electricity

Discovering the phenomenon of hysteresis in a light bulb

Bulb1The project combined electricity with thermodynamics. An ordinary tungsten bulb was driven at various frequencies and amplitudes, and the resulting non-ohmic and nonlinear behavior was studied and corroborated with simulations in MATLAB, while changing filament geometries and types of incandescent bulbs.

By Azeem Iqbal | Research Stories
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A dipole oscillating in the earth’s magnetic field

Magn_oscillatorThe group determined the earth’s Magnetic field B using a pair of magnets that oscillate about a vertically suspended wire. Magnets when suspended in space respond to the influence of the Earth’s magnetic field. Hence their oscillations are an accurate representation of the value of B. The experiment was performed using different wires and threads. The magnetic moment was determined from the space-dependent magnetic field variation and finally this was used to estimate B.

 

By Azeem Iqbal | Physics Studio
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Candle in the Wind

An electric field can breakdown the insulation properties of air. This creates a mass of oppositely charged ions and electrons that can be pulled towards opposite directions inside the electric field. In this demonstration, we use the plume of a candle flame as the course of plasma. This is a rich structure and would bifurcate into two streams of ions – ionic winds! – moving in opposite directions. The winds can be strong enough to extinguish the flame.

Here is a video demonstration of this effect followed by some photographs of the setup.

Candle in the wind: electric fields can produce ionic winds from Sabieh Anwar on Vimeo.

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Thermal and Electric Properties of a Light Bulb

Bulb2

The aim of the investigation was to probe the electrical and thermal properties of a commercial incandescent light bulb and quantify its temperature using its resistance. The light bulb was also assessed if it behaves like a blackbody and thus follows the Stefan Boltzmann law, for its radiant power and temperature. A thermopile was used to measure the thermal energy emitted by the bulb’s surface, and this in turn was used to compare the transferred thermal power with the temperature of the filament and the bulb’s surface. The results showed that although the filament temperature and surface power do not correlate positively, comparison between surface power and temperature yields a relationship more consistent with Stefan-Boltzmann relationship.

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