DuckieDai Coulomb's Law Python Program

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physics · MIT License

Overview

Solve electric force, either charge magnitude, or separation distance using Coulomb's law and identify attraction or repulsion when charge signs are known.

Usage

Inputs

Requested unknown: electric force, charge 1, charge 2, or distance
Known charges in coulombs and distance in metres

Outputs

Requested value and, when both charge signs are supplied, attractive or repulsive force type

Units: Charges use coulombs, distance uses metres, and force uses newtons.

Assumptions and limitations

Assumptions

Charges are treated as point charges and ke is 8.988E9.

Constraints

Distance and force magnitudes must be positive; divisor values cannot be zero.

Known failures

Force magnitude alone cannot determine an unknown charge's sign.
Inconsistent units produce an incorrect result.

Compatibility and review

Review status: Tested on a TI calculator
Tested on: TI-84 Plus CE Python; OS 5.8.3; Python App 5.8.3.0048; exact paginated .py transferred through TI Connect CE into RAM and tested individually
What happened: Passed: branded intro, paginated menu, Coulomb law workflow, force type output, and answer screen ran on the physical calculator
Dependencies: math
Suggested calculator name: COULOMB — you can give it another valid, unique name when you transfer it
Desktop test cases: Not available for this interactive-only source

This exact source auto-launches an interactive calculator session, so compatibility evidence comes from the recorded physical-device review rather than an importable desktop fixture.

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Exact reviewed bytes

Source code

Download .py

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"""DuckieDai Coulomb's Law for TI-84 Plus CE Python."""

from math import sqrt


def duckiedai_intro(program_name, wait=True):
    """Show the reusable DuckieDai program opening."""
    title = program_name[:16]
    empty = 16 - len(title)
    left = empty // 2
    right = empty - left

    print("+----------------------+")
    print("|   " + " " * left + title + " " * right + "   |")
    print("|                      |")
    print("|       __             |")
    print("|   ___(o )>  quack!   |")
    print("|   \\ <_. )           |")
    print("|    `---'             |")
    print("|     by DuckieDai     |")
    print("+----------------------+")
    print("Loading...")

    if wait:
        input("Press enter to start ")
        print("\n" * 6)


def number(prompt):
    """Allow positive or negative finite numbers."""
    while True:
        try:
            value = float(input(prompt))

            if value > -1e100 and value < 1e100:
                return value

        except ValueError:
            pass

        print("Enter a valid number.")


def nonzero_number(prompt):
    """Require a number other than zero."""
    while True:
        value = number(prompt)

        if value != 0:
            return value

        print("Value cannot be zero.")


def positive_number(prompt):
    """Require a number greater than zero."""
    while True:
        try:
            value = float(input(prompt))

            if value > 0 and value < 1e100:
                return value

        except ValueError:
            pass

        print("Enter a number above 0.")


def show_answer(name, value, unit):
    input("Press enter for answer ")
    print("\n" * 6)
    print("ANSWER")
    print(name + " = " + str(value))
    print(unit)


def force_type(q1, q2):
    """Tell whether two charges attract or repel."""
    if q1 * q2 < 0:
        return "ATTRACTIVE"
    else:
        return "REPULSIVE"


def main():
    duckiedai_intro("COULOMBS LAW")

    ke = 8.988e9

    print("COULOMB'S LAW")
    print()
    print("Formula:")
    print("Fe = ke*|q1*q2|/r^2")
    print()
    print("ke = 8.988E9")
    input("Press enter for menu ")
    print("\n" * 6)
    print()
    print("What do you need?")
    print()
    print("1. Electric force")
    print("2. Charge 1")
    print("3. Charge 2")
    print("4. Distance")
    print()

    choice = input("Choose 1-4: ")

    print()

    # ==========================================
    # 1. SOLVE ELECTRIC FORCE
    #
    # Fe = ke*|q1*q2|/r^2
    # ==========================================

    if choice == "1":

        q1 = nonzero_number("Charge 1 (C): ")
        q2 = nonzero_number("Charge 2 (C): ")
        r = positive_number("Distance (m): ")

        force = (
            ke * abs(q1 * q2) /
            (r ** 2)
        )

        print()
        print("Using:")
        print("Fe = ke*|q1*q2|/r^2")

        show_answer(
            "Fe",
            force,
            "newtons"
        )

        print()
        print("Force type:")
        print(force_type(q1, q2))

