ABHINAV 4th week (Aug 23th to 26th, 2011)

                                                        Resistor

The resistor are used to control the amount of current and voltage flowing through the circuit.
Resistor can be identified by a code using the colour and position of the bands.

• Here the first two or three bands are numbers to write down.
• Next band is the multiplier (numb of zero added to a number)
• gold multiplier makes one decimal place smaller and silver makes two decimal places smaller.
• last band to right may be the tolerence values.

example: green,blue,red,gold
= 5(green)6(blue) x 2(that is 100 ohms) +- 5%
=56x100ohms+-5%
=5600ohms+-5%
low tolerance= 5600ohms -5%
high tolerance=5600ohms+5%
we took 6 resistors to practice, determine there value with like above example  and also measured the values through multimeter and , measured the low and high tolerance.

Then choose the 2 resistors  and recorded their individual ohm resistance value , measured it through the multimeter.
R1=5.520
R2=315.0
Then measured the value by connecting both the resistor in series and in parallel.
R1 + R2 in series=320.52

R1 + R2 in parallel=5.420

Here we demonstrated with this,that as in series the resistance add up and in parallel the resistance divides by two parallel and total resistance is lower then lowest branch of resistor.


                            


*                             Testing diodes  


Diodes- diodes alow electricity or current to flow in one direction and stop current flow in other direction.The arrow points in the diode indicates the direction of flow for conventional flow of electricity from positive to negative. 


We were asked to measure diode with the"diode test"
 Here we were asked to  identify the direction of flow of diode  by making a suitable diagram,

  
Then measured the resistance of diode in both direction by using multimeter at 2KOhms

the result measured was: 

• anode to cathode- infinity ohms
• cathode to anode- 0
  

After this we check the voltage supplied with the help of 2meters, where 1meters was set in ohms positions and another meter on DC volts with the 2K ohms position(need to touch positive with positive and negative with negative props)

recorded value = 0.6V, it wasn't enough voltage for theoretically push through the bindery layer of the diode.

After this the ohm measurement was done ,which was not effective because the meter did not put its enough power to push through the diode bindery layer.then use diode test position to measure the diode in both direction with the value from anode to cathode was 0.7V,here the voltage is able to pass from anode to cathode and from anode to cathode it was 0 as it is blocked in direction, so this indicate the diode is in good condition.

Then we builded a circuit with a diode and resistor with one K ohm resistor and used 12V supply, measure the voltage drop accross R & D, which was 13.15V And 0.83V.then measure the amp flow through the diode was 0.02A, measure the available voltage at battery(supply Vs)= 13.98V and added the voltage drop accross R & D, vdr + vdd = 13.15+0.83= 13.98V

Applying the rule of electricity, these reading demonstates that as it is series circuit and voltage is being supplied to the two consumers inthe circuit . so the resistor and doide are restricting and consuming the voltage all over.

Then change the restance by replacing the resistor with the higher value resistor size 4.8K ohms ,voltage drop accross R 13.20V, voltage drop across D.79V and amp flow through D 0.011A, Here while using higher value restor changes the voltage drop at R & D but there is still little amp flow through the diode because the diode will always have some resistance.

And in last tested Led with the meter on diode test position and anode to cathode = 1.750V And C to A = 0V. On comparing voltage drop of normal diode and LED we knew that LED consume more voltage as needs more volts to glow now and then builded a same circuit with the addition of LED, Here the voltage in LED is higher because there is high resistance, but there is low resistance in diode


  *                                                     CAPACITOR


The capacitor stores electric charge, consist of two metal plates very close together seperated by insulator .when connected to battery or power source electron flows in the negative plate and charge up the capacitor.
Types of capacitor

• Non-electrolytic capacitor
• variable capacitor
• Electrolytic capacitor
• Tantalum capacitor

Identification of capacitor : it is neccesory to identify the capacitor size, if the farad size is not printed on the capacitor we should find EIA

Then took 4 different capacitor of different capacitance 10,1,100and 300uF. , calculated the charge of capacitor using formula R x C x 5= T . then evaluated the charge time on the given tick table, where the capacitance for 10,1and 100 were ticked as No and 300 F was ticked yes as it can be charged in the calculated time 

After that calculated resistor size and build a capacitor charging circuit.

Components needed in circuit:

• 1   resistor
• 1  Capacitor
• 1  bridging wire 
• 1  voltage (battery or power supply)

Then we started performing on it, did a visual check on circuit and started monitoring capacitor charge time verse voltage, we remove the bridge wire ans started recording the voltage after every ten seonds for 220 seconds or 3.7 minutes and after having all the readings plotted the capacitor charge up time on the graph.

According to the graph, the capacitor voltage was low when we started the test. Bit as time goes on, as we noted for every 10 sec the capacitor slowly starts building up voltage and stores it.the voltage increase as the time increases,so that indicates its charging.As it act to the it starts slowing down.When capacitor connects to the bulb the load starts discharging. It is using a voltage that is stored.