# In a Van De Graaff Type Generator a Spherical Metal Shell is to Be a 15 × 106 V Electrode. the Dielectric Strength of the Gas Surrounding the Electrode is 5 × 10^7 Vm^−1. - Physics

In a Van de Graaff type generator a spherical metal shell is to be a 15 × 106 V electrode. The dielectric strength of the gas surrounding the electrode is 5 × 107 Vm−1. What is the minimum radius of the spherical shell required? (You will learn from this exercise why one cannot build an electrostatic generator using a very small shell which requires a small charge to acquire a high potential.)

#### Solution

Potential difference, V = 15 × 106 V

Dielectric strength of the surrounding gas = 5 × 107 V/m

Electric field intensity, E = Dielectric strength = 5 × 107 V/m

Minimum radius of the spherical shell required for the purpose is given by,

r=V/E

=(15xx10^6)/(5xx10^7)=0.3m=30cm

Hence, the minimum radius of the spherical shell required is 30 cm.

Concept: Van De Graaff Generator
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#### APPEARS IN

NCERT Class 12 Physics Textbook
Chapter 2 Electrostatic Potential and Capacitance
Exercise | Q 35 | Page 92
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