Arduino Quiz #2: Hardware

1. The circuit show below is used for questions 1-4:

A user has connected the circuits above. What is wrong with the circuit connected to pin D2?

There is no current limiting resistor for the LED.

Nothing is wrong.

The LED is inserted backwards.

Pin D2 may not be used to drive LEDs.

You should not use an orange wire to connect a red LED.

If you connected LEDs directly to Arduino pins without a current-limiting resistor, you risk drawing too much current from the pin, which could burn out either the LED or the Arduino pin (or both.)

Explanation

If you connected LEDs directly to Arduino pins without a current-limiting resistor, you risk drawing too much current from the pin, which could burn out either the LED or the Arduino pin (or both.)

2. The image below is used for several questions.

In the circuit shown above, what is the function of components R15 and R16?

Current Limiting Resistor.

Pull-up resistor.

Pull-down resistor.

None of the above

Components R15 and R16 in the circuit shown are functioning as current limiting resistors. These resistors are used to limit the amount of current flowing through the circuit, protecting other components from excessive current and potential damage.

Explanation

Components R15 and R16 in the circuit shown are functioning as current limiting resistors. These resistors are used to limit the amount of current flowing through the circuit, protecting other components from excessive current and potential damage.

3.

A user has wired up an Arduino Protoshield as shown above. Which of the schematics below match the wiring?

A

B

C

None of the above

not-available-via-ai

Explanation

not-available-via-ai

4. (This is the same image as before; it's repeated for better grouping with the questions)

In the image above, what is the function of R17?

Current limiting resistor

Pull-up resistor

Pull-down resistor

Light Sensor

None of the above

the arrows "shining" into R17 indicate that it is a resistor whose value changes depending on amount of illumination. With R19, it forms a voltage divider that provides a varying voltage to the analog input and can be used to measure light levels.

Explanation

the arrows "shining" into R17 indicate that it is a resistor whose value changes depending on amount of illumination. With R19, it forms a voltage divider that provides a varying voltage to the analog input and can be used to measure light levels.

5. Using the circuits show in Question 1, What is wrong with the circuits connected to pin D3?

The 5V output of an Arduino Uno is insufficient for a series connection of three LEDs

The resistor value is too high for this combination of LEDs.

The resistor value is too low for this combination of LEDs.

Nothing is wrong with the circuit.

None of the above

Each LED has a "voltage drop" of about 2V to 3V. When connected in series as show, those voltages add together, so the string of LEDs needs 6V or more to light up.

Explanation

Each LED has a "voltage drop" of about 2V to 3V. When connected in series as show, those voltages add together, so the string of LEDs needs 6V or more to light up.

6. In the image from the question above, what is the function of D8 and D9?

Kickback prevention diode

Indicator LED

Current limiting device

Light Sensor

None of the above

D8 and D9 are Light Emitting Diodes connected to digital output pins, presumably used as some sort of indicator.

Explanation

D8 and D9 are Light Emitting Diodes connected to digital output pins, presumably used as some sort of indicator.

7. In the image above, what is the function of D10?

Indicator LED

Kickback prevention diode

Pull-up resistor

Light sensor

None of the above

The coil of a relay has energy stored in its magnetic field. When you switch off the relay, this energy can create a voltage spike large enough to damage semiconductors. The kickback prevention diode limits this voltage to safe levels.

Explanation

The coil of a relay has energy stored in its magnetic field. When you switch off the relay, this energy can create a voltage spike large enough to damage semiconductors. The kickback prevention diode limits this voltage to safe levels.

8. Using the circuits show in Question 1: What is wrong with the circuits connected to pin D4?

The switch needs a pull-down resistor.

Pin D4 can not be used as a switch input.

Nothing is wrong with the circuit.

Switches should have a current limiting resistor.

None of the above

With the "other side" of the switch connected to +5V (as shown), the Arduino input will need a pull-down resistor in order to reliably read "0" when the switch is not pressed.
You could also connect the switch to ground, and use the internal pull-ups inside the AVR chip.

Explanation

With the "other side" of the switch connected to +5V (as shown), the Arduino input will need a pull-down resistor in order to reliably read "0" when the switch is not pressed.
You could also connect the switch to ground, and use the internal pull-ups inside the AVR chip.

9.

What is wrong with the circuit shown above? (check all that apply)

The LED is inserted backwards.

The Arduino cannot operate from a 9V battery.

The resistor value is wrong.

The Arduino is unpowered because the protoboard power rails are not fully connected.

Pin D8 can not be used to drive an LED.

The LED is inserted backwards because the longer leg of the LED (anode) should be connected to the positive side of the circuit. The Arduino is unpowered because the protoboard power rails are not fully connected, meaning that there is no power supply reaching the Arduino.

Explanation

The LED is inserted backwards because the longer leg of the LED (anode) should be connected to the positive side of the circuit. The Arduino is unpowered because the protoboard power rails are not fully connected, meaning that there is no power supply reaching the Arduino.

Submit

10. Using the circuits show in Question 1 What is wrong with the circuits connected to pin D5?

The LED is shorted out.

The current-limited resistor for the LED has the wrong value.

Pin D5 should be reserved for Serial

Nothing is wrong with the circuit.

None of the above

The columns of a prototype board are connected to each other, so both sides of the LED are essentially connected to the same wire - ie "short circuited."

Explanation

The columns of a prototype board are connected to each other, so both sides of the LED are essentially connected to the same wire - ie "short circuited."

11. In the image above, what is the function of R14?

Current limiting resistor

Pull-up resistor

Pull-down resistor

Light sensor

None of the above

R14 is a resistor that limits the current as the MOSFET gate capacitance charges and discharges.
For relatively small MOSFETs, it may not be necessary.

Explanation

R14 is a resistor that limits the current as the MOSFET gate capacitance charges and discharges.
For relatively small MOSFETs, it may not be necessary.