Computing resistor power dissipation in Python using UliEngineering

In this example we’ll calculate the power dissipation of a 1 kΩ resistor with a constant current of 30 mA flowing through it, using our science and engineering Python library UliEngineering.

In order to install UliEngineering (a Python3-only library), run

sudo pip3 install -U UliEngineering

Now we can compute the resistor power dissipation using power_dissipated_in_resistor_by_current()

from UliEngineering.EngineerIO import auto_print
from UliEngineering.Electronics.Resistors import *
# Just compute the value:
power = power_dissipated_in_resistor_by_current("1 kΩ", "30 mA") # power = 0.9

# Print value: prints: prints "900 mW"
auto_print(power_dissipated_in_resistor_by_current, "1 kΩ", "30 mA")

Since the result is 900 mW, you can deduce that you need to use a resistor with a power rating of at least one Watt.

Note that you can pass both numbers (like 0.03) or strings (like 30 mA or 0.03 A) to most UliEngineering functions. SI prefixes like k and M are automatically decoded

If you know the voltage across the resistor, you can use power_dissipated_in_resistor_by_voltage(). Let’s assume there is 1V dropped across the resistor:

from UliEngineering.EngineerIO import auto_print
from UliEngineering.Electronics.Resistors import *
# Just compute the value:
power = power_dissipated_in_resistor_by_voltage("1 kΩ", "30 mA") # power = 0.001

# Print value: prints: prints "1.00 mW"
auto_print(power_dissipated_in_resistor_by_voltage, "1 kΩ", "30 mA")

So in this case the power dissipation is extremely low - only 1.00 mW - and won’t matter for most practical applications.

In many cases, you can also pass NumPy arrays to UliEngineering functions:

from UliEngineering.EngineerIO import format_value
from UliEngineering.Electronics.Resistors import *
import numpy as np

# Compute the value:
resistors = np.asarray([100, 500, 1000]) # 100 Ω, 500 Ω, 1 kΩ
power = power_dissipated_in_resistor_by_voltage(resistors, "30 mA") # power = 0.001

# power = [9.0e-06 1.8e-06 9.0e-07]