Download Aptitude Crack
img not found img not found

Ohm''s Law - Engineering

Q1:

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

ANS:A - 9 V

V = I * R,
R = V/I.
R = 18/40*10^-3,
R = 18*1000/40,
R = 18000/40,
R = 450.
And now we Will the voltage dropps.

V = I*R.
V= 20*10^-3 * 450,
V= 20*450/1000,
V = 9000/1000,
V = 9v voltage dropped.