(2005?Hangzhou one model) As shown in the figure, the mechanical capacitance of the disk is connected to a small piece of metal under each key, and the metal plate separated from the air gap of a cert

(2005?Hangzhou one model) As shown in the figure, the mechanical capacitance of the disk is connected to a small piece of metal under each key, and the metal plate separated from the air gap of a certain By C=?0< td>d

s
	s

can be obtained:

C=

9×10?12×50×10?6

0.6×10?3

0.6×10?3

=0.75×10-12F=0.75pF;

The capacitor becomes 0.75+0.25=1×10-12F;

The capacitance of the capacitor is changed from C=?0

s

d

can be obtained:

d′=

9×10?12×50×10 ?6

0.50×10?12

=0.45mm;

So, it should be pressed down to 0.60-0.45=0.15mm;

Thus The answer is: 1; 0.15.