Capillary rise

Surface tension of a liquid can be determined by this method. Capillary tube which is cleaned by ultrasonic rays is mounted vertically through a hole in a cork fitted to a stand. The capillary tube should be uniform throughout its length. Liquid whose surface tension is to be measured is taken in a beaker. The lower end of the tube is kept immersed in thios liquid. The a vertical pointer is passed through the cork. The beaker now raised so that the liquid wets the inside of the tube. The pointer is now adjusted so that its tip just touches the liquid surface in the beaker.

Static torsion

Here we determine the rigidity modulus of the material of the given rod using Searle’s static torsion apparatus. This apparatus consists of a stout metal frame with a cylindrical rod arranged horizontally, the end of which is firmly fixed to a frame. The other end is tightly held by a chuck at the edge of a smooth pulley. One end of the tape is fixed on the rim point with winding over pulley through the groove. A weight hanger is designed at the free end of the tape. Twist produced on the rod is measured using a scale and telescope arrangement.

Compound pendulum

This device is used to determine the acceleration due to gravity at a place. It consists of a uniform rectangular bar, some one meter long, with some equidistant holes drilled on it. It is suspended by a parallel knife edge passing through any of these holes. A vertical pointer is arranged in front of the pendulum to mark its exact equilibrium position. The pendulum is then made to oscillate. The oscillations should be of small amplitudes in a perfectly vertical plane. From the time for some limited number of oscillations, we can determine the acceleration due to gravity at one location.

Screw gauge

This device is used to determine the diameter of a piece of wire. It consists of a U-shaped frame. This frame is attached to a hollow cylinder. A scale graduated in millimeters is marked on the cylinder along its length. This is called pitch scale. A screw is working through the hollow cylinder. The tip of the screw is plane. The other end of the screw is attached to a fine sleeve with a beveled edge. This is called head scale. The pitch of the screw is the distance moved by the tip of the screw for one complete rotation of the screw head.

Vernier calipers

This device is used to measure length of some blocks. It consists of a metallic scale with a jaw fixed at right angles to it at one end. Another jaw which is movable carrying a vernier scale slides over the metallic scale. One precaution is that the inner surfaces of the jaws are plane. When both the jaws are presses together, the zero of the vernier should coincide with the zero of the main scale. If it is not coinciding, zero error exists. Then we have to incorporate zero correction term. The least count of the vernier is the smallest length that can be measured accurately with it.