Light Bulbs in a parallel circuit


by chemistrykid
Tags: bulbs, circuit, light, parallel
chemistrykid
chemistrykid is offline
#1
Jan25-06, 02:57 PM
P: 2
Q: Two bulbs x and y are connected in parallel to a new dry cell. The switch is closed. If bulb x is unscrewed, the brightness of bulb y will
a) double
b) halve
c) remain the same
d) become 0

A: a? The current from the first branch would go into the second branch?
Phys.Org News Partner Science news on Phys.org
SensaBubble: It's a bubble, but not as we know it (w/ video)
The hemihelix: Scientists discover a new shape using rubber bands (w/ video)
Microbes provide insights into evolution of human language
Astronuc
Astronuc is offline
#2
Jan26-06, 09:40 AM
Admin
Astronuc's Avatar
P: 21,637
Quote Quote by chemistrykid
Q: Two bulbs x and y are connected in parallel to a new dry cell. The switch is closed. If bulb x is unscrewed, the brightness of bulb y will
a) double
b) halve
c) remain the same
d) become 0

A: a? The current from the first branch would go into the second branch?
The voltage remains the same. What happens when bulb is removed? Think about the resistance of each bulb, and the relationship between voltage, current and resistance.
berkeman
berkeman is offline
#3
Jan26-06, 10:39 AM
Mentor
berkeman's Avatar
P: 39,708
Quote Quote by chemistrykid
Q: Two bulbs x and y are connected in parallel to a new dry cell. The switch is closed. If bulb x is unscrewed, the brightness of bulb y will
a) double
b) halve
c) remain the same
d) become 0

A: a? The current from the first branch would go into the second branch?
It depends on the battery chemistry. But as with many subtle multiple-choice questions, there is only one best answer in the choices given (as Astro has indicated).

In the real world, however, batteries have a finite output impedance, so even a new battery's output voltage will droop some as it is loaded more. So the output voltage will be a bit less when it is outputting twice the current (to drive both bulbs). So if there were an answer e) that said "increase slightly", that would be the correct choice. Since that isn't listed, what is the next best choice?

tony873004
tony873004 is offline
#4
Jan26-06, 01:23 PM
Sci Advisor
PF Gold
P: 1,542

Light Bulbs in a parallel circuit


The light bulbs in your home are wired in parallel. If you unscrew one, how does it affect the others?


Register to reply

Related Discussions
HELP! Light bulbs and circuits! Introductory Physics Homework 10
3 light bulbs 3 switches Brain Teasers 9
Light bulbs in parallel and series Introductory Physics Homework 2
65W bulbs connected in parallel... (hopefully easy) Introductory Physics Homework 4
Light bulbs in Series Introductory Physics Homework 2