How does UV light pass a glass bulb?

[nickek]

Hi!
A classic example in order to demonstrate the Photoelectric Effect, is to charge a metal plate (by electrons) connected to an electroscope and observe how the charge decreases when lightning by UV light. When put a pane of glass in front of the metal plate, we observe that the charge remains constant, i.e the high energy photons from the UV lamp do not pass the glass. But how do the high energy photons pass the lamp bulb, made of glass?

 

[random54]

After some research through internet I found out they use quartz glass instead of normal one so the UV light can pass through it.