Three light bulbs in parallel circuit and Currents

Click For Summary
SUMMARY

In a parallel circuit with three light bulbs, removing one bulb results in an increase in overall resistance, leading to a decrease in total current. Initially, with three bulbs of 2 ohms each connected to a 3V battery, the total resistance is 1.5 ohms, yielding a current of 2 Amps. When one bulb is removed, the resistance becomes 1.0 ohm, resulting in a current of 3 Amps. However, the confusion arises from misapplying the formula for total resistance in parallel circuits, which is R = 1/(1/R1 + 1/R2 + ...).

PREREQUISITES
  • Understanding of Ohm's Law (I = V/R)
  • Knowledge of parallel circuit configurations
  • Familiarity with calculating total resistance in parallel circuits
  • Basic electrical concepts such as voltage and current
NEXT STEPS
  • Study the principles of parallel circuits in depth
  • Learn how to calculate total resistance for multiple resistors in parallel
  • Explore the effects of adding or removing components in electrical circuits
  • Review practical applications of Ohm's Law in circuit analysis
USEFUL FOR

Students studying electrical engineering, educators teaching circuit theory, and anyone interested in understanding the behavior of electrical circuits involving parallel configurations.

kfreshn
Messages
5
Reaction score
0

Homework Statement



Pretend you have three light bulbs in a parallel circuit and one light bulb goes out/removed so that there two light bulbs remaining.

Does current of the entire circuit increase, remain same, or decrease after the one of the bulb is removed.

The answer is decrease.

I thought it would have increased.
i'm slightly confused here, doesn't the current in the overall circuit increase since the resistance of the circuit has decreased if you remove one light bulb.

Afterall, I (of circuit) = V/R. When one light bulb(resistor) is removed from a parallel circuit, the overall Resistance of the circuit decreases and the Voltage remains the same,thus shouldn't the current of the circuit increase?

Lets say each light bulb resistance is 2 ohms. And battery is 3V.

At first with all 3 connected: for resistors connected in parallel its 1/2+1/2+1/2 = 1.5
Thus, I=V/R --> 3/1.5 = 2 Amps.
When one light bulb is removed, the overall resistance is 1/2 + 1/2 = 1.0
Thus, I=V/R --> 3/1.0 = 3 Amps.

Thats how i logically and mathematically reason the answer should have been the overall current in the parallel circuit increases when one of the three light bulb burns out or is removed.

All help is appreciated.
 
Physics news on Phys.org
kfreshn said:
i'm slightly confused here, doesn't the current in the overall circuit increase since the resistance of the circuit has decreased if you remove one light bulb.

Well, if the resistance decreased, then the currently certainly WOULD go up, but since the resistance increases, the current goes down.

You need to study parallel circuits.
 
phinds said:
Well, if the resistance decreased, then the currently certainly WOULD go up, but since the resistance increases, the current goes down.

You need to study parallel circuits.

Oh thank you very much. I rechecked and it was 1/R=(1/R1)+(1/R2)+... etc

I miswrote my formula was R=(1/R1)+(1/R2)+...etc

Thank you very much for your time and help!
 

Similar threads

Replies
4
Views
2K
  • · Replies 6 ·
Replies
6
Views
1K
Replies
6
Views
2K
  • · Replies 9 ·
Replies
9
Views
1K
Replies
4
Views
2K
Replies
1
Views
3K
Replies
5
Views
2K
  • · Replies 10 ·
Replies
10
Views
915
  • · Replies 14 ·
Replies
14
Views
1K
  • · Replies 2 ·
Replies
2
Views
4K