Varying the voltage of a light bulb

AI Thread Summary
The brightness of a light bulb is determined by the power it receives, which is calculated using the formula P = VI, where P is power, V is voltage, and I is current. In a parallel circuit, removing one bulb does not affect the brightness of the remaining bulbs because the total power supplied remains constant, and the voltage across each bulb stays the same. The removed bulb does not contribute to the overall power, resulting in no change in brightness for the others. This principle highlights that in parallel circuits, individual components operate independently regarding brightness. Thus, the brightness remains unchanged when one part of the circuit is removed.
sanado
Messages
55
Reaction score
0
Hey guys, was wondering if you could help me with this question:

What determines the brightness of a lightbulb?

I think it would be power (and therefor voltage and current since P = VI) as power is used in the measurement of energy delivered. Why is it the case then that, from the questions i am doing, it states that if you have a simple circuit such as the one shown in the following link (page 11, question 5), why doesn't the brightness vary when one part of the parrallel circuit is removed?

http://www.vcaa.vic.edu.au/vce/studies/physics/pastexams/physics12004.pdf

Question 5, page 11

Thanks
 
Physics news on Phys.org
I don't see the contradiction. There's no power associated with the removed bulb, so it's dark. The power is unchanged for the others*, so their brightness is unchanged.

*P = VI = V2/R, and voltage and resistance are constant.
 

Thread 'Errors and significant figures'

I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
View full post »
Thread 'A cylinder connected to a hanging mass'

Thread 'A cylinder connected to a hanging mass'

Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
View full post »

Similar threads

Current, voltage : brightness of bulb in parallel or series
Replies
2
Views
4K
Differences in the Brightness of bulbs for 2 separate circuits
Replies
1
Views
2K
How to find the power consumed by the light bulb
Replies
19
Views
3K
Voltage & Current & Push & Force & Potential
Replies
5
Views
2K
Light bulb & Diode: linear or non-linear elements.
Replies
12
Views
9K
How Much Power Does a Light Bulb Use in a Series Circuit?
Replies
17
Views
2K
Detecting Phase sequence with light bulbs/ Short circuit voltage
Replies
1
Views
2K
Power Source at 6.0V: Analyzing Current, Voltage, & Resistance
Replies
3
Views
2K
I Does Ohm's Law work for Light Bulbs?
2
Replies
57
Views
11K
Kirchoff's Law - Wire in parallel with light bulb
Replies
4
Views
2K

Hot Threads

Recent Insights

Back
Top