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Part of Made in India,Design Innovation
Workshop,2015
A Fresh New Experience in Project-‐Making & Learning!
Do you know that a capacitor is so ubiquitous that it is rare that an electrical or electronic product does not include at least one for some purpose? Besides being used as an energy storage device, it is used in filter circuits, tuning circuits (for radio, TV, transmiMers etc.) and also as shock absorbers in voltage stabilizers. You can learn about the funcRoning of a capacitor and how the voltage across it changes when it gets charged.
This project is divided into two phases. In the first phase, a resistor, a capacitor and an LED are connected in series on the breadboard. The mulRmeter probes are connected to the capacitor for a constant voltage measurement across its terminals, before supply is given to the circuit. Immediately aTer the supply is given, the LED starts
to glow with maximum intensity and the meter shows an instantaneous voltage reading of 0 V. The meter will show a conRnuously increasing voltage which becomes steady aTer someRme. The LED slowly fades out.
The iniRal, transient and steady voltages were observed and the same were compared with theoreRcal values of voltages using the Rme constant (t =RC) calculaRons. It was noted that the voltage across the capacitor at any given Rme is equal to the sum of iniRal voltage and 63% of the difference between the baMery voltage and the iniRal voltage on the capacitor. When the voltage-‐Rme graph of a charging capacitor was ploMed, it showed that the voltage in the capacitor increases exponenRally and then becomes constant.
In the second phase, the baMery was removed and the same charged capacitor was connected in parallel to the series combinaRon of another LED and a resistor. It was found that the LED glows for a moment with a maximum voltage across the capacitor. Similarly as above, the voltages on the capacitor in different states were compared with the theoreRcal voltages calculated using the Rme
constant. Note that in this case, the Rme constant is the Rme the capacitor takes to discharge 37% of voltage on its plates. When the voltage-‐Rme graph of the discharging capacitor was ploMed, it showed that the capacitor loses its voltage exponenRally and the voltage becomes constant aTer some Rme.
Have a look at what we provide in our Project Kit!
CoolJunk is India's fastest growing DIY (do-‐it-‐yourself) kits company focused on project-‐based learning in science, engineering and technology. Having 20,000 users in India, US, Singapore, Middle East and New Zealand, the CoolJunk kits are known for quality, innovaRon and high producRon value. CoolJunk has been featured in naRonal and internaRonal journals including Wallstreet, Yourstory, Hindu Business Line, NextBigWhat and was tagged as the coolest Indian start-‐up in IAN Bootcamp-‐2011.
You may also refer to the video: Charging & Discharging a Capacitor CreaAng spark using a Capacitor
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