try again.
34An IR sensor indicates detection with LOW, but the program activates the alarm with HIGH. Which change fixes the logical error?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Medium
A.Increase the delay time without changing the condition
B.Invert the condition used to test the sensor
C.Move the sensor wire to the USB connector
D.Replace digitalRead with analogWrite
Correct Answer: Invert the condition used to test the sensor
Explanation:
The program must test for LOW when detection is active LOW, or equivalently use a condition such as sensorState == LOW.
Incorrect! Try again.
35Why should an IR sensor and its target generally be kept aligned during testing?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Medium
A.Alignment changes the USB communication protocol
B.Alignment determines the Arduino's program memory size
C.Alignment affects the amount of reflected IR received
D.Alignment controls the resistor tolerance automatically
Correct Answer: Alignment affects the amount of reflected IR received
Explanation:
The direction and angle of reflection influence how much infrared energy reaches the receiver, affecting detection reliability.
Incorrect! Try again.
36Which sequence represents a suitable Arduino program structure for an IR detection system?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Medium
C.Configure pins, read sensor, control output, repeat
D.Start serial output, remove power, configure pins, stop
Correct Answer: Configure pins, read sensor, control output, repeat
Explanation:
Pin setup belongs in setup(), while reading the sensor and controlling the response should occur repeatedly in loop().
Incorrect! Try again.
37A sensor output is connected to an Arduino input, but the reading changes randomly when the sensor is disconnected. What is the most likely cause?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Medium
A.The input pin is floating
B.The LED has excessive brightness
C.The USB cable is too short
D.The Arduino has too many comments
Correct Answer: The input pin is floating
Explanation:
A disconnected input has no defined logic level and can respond to electrical noise. A pull-up or pull-down arrangement can provide a stable default state.
Incorrect! Try again.
38An Arduino Uno must count an object each time it passes the IR sensor, rather than counting repeatedly while it remains present. What programming technique is needed?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Medium
A.Detect a transition between absent and present states
B.Keep increasing the counter every loop cycle
C.Place the counter declaration inside setup only
D.Use a constant HIGH output for the sensor pin
Correct Answer: Detect a transition between absent and present states
Explanation:
Counting on the change from an absent state to a present state produces one count per arrival instead of many counts for one object.
Incorrect! Try again.
39Which change can help prevent an Arduino output pin from being overloaded when driving an external buzzer circuit?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Medium
A.Connect the buzzer directly to the input pin
B.Short the buzzer terminals to the 5 V rail
C.Remove the common ground from the circuit
D.Use a transistor driver and suitable protection
Correct Answer: Use a transistor driver and suitable protection
Explanation:
A transistor allows the Arduino to control a higher-current load while reducing the current supplied directly by the microcontroller pin.
Incorrect! Try again.
40An IR detection circuit works indoors but gives false detections under strong sunlight. What is a practical improvement?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Medium
A.Replace digitalRead with pinMode
B.Shield the sensor from ambient infrared light
C.Increase the Arduino reset frequency
D.Disconnect the sensor ground during operation
Correct Answer: Shield the sensor from ambient infrared light
Explanation:
Sunlight contains infrared radiation that can interfere with the receiver. Physical shielding and careful sensor positioning can reduce this interference.
Incorrect! Try again.
41An IR obstacle sensor is connected to Arduino Uno digital pin D2 and produces a LOW output when an object is detected. The object remains in front of the sensor for 80 ms, but the detection must be accepted only if the signal is LOW continuously for at least 50 ms. Which implementation best satisfies this requirement without blocking other time-critical tasks?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Hard
A.Count exactly 50 loop iterations after the first LOW reading
B.Use analogRead() and accept when the value exceeds 50
C.Record millis() at the first LOW and accept when LOW persists for 50 ms
D.Use delay(50) after every LOW reading
Correct Answer: Record millis() at the first LOW and accept when LOW persists for 50 ms
Explanation:
A timestamp-based state machine measures elapsed time without blocking the processor. The condition is accepted only when the input remains LOW for the required 50 ms.
