The spring constant apparatus is used to verify Hooke’s law and determine the spring constant (k):

It consists of a retort stand with a spring clamped at the top.
A hook is attached to the lower end of the spring to hang slotted weights (100 g to 500 g).
As different weights are added, the spring stretches downward.
A vertically placed ruler beside the spring measures the extension accurately.
Using the formula F = k × x, where F is the force (weight) and x is the extension, the spring constant k can be calculated.
This setup helps students understand elasticity and the linear relationship between applied force and extension in springs.