Class 12 Physics, CBSE and UP Board, Electrostatic Potential and Capacitance, Additional Exercise,Chapter-2 Exercise 2.24, NCERT Solutions for Class 12 Physics
What is the area of the plates of a 2 F parallel plate capacitor, given that the separation between the plates is 0.5 cm? [You will realise from your answer why ordinary capacitors are in the range of μF or less. However, electrolytic capacitors do have a much larger capacitance (0.1 F) because of very minute separation between the conductors.]
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Capacitance of a parallel capacitor, V = 2 F
Distance between the two plates, d = 0.5 cm = 0.5 x 10-2 m
Capacitance of a parallel plate capacitor is given by the relation,
C= ε0A/d
A =Cd/ε0
Where,
ε0 = Permittivity of free space
Therefore A= 2x 0.5 x 10⁻²)/(8.85 x 10⁻¹²)
Therefore, A = 1130 km²
Hence, the area of the plates is too large.
To avoid this situation, the capacitance is taken in the range of μF.