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Announcement

International Conference on Education in Chemistry (ICEC 2014) Dec 12 to 14 2014

Fourth National Workshop in Hindi (November 14-16, 2014, Allahabad)

# Experimental Development

• Large Amplitude Pendulum

A pendulum may swing at amplitudes greater than 90 degrees if the bob is suspended on a solid rod instead of a string. In this way the increase in the period T with amplitude a can be made much more obvious. This experiment uses angles up to 165 degrees and allows to determine several terms in the Taylor series for T(a). The emphasis is placed on the graphical analysis for the determination of parameters rather than merely checking data against known theoretical values.

• Torsion Pendulum

In this experiment we have studied a relatively complex mechanical system
namely, a Torsion Pendulum and investigated its main parameters. When its rotation axis is horizontal, it displays a simple example of bifurcation.

• Acoustics of a open pipe

At plus two level students often perform experiments with closed pipe resonance. This experiment developed will give students a clear idea about the open pipe resonance. The experiment consists an open pipe excited by a speaker and the resonance effect is captured with the help of a small microphone followed by an amplifier. The resonance effect can be very well seen on the CRO. The experiment does not just stop on observing resonance but it also studies the variation of quality factor with the diameter of the pipe.
As explained above, the experiment demonstrates open pipe resonance. But it also demonstrates a closed pipe resonance just by closing one end with the help of a circular disk.

• Rotating Liquid

A very interesting experiment based on the rotation of the liquid inside a cylindrical container placed on a turn table. As the liquid rotates it takes a shape of paraboloid. By treating this surface as a concave mirror, we can study the variation in focal length with respect to the varying angular speed. In this experiment, we can calculate the acceleration due to gravity and also the refractive index of the liquid used. The experiment is challenging in both designing and performing aspects. It was a really skillful job to design a turn table that rotates with the desired angular velocity and without any wobbling effect. The whole arrangement of the experiment tests the experimental skill of the students.

• Thermal Conductivity of Rubber Tubing

The senior secondary level laboratory has not developed any experiment in the area of heat so far. We worked on this experiment to fill this gap.
In this experiment, the thermal conductivity of rubber tubing is determined by passing steam through it. The tube is immersed in the calorimeter filled with water. The change in the temperature of water in calorimeter is noted while the temperature inside the tube being constant at 100 degree centigrade. An important pedagogic aspect of the experiment is the correction for radiation losses which the students are expected to apply.

• Young’s modulus of a metal bar by strong static bending

This was one of the experiments in the experimental component of Indian National Physics Olympiad Examination 2002. Unlike the usual cantilever experiment the students were asked to study the strong bending of a metal bar by attaching different masses at its free end.

• Acoustic Filters

This was one of the experiments in the experimental component of Indian National Physics Olympiad Examination 2003. The experiment involved studying the frequency response of high pass filter and band stop filter assembly by exciting them using a speaker.

• The Physical Pendulum

The experiment was set for the Orientation cum Selection Camp examination of 2005. The experiment is designed to give a clear understanding of various concepts involved in oscillatory motion and their interrelationship. The experiment consists of many parts interlinked with one another. It demands the use of various experimental techniques and skills such as use of graphs and error analysis which form essential parts of experimental physics. Though the experiment is for five hour duration it can be introduced in the curriculum of experimental physics at Higher Secondary level or at Undergraduate level by breaking it into parts.

• Rolling Motion

In this experiment the rolling motion of a dumbbell shaped body on a plane is studied. The plane is formed by two parallel metallic rails. It is designed to illustrate clearly the different roles of static and rolling friction in the rolling motion.

• Bifilar Pendulum

This experiment studies bifilar pendulum in the form of a dumbbell. The experiment was set for Indian Physics Olympiad Examination – 2006; conducted at the Homi Bhabha Centre for Science Education (TIFR), Mumbai. Students are asked to experimentally determine the relationship between different parameters and arrive at the formula. They are also asked to determine the moment of inertia of the dumbbell around the axis given.

• Conductivity Measurement using Hall Effect

We are interested in the measurement of conductivity of liquids using hall effect. The assembly is set up in the laboratory with electromagnet giving a field up to 0.5 T, the arrangement for the liquid flow. The measurements were done using a simple arrangement with a PVC pipe fitted with probes as graphite pencils. We could see that the Hall voltage was developed between the two leads but with some fluctuations. Now we are planning to repeat this using a well fabricated glass tube fitted with lead probes.

• Strip Oscillator (Demonstration)

This demonstration exhibits a special kind of coupled oscillator. Two steel scales are held tight in a specially fabricated rigid support. The coupling between the two oscillators is achieved either using a spring or two magnets. A 100 g weight (on each scale), whose position can be changed, is hung at the end of the oscillator for getting observable/measurable oscillations. The oscillator can exhibit two normal modes of vibration; 1) when both the oscillator are in phase and 2) when both the oscillators are out of phase.

• Magnetic Black Box

The purpose of this experiment is to study a magnetic black box. The black box is an aluminum tube in which magnets along with aluminum spacers are packed. The number and arrangement of magnets can be determined through this experiment. This experiment develops an investigative approach among students. The students are trained to arrive at the solutions by applying scientific and logical methods.

• Faraday's First Electric Motor (Demonstration)

A demonstration of Faraday's first electric motor was developed. A simple arrangement of a niobium magnet erected in mercury and a copper wire and a dc power supply exhibits working of this motor.

• Anderson's Bridge

The value of an unknown resistance is determined by including it in one arm of a Wheatstone bridge which is then balanced by varying the known resistances in the three other arms. In a similar way we can determine the impedance of an inductive coil by including it in one arm of an ac bridge. While working with ac bridges the impedances of all the four arms of the bridge are set approximately to same order. Then the two variables are adjusted in turn to reduce the imbalance till the best possible balance is observed.