arXiv subjects

Raju Baddi

Publications and source records attributed to Raju Baddi.

11 recordsLinked to original sources

arXiv2013

How to Demonstrate the Voltage on a charged object in Physics Laboratory

Common Objects like a comb or a pen get charged when rubbed against something like human hair or garment clothing. Charged objects exhibit noticeable attractive or repulsive force lifting small pieces of paper or pushing/pulling a suspended light object charged with the same/opposite(uncharged) polarity respectively. This indicates the strong electrical nature of charged objects. Flashes due to spark between oppositely charged objects can be seen in total darkness. Implying a large potential difference between these charged objects which is not possible at lower voltages. This article describes a method to measure the voltage on commonly charged objects with respect to earth using simple instrumentation based on capacitors and CMOS voltmeter. Once the potential difference is known the average charge on the object can be calculated as well. The article also suggests a simple femto-farad capacitance meter for electrostatics work.

physics.ed-ph↗

arXiv2013

Transistor as a Rectifier

Transistor is a three terminal semiconductor device normally used as an amplifier or as a switch. Here the alternating current (a.c) rectifying property of the transistor is considered. The ordinary silicon diode exhibits a voltage drop of ~0.6V across its terminals. In this article it is shown that the transistor can be used to build a diode or rectify low current a.c (~mA) with a voltage drop of ~0.03V. This voltage is ~20 times smaller than the silicon diode. This article gives the half-wave and full-wave transistor rectifier configurations along with some applications to justify their usefulness.

physics.gen-ph↗

arXiv2012

Bipolar Transistor Tester / Digital IC Tester for Physics Lab

A very simple low cost bipolar transistor tester for physics lab is given. The proposed circuit not only indicates the type of transistor(NPN/PNP) but also indicates the terminals(emitter, base and collector) using simple dual color (red/green) LEDs. Color diagrams of testing procedure have been given for easy following. This article describes the construction of this apparatus in all detail with schematic circuit diagram, circuit layout and constructional illustration. The second part describes a simple circuit to test digital ICs in a physics lab. Small scale integration digital ICs like logic gates, flip-flops, registers, counters, decoders, multiplexers etc are used in physics lab for various purposes either in a commercially obtained equipment or lab made circuits. The non-functionality of a circuit may call for a test of the digital chip. Commercially available test equipment is expensive, bulky and some times useless with regard to the concerned test. This article describes an inexpensive, portable and useful digital IC test circuit that could be helpful in detecting the actual fault with the chip provided the data sheet for the chip is available. In a very convenient and easy way. The article contains neat diagrams and illustrations to help the reader build a proper functional digital IC tester.

physics.pop-ph↗

arXiv2012

A survey of Radio Recombination Lines using Ooty Radio Telescope at 328 MHz in the Inner Galaxy

A survey of radio recombination lines in the Galactic plane with longitude $-32^o < l < +80^o$ and latitude $b<\pm3^o$ using Ooty Radio Telescope(ORT) at 328 MHz has been reported. ORT observations were made using a New Digital Backend(NDB) augmented to it recently. With NDB ORT had a beam of $2^o.3 \times 2^o.2 sec(δ)$ and a passband of $\sim$1 MHz in the spectral line mode. The above mentioned Galactic region was divided into $\sim 2^o \times 2^o$ patches with the ORT beam pointed to the center. The ORT observations form a study of distribution of extended low-density warm-ionized medium(ELDWIM) in the inner Galaxy using H271$α$ RL. By obtaining kinematical distances using $V_{LSR}$ of the H271$α$ RLs the distribution of ELDWIM clouds within the inner Galaxy has been deduced for the region given above.