    # ==========================================
    # 2. SOLVE MAGNITUDE OF CHARGE 1
    #
    # |q1| = Fe*r^2 / (ke*|q2|)
    # ==========================================

    elif choice == "2":

        force = positive_number("Force (N): ")
        q2 = nonzero_number("Charge 2 (C): ")
        r = positive_number("Distance (m): ")

        q1 = (
            force * r ** 2 /
            (ke * abs(q2))
        )

        print()
        print("Using:")
        print("Fe = ke*|q1*q2|/r^2")
        print()
        print("Rearranged:")
        print("|q1| = Fe*r^2")
        print("       /(ke*|q2|)")

        show_answer(
            "|q1|",
            q1,
            "coulombs"
        )

        print()
        print("Note:")
        print("Force alone cannot")
        print("determine q1 sign.")

    # ==========================================
    # 3. SOLVE MAGNITUDE OF CHARGE 2
    #
    # |q2| = Fe*r^2 / (ke*|q1|)
    # ==========================================

    elif choice == "3":

        force = positive_number("Force (N): ")
        q1 = nonzero_number("Charge 1 (C): ")
        r = positive_number("Distance (m): ")

        q2 = (
            force * r ** 2 /
            (ke * abs(q1))
        )

        print()
        print("Using:")
        print("Fe = ke*|q1*q2|/r^2")
        print()
        print("Rearranged:")
        print("|q2| = Fe*r^2")
        print("       /(ke*|q1|)")

        show_answer(
            "|q2|",
            q2,
            "coulombs"
        )

        print()
        print("Note:")
        print("Force alone cannot")
        print("determine q2 sign.")

    # ==========================================
    # 4. SOLVE DISTANCE
    #
    # r = sqrt(ke*|q1*q2|/Fe)
    # ==========================================

    elif choice == "4":

        force = positive_number("Force (N): ")
        q1 = nonzero_number("Charge 1 (C): ")
        q2 = nonzero_number("Charge 2 (C): ")

        r = sqrt(
            ke * abs(q1 * q2) /
            force
        )

        print()
        print("Using:")
        print("Fe = ke*|q1*q2|/r^2")
        print()
        print("Rearranged:")
        print("r = sqrt(")
        print("ke*|q1*q2|/Fe)")

        show_answer(
            "r",
            r,
            "meters"
        )

        print()
        print("Force type:")
        print(force_type(q1, q2))

    else:
        print("Invalid choice.")

    print()
    print("DuckieDai says: done!")


