# To find minimum distance
# Modern Electronic Instrumentation And Measurement Techniques
# By Albert D. Helfrick, William D. Cooper
# First Edition Second Impression, 2009
# Dorling Kindersly Pvt. Ltd. India
# Example 7-1 in Page 184
# Given data
D = 4*10**-2 #Deflection on the screen in m
G = 100*100 # Deflection factor in V/m
E_a = 2000 #Accelarating potential in V
#Calculations
# wkt. L = 2*d*E_a/(G*I_d)
#Also L/D = I_d / d
#Therefore
L = math.sqrt(2*D*E_a/G)
print "The distance from the deflection plates to the oscilloscope tube screen = ",round(L,3),"m"
#Result
# The distance from the deflection plates to the oscilloscope tube screen = 0.126 m