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42An IR receiver module connected to an Arduino Uno gives an unstable digital output when a motor starts. The sensor and motor use the same 5 V supply. Which hardware change most directly reduces supply-induced false detections?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Hard
A.Add local decoupling near the sensor and separate motor return paths
B.Replace the digital input with an unused PWM output
C.Increase the sensor threshold by changing the Arduino clock speed
D.Connect the sensor ground through the motor winding
Correct Answer: Add local decoupling near the sensor and separate motor return paths
Explanation:
A local bypass capacitor and controlled grounding reduce voltage disturbances and ground bounce produced by motor current changes. Software filtering alone does not remove the supply disturbance.
Incorrect! Try again.
43A reflective IR sensor is calibrated using a white target, but the system later detects a black target at the same distance inconsistently. What is the most appropriate design response?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Hard
A.Use a fixed threshold selected only from the white-target reading
B.Increase the Arduino supply voltage above 5 V
C.Characterize target reflectivity and calibrate the detection threshold accordingly
D.Disable ambient-light compensation to make the output digital
Correct Answer: Characterize target reflectivity and calibrate the detection threshold accordingly
Explanation:
Reflective IR sensors depend on surface reflectivity, distance, and alignment. A threshold must be selected from the expected target and background ranges, often with hysteresis or calibration.
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44A sensor output is connected to Arduino Uno pin D2, and an interrupt is configured for CHANGE. A moving object causes 12 transitions within 3 ms because of surface texture. Which strategy best prevents one object from being counted multiple times?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Hard
A.Replace CHANGE with LOW and keep the same counting logic
B.Use edge qualification and ignore further events during a timed lockout
C.Increment the count on every interrupt transition
D.Disable interrupts permanently after the first transition
Correct Answer: Use edge qualification and ignore further events during a timed lockout
Explanation:
Texture-induced transitions must be filtered. Qualifying the required edge and applying a timed lockout or state-based re-arm prevents repeated counts while preserving later objects.
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45An Arduino Uno reads an analog IR receiver on A0. With the sensor disconnected, the reading changes randomly between 0 and 1023. Which conclusion is most defensible?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Hard
A.The ADC is automatically generating a valid distance measurement
B.The floating input is picking up noise and needs a defined electrical state
C.The IR emitter is operating at an excessive duty cycle
D.The Arduino reference voltage has become exactly zero
Correct Answer: The floating input is picking up noise and needs a defined electrical state
Explanation:
A disconnected analog input has no defined voltage and can capture environmental electrical noise. A suitable pull-down, pull-up, or active sensor connection establishes a valid input level.
Incorrect! Try again.
46A 5 V IR sensor module has an output that may reach 5 V, while the receiving controller input is a 3.3 V-only device. Which interface is the safest general solution?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Hard
A.Configure the receiving pin as an analog output
B.Use a resistor divider or a proper 5 V-to-3.3 V level shifter
C.Add a capacitor in series and leave the input otherwise unchanged
D.Connect the output directly because logic inputs always tolerate 5 V
Correct Answer: Use a resistor divider or a proper 5 V-to-3.3 V level shifter
Explanation:
A 5 V signal can exceed the absolute maximum rating of a 3.3 V input. Voltage scaling or a level-shifting circuit limits the input to a safe logic range.
Incorrect! Try again.
47An Arduino Uno detection system must operate for several hours from a battery. The IR emitter is continuously enabled even when no measurement is being made. Which modification most effectively reduces average sensor power while preserving reliable detection?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Hard
A.Increase serial monitor output frequency
B.Pulse the IR emitter and sample synchronously when detection is needed
C.Set the sensor input pin to OUTPUT-HIGH continuously
D.Increase the ADC resolution by changing analogRead() syntax
Correct Answer: Pulse the IR emitter and sample synchronously when detection is needed
Explanation:
Duty-cycling the emitter reduces its average current. Sampling after the emitter stabilizes and comparing the response with the emitter off can also improve immunity to ambient light.
