A closely coiled helical spring of radius R, contains n turns and is subjected to an axial load W. If the radius of the coil wire is r and modulus of rigidity of the coil material is C, the deflection of the coil is

A closely coiled helical spring of radius R, contains n turns and is s

1.	A closely coiled helical spring of radius R, contains n turns and is subjected to an axial load W. If the radius of the coil wire is r and modulus of rigidity of the coil material is C, the deflection of the coil is
A.	<img src="/_files/images/civil-engineering/strength-of-materials/140-6.211-1.png">
B.	<img src="/_files/images/civil-engineering/strength-of-materials/140-6.211-2.png">
C.	<img src="/_files/images/civil-engineering/strength-of-materials/140-6.211-3.png">
D.	<img src="/_files/images/civil-engineering/strength-of-materials/140-6.211-4.png">
Answer» E.