Project Title Modeling the collisions of electrons with Hg vapors
Students Muhammad Sheroz Malik
Session Summer 2015

A bi-directional current source is needed so as to exploit the Peltier device’s heating and cooling phenomenon: one face of the device heats up when current flows in one direction and the same face cools down if the current through it flows in the opposite direction.

The idea is to use transistors as a voltage to current amplifiers. The op-amp is used to complement the same purpose: it provides the initial voltage signal at the base of the transistor so that the transistor may operate at such ADC-biased base voltage configuration where current to voltage amplification takes place. Another consideration is the fact that the DAQ (we use DAQ as out input voltage source) only provides a certain amount of output voltage. Keeping this practical constraint view, the op-amp or any voltage to voltage amplification device becomes a necessary part of the circuit.

Mainly, following components have been used:

  • Dual polarity power supply
  • 741 Op-amp
  • Resistors of various values as indicated in the diagram above
  • BJT BD 243C (NPN transistor)
  • BJT BD 244C (PNP transistor)
  • Betatherm NTC thermistor 2.2k3A359I
  • NI-USB 6001
  • Peltier device labelled as LOAD in the above diagram

Project Title Coincidence detection circuits for photon correlations
Students Muhammad Ramish Ashraf
Session Spring 2017

Coincidence detection is the simultaneous detection of two or more photons in different detectors. The electronics associated with coincidence-counting tend to be very costly. The aim of this project was to build a small and an affordable circuit based on fast logical AND Gates. The circuit includes a pulse compressor which, depending upon the setting of the multiplexer, can either shorten the input pulse width or let it pass through unchanged. The different available widths that can be obtained are as following:

  • 10 ± 0.2ns
  • 12.8 ± 0.2ns
  • 14.4 ± 0.2ns
  • Original Width  

After the desirable pulse width has been achieved, the output of the pulse compressor is input into a fast (SN74F08) AND gate from which twofold and threefold instances are measured. The circuit comprises of 4 such channels (A, B, C, D) and their complements. The coincidences available are as follows: AB, BC, AC, CD, BD, ABC, ABC.

The project, which was part of Ramish’s independent study was supervised by Dr. Sabieh Anwar and the circuit was built by Mr. Shafique, R.A. spin physics group.

 


Project Title Hot Water Fountain
Students Aliza Shahid
Session IYPT 2016

Aliza also worked on “Hot Water Fountain” problem. It involved creating a hot water fountain using a partially filled Mohr pipette. The hot water raised the temperature of the air column inside the pipette resulting in an increased pressure. As the pipette was turned with its tip upwards, a stream of hot water fountain was observed exiting the tip. Through this performance parameters such as describing the height of the fountain and its dependence on the temperature of water and the volume of air column and optimization to get the maximum height was performed.

 


Project Title Mechanical Random Number Generator
Students Shaheer Akhtar
Session IYPT 2016

Shaheer worked on making a mechanical random number generator. An electromagnet drops a ball onto a rod that is exactly beneath it, and the ball will fall onto either the right or the left side of this rod. If the balls falls onto the left side, a reading of ‘1’ is taken. And if it falls onto the right side, a reading of ‘0’ is taken. After dropping the ball like this many times, a stream of ‘randomnumbers is obtained.

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Project Title Acoustic Lens
Students Aliza Shahid
Session IYPT 2016

Aliza Shahid worked on acoustic amplification using a “Fresnel lens”. These are primarily used in optical applications but the IYPT student was asked to investigate its application to focus acoustic waves. The Fresnel lens was manufactured using the 3D printing facilty at Physlab. The design consisted of a flat lens composed of perforated air channels in the form of concentric rings. The sound waves diffract through these channels and undergo constructive interference creating a focal point where an amplified sound can be detected.


Project Title Magnetic Train
Students Muhammad Ahad Butt
Session IYPT 2016

11939696_919092211495509_2028985967_nMuhammad Ahad Butt was asked to attach button magnets to both ends of a cylindrical battery. When placed in a copper coil such that the magnets contact the coil, the “train” starts to move. Ahad used a ‘Push and Pull’ phenomena of forces to describe this movement. He further investigated the different parameters that affect the Magnetic Train such as Eddy Currents and Friction.These parameters were altered and the results were used to for graphical analysis. A mathematical model of the train was developed. In addition computer simulation software were used to produce optimal Models of the Train that maximized acceleration, speed and efficiency.

 


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