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Unit 2 - Practice Quiz

ECE249

1 Which of the following statements best describes an Analog Signal?

A. A discrete signal representing binary data
B. A continuous signal that represents physical measurements
C. A signal that has only two states: HIGH and LOW
D. A signal used exclusively for USB communication

2 What is the primary characteristic of a Digital Signal?

A. It varies continuously over time
B. It takes on infinite values within a range
C. It represents data as a sequence of discrete values (0s and 1s)
D. It is always a sine wave

3 Which microcontroller is used on the standard Arduino Uno R3 board?

A. ATmega2560
B. ATmega328P
C. ATtiny85
D. ESP8266

4 How many digital I/O pins are available on the Arduino Uno board?

A. 6
B. 10
C. 14
D. 20

5 How many of the digital pins on the Arduino Uno provide PWM (Pulse Width Modulation) output?

A. 14
B. 6
C. 2
D. 8

6 Which pins on the Arduino Uno are used for UART serial communication?

A. Pins A0 and A1
B. Pins 11 and 12
C. Pins 0 (RX) and 1 (TX)
D. Pins 3 and 5

7 What is the operating voltage of the ATmega328P on a standard Arduino Uno?

A. 3.3V
B. 5V
C. 9V
D. 12V

8 Which pin allows you to supply an external voltage to the Arduino board (typically 7-12V)?

A. 5V
B. 3.3V
C. Vin
D. AREF

9 What is the function of the ADC (Analog-to-Digital Converter) in the Arduino?

A. To convert digital code into analog voltage
B. To convert continuous analog voltage into a digital number
C. To amplify the current
D. To reset the board

10 The Arduino Uno has a 10-bit ADC. What is the range of digital values it can produce?

A. 0 to 255
B. 0 to 511
C. 0 to 1023
D. 0 to 4095

11 Which built-in LED is connected to digital pin 13 on the Arduino Uno?

A. TX LED
B. RX LED
C. L (User LED)
D. Power LED

12 What does PWM stand for in the context of Arduino pins?

A. Power Wave Management
B. Pulse Width Modulation
C. Pin Wire Mode
D. Phase Width Measurement

13 Which Arduino pin is used to set the reference voltage for analog inputs?

A. IOREF
B. AREF
C. RESET
D. GND

14 What is the recommended maximum DC current per I/O pin on the Arduino Uno?

A. 20 mA
B. 100 mA
C. 500 mA
D. 1 A

15 Which component on the Arduino board ensures the voltage does not exceed 5V when powered via the DC jack?

A. Crystal Oscillator
B. USB Controller
C. Voltage Regulator
D. Reset Button

16 What is the frequency of the crystal oscillator on the Arduino Uno?

A. 8 MHz
B. 16 MHz
C. 20 MHz
D. 1 GHz

17 What is an IR Sensor primarily used to detect?

A. Sound waves
B. Humidity
C. Obstacles or motion via infrared light
D. Magnetic fields

18 Which component acts as the transmitter in an IR sensor module?

A. Photodiode
B. IR LED
C. Potentiometer
D. Op-Amp

19 Which component acts as the receiver in an active IR sensor module?

A. IR LED
B. Photodiode
C. Resistor
D. Capacitor

20 What is the function of the potentiometer on a digital IR obstacle avoidance sensor module?

A. To change the emitted light color
B. To adjust the detection distance/sensitivity
C. To turn the sensor on and off
D. To regulate voltage to 3.3V

21 Why can humans generally not see the light emitted by an IR sensor?

A. It is too bright
B. It is too dim
C. Its wavelength is outside the visible spectrum
D. It is blocked by the air

22 Which component is often used as a comparator in IR sensor modules to provide a digital output?

A. LM358 or LM393
B. NE555
C. 7805
D. ATmega328

23 What does LDR stand for?

A. Light Detecting Relay
B. Light Dependent Resistor
C. Long Distance Resistor
D. Low Density Resistance

24 What is the working principle of an LDR?

A. Piezoelectric effect
B. Photovoltaic effect
C. Photoconductivity
D. Hall effect

25 How does the resistance of an LDR change with light intensity?

A. Resistance increases as light intensity increases
B. Resistance decreases as light intensity increases
C. Resistance remains constant
D. Resistance becomes zero instantly

26 Which material is commonly used to manufacture LDRs?

A. Silicon
B. Cadmium Sulfide (CdS)
C. Copper
D. Aluminum

27 In a voltage divider circuit with a fixed resistor and an LDR, if the LDR is connected to ground, what happens to the output voltage when light intensity increases?

