I understand your problem, bluemoon, we are very close by on the academic ladder. I'm telling you all this because even I wanna revise
Ohm's law is like:
V=IR
V is the potential difference across the resistor
I is the current flowing through th resistor
R is the resistance.
So lets solve your first question
Quote:
|
An Electric DC Circuit is attached to a 12-volt batter and has a 3-ohm resistor in it.Find the current flowing through the circuit
|
V= 12 Volts
R= 3 Ohms
So 12=(I)3
giving I= 4 Amperes
Now your second one
Quote:
|
What is the current in an AC Circuit with 120 volts and a 60 watt light bulb?
|
Remember that the bulb is using 60 watts when you supply 120 volts.
So
its using 60 Joules used per second.
Use the equations: P=(V^2)/R
(means V squared divided by R) and P=(I^2)R
The symbols have the usual significance.
So, P=60 Joules per second
V= 120 Volts
We get 60=120*120/R
Solving, R=240 Ohms
Now we can use this in the second equation I mentioned.
60=(I^2)240
I^2=1/4
I=1/2 = 0.5 Amperes
Thats all! So simple for theory.
Want a tip to excel in your exams?
Won't you bother to read your textbooks to get the concepts? No hope for you if you don't...