The force required to stretch a spring varies with the distance as shown in the figure . If the experiment is performed with the above spring of half the length, the line OA will

Spring constant,  k=Fx= slope of F-x graph. k∝1l                        (∵x≃0)Length is reduced to half. Therefore, k will become two times. Slope will increase. Hence, the line OA will shifttowards F-axis.