[Physics] Question about X-rays hitting a gold leaf electroscope

electrostatics

If X-rays are incident on gold leaf electroscope , leaves always collapse whatever be the charge on leaves. Why?

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The X-rays ionise the air around the gold leaf electroscope.
Charges in the air of the opposite sign to that on the electroscope are attracted to the electroscope and discharge it.

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[Physics] Determine Charge With Electroscope

I did a google search and found that: When a glass rod is rubbed with a paper towel, the glass becomes positively charged.

Therefore:

1.)ground the electroscope through touching it with you fingers (removing any excess charge); one can assume it is neutral/has no net charged at this point.

2.) touch one of the charged rods to the electroscope. The leaves should rise with an unknown charge.

3.) Vigorously rub the uncharged glass rod with a paper towel to give it a positive charge.

4.) bring the positively charged rod close to the Electroscope. If the leaves are repulsed, then you know that the glass rod of unknown charge was/is of the same charge, and therefore is positively charged. Opposite charges attract. Therfore if the leaves attract one knows that the glass rod of unknown charge was negatively charged.

5.) [check] repeat steps 1-4 to verify that that last rod is of opposite charge.

[Physics] X-rays through a Gold Leaf Electroscope

X-rays 'knock' one or more electrons from some of the air molecules, so the air is now partly ionised: there are positively charged ions and electrons (which may attach themselves to neutral molecules to make negative ions). The electrons (or negatively charged ions) are attracted to the leaf-and-plate assembly (if this had been positively charged) and surrender their excess electron(s), so gradually discharging the leaf and plate. The positive ions are attracted to the metal parts of the case of the electroscope, for these will have been charged negatively.

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[Physics] Determine Charge With Electroscope

[Physics] X-rays through a Gold Leaf Electroscope

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