Electric Arc
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Discharging 2 uF 100 KV Capacitor with 10M ohm resistor cause a long-time weak arc.This experiment is done in High Voltage Lab. of University of Tehran. eng.ut.ac.ir
Lie Detector
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A lie detector is an instrument uses to detect blood pressure, respiration and pulse. This instrument usually uses as a forensic instrument. It is commonly used in police station for investigation but this simple instrument can be use in your house.
This article tries to give you information to make a simple lie detector. Lie detector is also known as a polygraph. This simple detector can be extremely helpful if you want someone to tell you the truth. This simple instrument may be not as high-tech as the expert use but it could help you. This instrument operates by assessing the resistance of the skin that will down when you lie. Your skin will go down when you lie because lying will make you feel uncomfortable and nervous. This reaction will make your skin go down.
The first thing to do before making the detector is preparing all the details. Here is the list:
1. MISC 1 Case, Wire, Electrodes (you can use electrodes with alligator clip but you can also uses wire or strap like in hospital), the simple one is wires and tape.
2. 4.5V batteries (2)
3. electrolytic Capacitor C1 1uF 16V
4. R3 1 1.5K 1/4 W Resistor
5. Q1 1 2N3565 NPN Transistor
6. Analog meter M1 1 0-1 mA
7. R2 1 5K Pot
8. R1 33K 1/4W Resistor
These components can be easily found in electrical shops. You can read on the components part to make sure that you have bought the right things. Then you can put and attach each component with the wire. Connect the batteries separately using wires. Put the analog meter between the batteries, so there will be battery wires battery using the wires between the batteries you put the R3 and analog meter. Then, the R1 and R2 after the analog meter is put there. Q1 is near the electrodes.
You need to adjust the analog meter to 0. Attach the wire using tape to the back of the subject’s hand. If the analog meter changes from 0 it means that the subject is lying to you.
Joy Physics- exp #19 Electric circuits 1
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A commercial resistor’s resistance is found by reading the color code, then measured directly by a multimeter. Next, the resistor’s maximum safe voltage and current are calculated, and the resistor is connected to a battery with a safe voltage. Next, the voltage across the resistor and the current through the resistor are measured by the multimeter and the resistance is calculated indirectly using Ohm’s law. Finally, all three resistance values are compared.
Load Break Switch
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In power applications, switches perform function to energize or unenergized an electric load. On the high end of the scale are load-break switches and disconnecting switches in power systems at the highest voltages (several hundred thousand volts).
Load-break switches are required to maintain the capability of interrupting the load current. The load break switch in a circuit with several hundred thousand volts, designed to carry a large amount of current without overheating the open position, having enough insulation to isolate the circuit in closed position, and equipped with arc interrupters to interrupt the load current.
Load break switches of air break are of versatile switch gear for transformer control & protection. They can also be used for Motor feeder in conjunction with Vacuum contactors. They are highly useful for Ring feeders for isolation of faulty section either manually or through remote control if fitted with motor operation. Load break switch in conjunction with HRC fuse can tackle high fault current and offer very good protection against dead short circuit capacity up to 40KA.The fault clearance and isolation through this combination will be achieved in a few milli seconds provided a proper selection of LBS and fuse is done. HRC fuses are manufactured with silver strips/silver coated Cu. Strips wires surrounded by granular quartz. When short-circuit occurs the metal element melts and the molten metal melts the surrounding quartz, making the combination an insulating material, called fulgarite. There will be a number of sections in the element which will create similar insulating media in quick succession and thus the arc will be extinguished in a matter of few milliseconds, say 5 to 8 milli-seconds, ie., less than 1/2 a cycle.
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