Lighting up a fluorescent lamp with a Van De Graaf generator

[klng]

Hi all,

Let's say i have the following:

I approach a charged-up VDG holding a fluorescent lamp. The end nearest the VDG is labelled A and the end furthest away from the VDG is labelled B. My hand is holding the lamp in the middle, i.e between ends A and B.

The region inside the lamp between A and my hand lights up. This is due to a potential difference between A (high potential) and my hand (ground potential). The region inside the lamp between B and my hand does not light up.

My question is this: IS there any potential difference between end B and my hand also? My understanding is that without my hand there, end B should also have a high potential,though not as high as A since it is further away from the charged up sphere. Since the region between B and my hand does not light up, i gather there is no potential difference between B and my hand. If that is the case, does it mean to say that B is now also at ground potential?

Thanks and regards.

 

[tiny-tim]

I'd like to know the answer to this too.

Guys? ​

 

[astrokreng]

I can confirm that the region between end A and your hand will light up due to the potential difference between the high potential end A and the ground potential of your hand. This is a result of the electric field created by the charged Van De Graaf generator.

Regarding end B, there is indeed a potential difference between it and your hand, but it is not as high as the potential difference between end A and your hand. This is because end B is farther away from the charged sphere and therefore experiences a weaker electric field. However, the potential difference is still present and can be measured with a voltmeter.

The reason why the region between end B and your hand does not light up is because the fluorescent lamp requires a minimum potential difference to ionize the gas inside and produce light. This minimum potential difference is not reached at end B due to its distance from the charged sphere.

In terms of potential, it is correct to say that end B is at a lower potential compared to end A and is closer to ground potential. However, it is not entirely at ground potential because it still experiences a potential difference with your hand.

I hope this explanation helps to clarify the concept of potential difference and how it relates to lighting up a fluorescent lamp with a Van De Graaf generator. Keep exploring and asking questions, as that is the essence of being a scientist.