If r is radius of the conductor and R is radius of the sheath

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If r is radius of the conductor and R is radius of the sheath of strength, then

1. r /R > 1·0
2. r /R > 1·0
3. r/R < 0·632
4. r/R < 0·368

Correct Option: D

Gradient at a distance x,

g =	V
	xIn(R/r)

∴ g_min =	V						, and
	RIn		R

			r

g_max =	V
	rIn		R

			r

and plot of the gradient at the surface of the conductor and the ratio (r/R) is shown in the figure and it can be seen that

r	<	1	< 0.368
R		e