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The vertical deflecting plates of a typical classroom oscilloscope are a pair of

ID: 1430897 • Letter: T

Question

The vertical deflecting plates of a typical classroom oscilloscope are a pair of parallel square metal plates carrying equal but opposite charges. The potential difference between the plates is 25.0 V Typical dimensions are about 3.4 cm on a side, with a separation of about 5.0 mm . The plates are close enough that we can ignore fringing at the ends.

a)Under these conditions. how much charge is on each plate?

Express your answer using two significant figures. Q= ____________ C

b) How strong is the electric field between the plates?

Express your answer using two significant figures.E=___________________V/m

Explanation / Answer

a)

A = 3.4*3.4
= 11.56 cm^2
= 1.156*10^-3 m^2

d = 5 mm
= 5*10^-3 m

C = ebsoleneo*A/d
= (8.854*10^-12)*(1.156*10^-3) / (5*10^-3)
= 2.05*10^-12 F
Q = C*V
= (2.05*10^-12)*25
=5.1*10^-11 C
Answer: 5.1*10^-11 C

b)
E = V/d
= 25 / (5*10^-3)
=5000
V/m

Answer: 5000 V/m