Physics and Math Content Review Section 4 Content Review Problem Question 71

whitebrush
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Physics and Math Content Review Section 4 Content Review Problem Question 71

Postby whitebrush » Fri Nov 03, 2017 1:16 am

Physics and Math Content Review Section 4 Content Review Problem Question 71

First, I feel confuse about the second paragraph: "When lightning strikes, some of the negative charge of the cloud neutralizes the positive charge of the Earth". This demonstrates that more positive charges on the Earth surface, and more negative charges on the cloud. But after that, it said "4C of negative charge pass from ground to the cloud", here, I thought it should be positive changes move to cloud, because it needs to neutralize the charge imbalance, and more positive changes on the Earth surface.

Second, because of confusion about which (ground or cloud) has more positive change, I am not certain which type of charges that the lightning rod will bring, and so choose A, but it said that B is the correct answer. Could you confirm this?
NS_Tutor_Andrew
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Re: Physics and Math Content Review Section 4 Content Review Problem Question 71

Postby NS_Tutor_Andrew » Fri Nov 03, 2017 10:15 pm

Hi whitefish,

Thanks for the excellent question. It looks like this must have been a typo -- the only way for this to make sense is if the 4 coulombs of negative charge pass from the cloud to the earth. The passage is quite clear about the earth having a positive charge induced by the cloud. Therefore, lightning rods will be especially positively charged in order to 'attract' the lightning, making B correct. Hope this helps!
Andrew D.
Content Manager, Next Step Test Prep.

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