Incorrect! Try again.
48Two IR detection sensors are installed 8 cm apart, but each emitter spreads radiation widely and both receivers respond to the same object. Which change most directly improves spatial discrimination?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Hard
A.Read both inputs only after calling delay(1000)
B.Increase the baud rate of the serial interface
C.Replace both sensor grounds with separate floating grounds
D.Use optical shielding and narrower emitter-receiver alignment
Correct Answer: Use optical shielding and narrower emitter-receiver alignment
Explanation:
Mechanical baffles, controlled geometry, and narrower optical fields reduce cross-coupling. Timing multiplexing can further help, but optical isolation directly addresses the shared field of view.
Incorrect! Try again.
49An IR sensor output is active LOW. The Arduino code uses pinMode(sensorPin, INPUT_PULLUP), but the sensor output is a push-pull output that drives HIGH during detection. What is the primary concern?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Hard
A.The sensor output and pull-up necessarily create a damaging short circuit
B.The software polarity and assumed idle state may be interpreted incorrectly
C.The ADC loses all resolution on digital pins
D.The pull-up changes the Arduino clock frequency
Correct Answer: The software polarity and assumed idle state may be interpreted incorrectly
Explanation:
A push-pull output can generally coexist with a weak pull-up, but the code must match the actual active level and idle behavior. Incorrect polarity causes inverted or false detections.
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50A detection routine stores the current sensor state in a variable shared with an interrupt service routine. Which declaration is required when the variable can change asynchronously and is read in the main program?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Hard
A.static double sensorState
B.volatile bool sensorState
C.register char sensorState
D.const int sensorState
Correct Answer: volatile bool sensorState
Explanation:
The volatile qualifier tells the compiler that the value can change outside normal program flow, so it must not optimize away required reads. Shared multi-byte data may additionally require atomic access.
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51An Arduino Uno measures the time between IR sensor edges using micros(). The measurement occasionally becomes incorrect after the timer counter wraps around. Which expression is wraparound-safe for unsigned timestamps now and previous?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Hard
A.if (now > previous + interval)
B.if (previous - now >= interval)
C.if (now - previous >= interval)
D.if (now + interval > previous)
Correct Answer: if (now - previous >= interval)
Explanation:
Unsigned subtraction is defined modulo the counter range. When intervals are smaller than the wraparound period, now - previous >= interval remains correct across rollover.
Incorrect! Try again.
52An analog IR sensor produces 2.60 V, and the Arduino Uno uses its default 5.00 V analog reference. What ADC value is theoretically expected for the 10-bit converter?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Hard
A.About 858
B.About 133
C.About 512
D.About 532
Correct Answer: About 532
Explanation:
The ideal code is . Actual readings may differ because of reference tolerance, sensor output impedance, and ADC error.
Incorrect! Try again.
53A sensor's analog output has a source impedance of 200 k. Consecutive Arduino Uno ADC readings differ significantly, especially after switching from another channel. What is the best firmware-level correction?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Hard
A.Take one reading only and increase the serial baud rate
B.Discard the first conversion after channel selection and allow settling
C.Drive the analog pin HIGH before every conversion
D.Set all unused digital pins to INPUT without pull-ups
Correct Answer: Discard the first conversion after channel selection and allow settling
Explanation:
The ADC sample-and-hold capacitor needs adequate charging time through a high source impedance. A settling interval and discarded first conversion improve channel accuracy; buffering is the stronger hardware solution.
Incorrect! Try again.
54A binary IR sensor signal contains short noise pulses. The system must detect a genuine object only when at least 4 of the latest 5 samples are active. Which method implements this rule most directly?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Hard
A.Use a running five-sample window and count active samples
B.Average the samples as floating-point voltages only
C.Trigger whenever any two nonconsecutive samples are active
D.Accept the first active sample and reset the processor
Correct Answer: Use a running five-sample window and count active samples
Explanation:
A sliding window directly evaluates the stated majority criterion. It rejects isolated pulses while allowing a detection when the recent sample history contains at least four active values.
