Solutions

Ohm’s Law: Solutions

Questions

1. Answer: It solves for voltage, assuming current and resistance are known.
2. Answer:  You can calculate current with I = V / R
3. Answer: A
4. Answer: Divide both sides of the equation by I.

Exercises

1. Answer: V = I x R → V / R = (I x R) / R → I = V / R
2. Answer: I = V / R = 1.3 / 2000 = 0.00065 A = 0.65 mA or 650 µA
3. Answer: R = V / I = 3.3 V  / 0.001 A = 3000 Ω = 3.3 kΩ

Project

Solution:  The result of I needs to be multiplied by 1000 before it is displayed, and the A unit needs to be updated to mA.  Retest the numbers in the activity, and verify that the results are 5.4545… mA and 1.2 mA.

# calculate_i_in_ma_from_v_and_r

from microbit import *

while True:
    text = input("Enter volts: ")
    V = float(text)
    text = input("Enter ohms: ")
    R = float(text)
    
    I = V / R
    I = I * 1000                   # <-- Add
    
    print("I = ", I, "mA")         # <-- Modify
    print()