Answer:
Quantity of charge = 36 Coulombs.
Explanation:
Given the following data;
Current = 20 mA = 20/1000 = 0.02 Amperes
Time, t = 30 minutes to seconds = 30 * 60 = 1800 seconds
To find the quantity of charge;
Quantity of charge = current * time
Quantity of charge = 0.02 * 1800
Quantity of charge = 36 Coulombs.