Automated plant watering system in Raspberry Pi - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this soil moisture check?

Consider this Python code snippet that reads a soil moisture sensor value and decides whether to water the plant.

moisture = 350
if moisture < 300:
    print("Watering plant")
else:
    print("Soil is moist enough")

What will this code print?

Raspberry Pi

moisture = 350
if moisture < 300:
    print("Watering plant")
else:
    print("Soil is moist enough")

A Soil is moist enough

B Error: moisture sensor not found

C No output

D Watering plant

💡 Hint

Think about the condition: is 350 less than 300?

The moisture value is 350, which is not less than 300, so the else block runs, printing "Soil is moist enough".

❓ Predict Output

intermediate

What does this pump control code print?

This code controls a water pump based on a boolean variable pump_on. What is the output?

pump_on = False
if pump_on:
    print("Pump is running")
else:
    print("Pump is off")

Raspberry Pi

pump_on = False
if pump_on:
    print("Pump is running")
else:
    print("Pump is off")

A Pump status unknown

B Pump is running

C Pump is off

D Error: pump_on not defined

💡 Hint

Remember that False means the condition is not true.

Since pump_on is False, the else block runs and prints "Pump is off".

🔧 Debug

advanced

Why does this watering loop run forever?

Look at this code snippet that should water the plant once when soil is dry, but it keeps watering endlessly. What is the cause?

while True:
    moisture = 250
    if moisture < 300:
        print("Watering plant")
    else:
        print("Soil is moist enough")

Raspberry Pi

while True:
    moisture = 250
    if moisture < 300:
        print("Watering plant")
    else:
        print("Soil is moist enough")

A The else block is missing a break statement

B The moisture value never changes inside the loop

C The print statement causes the loop to restart

D The loop condition is wrong, should be while moisture < 300

💡 Hint

Think about what happens to the moisture value each time the loop runs.

The moisture value is always set to 250 inside the loop, so the condition moisture < 300 is always true, causing infinite watering.

📝 Syntax

advanced

Which option has correct syntax to read sensor and water plant?

Choose the code snippet that correctly reads a moisture sensor and waters the plant if dry.

A

moisture = read_sensor()
if moisture < 300:
    water_plant()

B

moisture = read_sensor()
if moisture < 300
    water_plant()

C

moisture = read_sensor()
if moisture < 300:
water_plant()

D

moisture = read_sensor()
if moisture < 300:
    water_plant

💡 Hint

Remember Python needs a colon and indentation for blocks.

Option A has the correct colon after the if statement and indented block for water_plant().

🚀 Application

expert

How many times will the pump run in this code?

This code runs a watering pump based on sensor readings in a list. How many times will it print "Pump running"?

moisture_readings = [320, 280, 290, 310, 270]
pump_runs = 0
for moisture in moisture_readings:
    if moisture < 300:
        print("Pump running")
        pump_runs += 1
print(pump_runs)

Raspberry Pi

moisture_readings = [320, 280, 290, 310, 270]
pump_runs = 0
for moisture in moisture_readings:
    if moisture < 300:
        print("Pump running")
        pump_runs += 1
print(pump_runs)

A 4

B 2

C 5

D 3

💡 Hint

Count how many values in the list are less than 300.

The values 280, 290, and 270 are less than 300, so the pump runs 3 times.