Charged rod in your hand stays charged

[reset_7]

Homework Statement

When you rub a rubber rod with fur it becomes negatively charged. How does it keep it's charge if it's in your hand?

Homework Equations

The Attempt at a Solution

We did this in the lab and it definitely stays charged (at least long enough to observe some other reactions to it). I don't know why it doesn't lose it's charge into me since I'm holding it

 

[rl.bhat]

When you rub a rubber rod with fur it becomes negatively charged. How does it keep it's charge if it's in your hand?

hi rest_7, welcome to PF.
Unlike the metal rod, rubber is an insulator, in which charges are localized. They won't conduct through it to your hand to conduct to the ground. Due to this same reason you cannot charge the metal rod by holding it in your hand.

 

[reset_7]

hi rest_7, welcome to PF.
Unlike the metal rod, rubber is an insulator, in which charges are localized. They won't conduct through it to your hand to conduct to the ground. Due to this same reason you cannot charge the metal rod by holding it in your hand.

Thanks very much for the reply! That makes sense :-) But if it is not a conductor, how come when we brought that charged rubber rod to the pith ball it transferred it's charge to it?

Thanks again!

 

[rl.bhat]

When you bring a negatively charged rubber rod near an uncharged pith ball, electrons on the pith ball are repelled back due to the repulsive force leaving the surface near the rod positively charged. When you touch the pith ball with the rod, electrons are transferred from the rod to the pith ball.

 

[reset_7]

When you bring a negatively charged rubber rod near an uncharged pith ball, electrons on the pith ball are repelled back due to the repulsive force leaving the surface near the rod positively charged. When you touch the pith ball with the rod, electrons are transferred from the rod to the pith ball.

Thanks for your time in helping me out. I guess that's what is confusing me. That the rod cannot transfer the electrons to me (because it's an insulator) but it can transfer those electrons to the pitch balls. Am I missing something?

 

[willem2]

The charges can only go from the surface of the rod, directly to anonther object that's touching the surface. If you swiped the entire surface of the rod with your hands, you could discharge it as well.

 

[reset_7]

The charges can only go from the surface of the rod, directly to anonther object that's touching the surface. If you swiped the entire surface of the rod with your hands, you could discharge it as well.

Fantastic, thanks for all your help!