1)

Equal charges q each are placed at the vertices of an equilateral triangle of side r. The magnitude  of electric  field intensity at any vertex is 


A) 2q4πϵ0r2

B) q4πϵ0r2

C) 3q4πϵ0r2

D) 2q4πϵ0r2

Answer:

Option C

Explanation:

 Due to charge  at A and B magnitude of intensity of electric field at point C

E1=E2=14πϵ0.qr2

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 Net intensity at point C is

 ER=E21+E22+2E1E2cos600

ER=E21+E22+2E21×12=3E1=3q4πϵ0r2