A. The voltage increases
B. The voltage decreases
C. The voltage stays at 5V
D. The voltage becomes negative

28 What is the typical resistance of an LDR in total darkness?

A. Zero ohms
B. A few ohms
C. Several Mega-ohms
D. Negative resistance

29 Which sensor is commonly used to measure distance using sound waves?

A. PIR Sensor
B. Ultrasonic Sensor (HC-SR04)
C. LDR
D. DHT11

30 What is the typical frequency of the sound waves emitted by the HC-SR04 ultrasonic sensor?

A. 20 Hz
B. 1 kHz
C. 40 kHz
D. 1 MHz

31 What is the function of the Trig (Trigger) pin on the HC-SR04 sensor?

A. It receives the reflected sound wave
B. It powers the sensor
C. It initiates the measurement by sending a pulse
D. It connects to Ground

32 What is the function of the Echo pin on the HC-SR04 sensor?

A. It emits the sound wave
B. It outputs a high pulse with duration proportional to the distance
C. It adjusts the sensitivity
D. It provides the 5V power

33 The formula to calculate distance () using an ultrasonic sensor, where is the echo time and is the speed of sound, is:

A.
B.
C.
D.

34 If the speed of sound is approximately 340 m/s, how many microseconds does it take to travel 1 cm (there and back)?

A. ~29 microseconds
B. ~58 microseconds
C. ~100 microseconds
D. ~10 microseconds

35 What is a limitation of the ultrasonic sensor?

A. It cannot measure in the dark
B. It has a 'blind zone' very close to the sensor (e.g., < 2cm)
C. It requires a magnet to work
D. It only works in a vacuum

36 Can an ultrasonic sensor work in a vacuum?

A. Yes, perfectly
B. No, sound waves require a medium to travel
C. Yes, but with reduced range
D. Only if the object is metal

37 What do the DHT11 and DHT22 sensors measure?

A. Distance and Time
B. Light and Color
C. Temperature and Humidity
D. Pressure and Altitude

38 Between DHT11 and DHT22, which one generally provides higher accuracy and a wider range?

A. DHT11
B. DHT22
C. Both are identical
D. Neither works with Arduino

39 What type of data signal does the DHT11 sensor output?

A. Continuous Analog Voltage
B. Single-wire Digital Signal
C. I2C Protocol
D. SPI Protocol

40 What is the typical sampling interval (minimum time between readings) for a DHT11 sensor?

A. 1 microsecond
B. 1 millisecond
C. 1 second
D. 10 seconds

41 Which sensing element is used inside a DHT sensor to measure moisture?

A. Photodiode
B. Capacitive humidity sensor
C. Strain gauge
D. Piezo element

42 When wiring a DHT sensor, a resistor is often placed between VCC and the Data pin. What is this resistor called?

A. Pull-down resistor
B. Pull-up resistor
C. Current limiting resistor
D. Shunt resistor

43 The temperature range of the DHT11 is approximately:

A. -50°C to 150°C
B. 0°C to 50°C
C. 100°C to 200°C
D. Absolute Zero

44 To read data from a DHT11 using Arduino, which library is commonly used?

A. Servo.h
B. LiquidCrystal.h
C. DHT.h
D. SPI.h

45 If an analog sensor is connected to pin A0, which Arduino function is used to read the value?

A. digitalRead(A0)
B. analogRead(A0)
C. analogWrite(A0)
D. Serial.read(A0)

46 What is the return type and range of the digitalRead() function?

A. Integer (0 to 1023)
B. Float (0.0 to 5.0)
C. Integer (HIGH or LOW)
D. String ("ON" or "OFF")

47 Which Arduino function is used to configure a pin as an Input or Output?

A. pinMode()
B. digitalWrite()
C. setupPin()
D. configIO()

48 What happens if you supply 5V to an Analog Input pin on Arduino?

A. The board resets
B. analogRead() returns 0
C. analogRead() returns 1023
D. The pin burns out

49 The command analogWrite() is used for which specific functionality?

A. Reading analog voltages
B. Writing to EEPROM
C. Generating PWM signals
D. Serial communication

50 What is the resolution of the analogWrite() function (PWM resolution) on an Arduino Uno?

A. 8-bit (0-255)
B. 10-bit (0-1023)
C. 12-bit (0-4095)
D. 16-bit (0-65535)