astro-ph.GA↗

arXiv2012

Helium line detections from ELDWIM at 1.4 GHz

Helium line observations towards 11 Galactic positions using Westerbork Synthesis Radio Telescope(WSRT) have been reported. These observations were made towards nearby positions where already hydrogen lines were detected at sufficiently high intensity($\geq$50mK) at 1.4 GHz. This approach gave a fair chance for the detection of helium line as well, keeping in mind the relative abundance(10%) of helium with respect to hydrogen. Care was also taken to avoid the presence of HII regions along the line of sight so that the line emission originates from the extended diffuse low density ionized component, ELDWIM of the Galaxy. The observations have resulted in the detection of helium line towards 5 positions out of 11 with signal to noise ratio(snr) $>$ 4$σ$. An attempt has been made to associate detection/non-detection of helium line to the presence of surrounding HII regions. A weighting scheme that accounts for nearby($<$ 500pc) HII regions, their distances and other factors produces favourable results. It is seen from this weighting scheme that a higher weight favours the detection of helium line while lower weight is associated with non-detection. The idea is to correlate ionization of ELDWIM with the surrounding HII regions.

astro-ph.GA↗

arXiv2012

Differential Stroboscope for Physics Lab

A conventional stroboscope uses flashes of light to make a rapidly moving object visible. This is achieved by throwing repetitive pulses of white light on the object of specific frequency. Here an alternative approach is given in which two different colors of light(red/green) are used to make a rapidly moving object visible. As such this method has two light pulses of different colors within a single strobe period. Such a stroboscope has its own advantages in experiments over the conventional one. This article describes the construction of this stroboscope in all detail. Various aspects of its performance are discussed pictorially with reference to a simple rotating disc. This stroboscope can be used in the study/quantitative-assessment of rapidly moving objects which by default are taken to be cyclic in nature.

physics.gen-ph↗

arXiv2012

High Voltage Generation for Physics Lab

A power efficient way to generate low power high voltage is given. The article describes various aspects of functioning and derives quantitative relations between different parameters and high voltage generated. Use of voltage multiplier (Cockcroft-Walton multiplier) network can provide further boost in the high voltage(~1000V).

physics.pop-ph↗

arXiv2012

Free Fall Frame to Demonstrate Weightlessness

A simple apparatus to demonstrate free fall weightlessness is given. This can be easily constructed from readily available materials and can be used for the demonstration purpose to an audidence with all the details of the apparatus visible.

physics.ed-ph↗

arXiv2012

Bi Event Timer for Physics Lab

Ubiquitously during experiments one encounters a situation where time lapse between two events has to measured. For example during the oscillations of a pendulum or a vibrating reed, the powering of a lamp and achieving of its full intensity. The powering of a relay and the closure of its contacts etc. Situations like these call for a time measuring device between two events. Hence this article describes a general Bi-Event timer that can be used in a physics lab for ubiquitous time lapse measurements during experiments. These measurements in turn can be used to interpret other parameters like velocity, acceleration etc. The timer described here is simple to build and accurate in performance. The Bi-event occurence can be applied as a signal to the inputs of the timer either on separate lines or along a single path in series as voltage pulses.

physics.ed-ph↗

arXiv2012

High Voltage Electrostatic Pendulum

A pendulum powered by high voltage electricity is described. The pendulum consists of two conducting plates(thin foil) separated by copper rods and are insulated from each other. High voltage is applied to these plates through the connecting copper rods. Another stationary aluminum plate(thin foil) is placed in front of the pendulum such that it serves to attract the pendulum plates and makes electrical contact with them enabling charge transfer between the stationary plate and the pendulum plates. The pendulum is powered by the energy stored in the capacitance between the stationary aluminum plate and the pendulum plate. Attempt has been made to obtain the time period of oscillations as a function of applied voltage and other parameters. The derived formula for the time period has been verified experimentally. This apparatus can be used to demonstrate electrical phenomena in general and in particular electrical energy stored in conductors of small dimensions.

physics.pop-ph↗

arXiv2011

Improved Astable Multivibrator

The conventional two transistor astable multivibrator has been modified to produce better waveform which are more steeply rising and falling than those from the conventional astable. The improvement in the waveform is achieved by using a diode pair in each collector branch of the transistors. This restricts the direction of current flow for the charging and discharging of the timing capacitors. This article also derives the time period of oscillations for the modified circuit and discusses the limits on source and sink currents at the transistor collectors.

physics.pop-ph↗