Incorrect! Try again.
55An IR sensor is connected to an Arduino Uno input located near a PWM motor-control wire. The detection fails only when the motor duty cycle changes rapidly. Which investigation should be performed first?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Hard
A.Replace digitalRead() with Serial.read()
B.Change the C++ variable names to shorter identifiers
C.Increase the number of LCD characters displayed
D.Check signal integrity, grounding, decoupling, and wire routing
Correct Answer: Check signal integrity, grounding, decoupling, and wire routing
Explanation:
The correlation with PWM transitions indicates conducted or radiated interference, ground bounce, or coupling. Oscilloscope measurements and wiring/power checks should precede software changes.
Incorrect! Try again.
56A sensor output is normally HIGH, but it becomes disconnected intermittently. The Arduino input then registers random transitions. Which configuration is most appropriate if the sensor interface is an open-collector output that asserts LOW?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Hard
A.Use a floating INPUT and average digital readings
B.Use INPUT_PULLUP and treat LOW as the active state
C.Use INPUT_PULLDOWN and treat HIGH as the active state
D.Use OUTPUT_LOW and read the same pin
Correct Answer: Use INPUT_PULLUP and treat LOW as the active state
Explanation:
An open-collector output can pull the line LOW but cannot drive it HIGH. A pull-up provides a defined inactive HIGH state, while LOW represents assertion.
Incorrect! Try again.
57An Arduino Uno drives an IR LED directly from a digital pin through a 100 resistor from a 5 V supply. The LED forward voltage is 1.2 V. Ignoring pin limits, the nominal current is approximately what value?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Hard
A.12 mA
B.24 mA
C.50 mA
D.38 mA
Correct Answer: 38 mA
Explanation:
The resistor-limited current is A, or approximately 38 mA. This may exceed the Arduino Uno pin's recommended operating current, so a transistor driver and a suitable resistor are preferable.
Incorrect! Try again.
58A reflective IR detector must distinguish sunlight from a nearby modulated IR emitter. Which receiver strategy gives the strongest rejection of steady ambient illumination?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Hard
A.Increase the receiver gain until the ADC saturates
B.Use a longer cable with no reference conductor
C.Measure only the total unmodulated photodiode current
D.Modulate the emitter and synchronously detect its modulation
Correct Answer: Modulate the emitter and synchronously detect its modulation
Explanation:
Synchronous detection identifies the emitter's known temporal pattern while rejecting steady background light. Saturation and unshielded wiring reduce, rather than improve, robustness.
Incorrect! Try again.
59A detection output drives a relay module from Arduino Uno pin D8. The relay resets the Arduino when energized. Which correction is most appropriate for a bare relay coil driven by a transistor?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Hard
A.Place a flyback diode across the coil and provide adequate supply decoupling
B.Remove the transistor so the pin absorbs the inductive transient
C.Use a capacitor across the sensor output instead of coil suppression
D.Connect the diode in series with the Arduino input pin
Correct Answer: Place a flyback diode across the coil and provide adequate supply decoupling
Explanation:
A relay coil generates a high-voltage transient when switched off. A correctly oriented flyback diode, transistor driver, common-ground design, and decoupling protect the Arduino from resets and voltage spikes.
Incorrect! Try again.
60A sensor is sampled every 10 ms, and a detection requires 5 consecutive active samples. An object enters the sensing region immediately after a sample. What is the worst-case confirmation latency, excluding sensor response time?
Design and implementation of an Arduino Uno and IR sensor-based detection system
Hard
A.40 ms
B.60 ms
C.10 ms
D.50 ms
Correct Answer: 50 ms
Explanation:
The first qualifying sample may arrive almost 10 ms after entry, followed by four more samples at 10 ms intervals. Thus confirmation can occur just under 50 ms after entry, conventionally specified as a 50 ms worst-case interval.
Incorrect! Try again.
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