You are measuring the current in a circuit that is operated on an 18 V battery. The ammeter reads 40 mA. Later you notice the current has dropped to 20 mA. How much has the voltage changed?
A. 9 V
B. 900 mV
C. 0 V
D. 18 V
Answer: Option A
This Question Belongs to Electrical Engineering >> Ohms Law
R= 18/40mA =0.45 K ohm
V2= I 2 * R = 20mA * 0.45K ohm = 9 V