Three lamps with 20, 30, and 40 ohms of resistance are conected in parallel to a 120 volt circuit. What current flows through each lamp? Would it be 1 1/3?

 

Nope.

Since the resistors are in parallel they will all see the same voltage across them. With this in mind, you can apply Ohms Law on each resistor and determine the current flowing in each one individually.

hgmjr

 

Knowing the Law for voltage across resistors in parallel, and knowing Ohm's Law, you can solve for current through each resistor.

 

an additional info:
the total current provided by the voltage source is the addition of the
currents thru individual circuits which u'll find out by application of ohms law
for each lamp separately as stated already by mr thingmaker and mr hgmjr

this total current can also be found out by finding equivalent resistance of parallel resistance combination.
the current in individual paths can thus also be found using the current distribution formula (if u solve circuits with different approach ,u'll learn a lot abt ckts and have a good understanding of them )