# TI-Python imports the selected AppVar rather than
# setting __name__ to main.
main()

"""DuckieDai Coulomb's Law for TI-84 Plus CE Python."""
from math import sqrt
def duckiedai_intro(program_name, wait=True):
"""Show the reusable DuckieDai program opening."""
title = program_name[:16]
empty = 16 - len(title)
left = empty // 2
right = empty - left
print("+----------------------+")
print("| " + " " * left + title + " " * right + " |")
print("| |")
print("| __ |")
print("| ___(o )> quack! |")
print("| \\ <_. ) |")
print("| `---' |")
print("| by DuckieDai |")
print("+----------------------+")
print("Loading...")
if wait:
input("Press enter to start ")
print("\n" * 6)
def number(prompt):
"""Allow positive or negative finite numbers."""
while True:
try:
value = float(input(prompt))
if value > -1e100 and value < 1e100:
return value
except ValueError:
pass
print("Enter a valid number.")
def nonzero_number(prompt):
"""Require a number other than zero."""
while True:
value = number(prompt)
if value != 0:
return value
print("Value cannot be zero.")
def positive_number(prompt):
"""Require a number greater than zero."""
while True:
try:
value = float(input(prompt))
if value > 0 and value < 1e100:
return value
except ValueError:
pass
print("Enter a number above 0.")
def show_answer(name, value, unit):
input("Press enter for answer ")
print("\n" * 6)
print("ANSWER")
print(name + " = " + str(value))
print(unit)
def force_type(q1, q2):
"""Tell whether two charges attract or repel."""
if q1 * q2 < 0:
return "ATTRACTIVE"
else:
return "REPULSIVE"
def main():
duckiedai_intro("COULOMBS LAW")
ke = 8.988e9
print("COULOMB'S LAW")
print()
print("Formula:")
print("Fe = ke*|q1*q2|/r^2")
print()
print("ke = 8.988E9")
input("Press enter for menu ")
print("\n" * 6)
print()
print("What do you need?")
print()
print("1. Electric force")
print("2. Charge 1")
print("3. Charge 2")
print("4. Distance")
print()
choice = input("Choose 1-4: ")
print()
# ==========================================
# 1. SOLVE ELECTRIC FORCE
#
# Fe = ke*|q1*q2|/r^2
# ==========================================
if choice == "1":
q1 = nonzero_number("Charge 1 (C): ")
q2 = nonzero_number("Charge 2 (C): ")
r = positive_number("Distance (m): ")
force = (
ke * abs(q1 * q2) /
(r ** 2)
)
print()
print("Using:")
print("Fe = ke*|q1*q2|/r^2")
show_answer(
"Fe",
force,
"newtons"
)
print()
print("Force type:")
print(force_type(q1, q2))
# ==========================================
# 2. SOLVE MAGNITUDE OF CHARGE 1
#
# |q1| = Fe*r^2 / (ke*|q2|)
# ==========================================
elif choice == "2":
force = positive_number("Force (N): ")
q2 = nonzero_number("Charge 2 (C): ")
r = positive_number("Distance (m): ")
q1 = (
force * r ** 2 /
(ke * abs(q2))
)
print()
print("Using:")
print("Fe = ke*|q1*q2|/r^2")
print()
print("Rearranged:")
print("|q1| = Fe*r^2")
print(" /(ke*|q2|)")
show_answer(
"|q1|",
q1,
"coulombs"
)
print()
print("Note:")
print("Force alone cannot")
print("determine q1 sign.")
# ==========================================
# 3. SOLVE MAGNITUDE OF CHARGE 2
#
# |q2| = Fe*r^2 / (ke*|q1|)
# ==========================================
elif choice == "3":
force = positive_number("Force (N): ")
q1 = nonzero_number("Charge 1 (C): ")
r = positive_number("Distance (m): ")
q2 = (
force * r ** 2 /
(ke * abs(q1))
)
print()
print("Using:")
print("Fe = ke*|q1*q2|/r^2")
print()
print("Rearranged:")
print("|q2| = Fe*r^2")
print(" /(ke*|q1|)")
show_answer(
"|q2|",
q2,
"coulombs"
)
print()
print("Note:")
print("Force alone cannot")
print("determine q2 sign.")
# ==========================================
# 4. SOLVE DISTANCE
#
# r = sqrt(ke*|q1*q2|/Fe)
# ==========================================
elif choice == "4":
force = positive_number("Force (N): ")
q1 = nonzero_number("Charge 1 (C): ")
q2 = nonzero_number("Charge 2 (C): ")
r = sqrt(
ke * abs(q1 * q2) /
force
)
print()
print("Using:")
print("Fe = ke*|q1*q2|/r^2")
print()
print("Rearranged:")
print("r = sqrt(")
print("ke*|q1*q2|/Fe)")
show_answer(
"r",
r,
"meters"
)
print()
print("Force type:")
print(force_type(q1, q2))
else:
print("Invalid choice.")
print()
print("DuckieDai says: done!")
# TI-Python imports the selected AppVar rather than
# setting __name__ to main.
main()

Filename: COULOMB.py
Size: 5856 bytes
SHA-256: b569e112c44626a91e96f49630b52a1821bb5f1f996fc577b7c7a3e76eb47c2c

Transfer and launch

Confirm that your calculator is the Python-capable model named above. Check that its OS and Python App versions match the reviewed record.
Download the .py source above and verify its SHA-256 digest if your computer provides that option.
Use TI Connect CE to send the Python file to a compatible calculator. COULOMB is a suggested name; you may choose another valid, unique calculator name.
Open the Python App, select the program, and check sample inputs before relying on other results.

Read the complete installation, launch, troubleshooting, and removal guide.

Availability does not mean a teacher, school, or exam permits this program. Follow the applicable rules.

Version history

1.0.0 — current version, published 2026-09-23. Download this reviewed version

Any source change requires a new immutable version and digest. Historical downloads remain available only while their review records remain valid.

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