p19_011.pdf

10 − 6 / C ◦ ,

according to Table 19–2). The range of values for the diameters can be found by setting ∆ T equal to

the temperature range. Thus ∆ D =(3 . 2

10 − 6 / C ◦ )(200 in . )(60 C ◦ )=3 . 84

10 − 2 in. Since 1 in . =

2 . 50 cm = 2 . 50

10 4 µ m, this is 960 µ m.

11. When the temperature changes from T to T +∆ T the diameter of the mirror changes from D to D +∆ D ,

where ∆ D = αD ∆ T .Here α is the coecient of linear expansion for Pyrex glass (3 . 2