The experiment also helped the student to see the voltage drop across the diode was almost the same each time. This lab showed the effects of current and voltage in a parallel circuit. This experiment also showed how the brightness was effected by changing the voltage. Equipment and materials: Millimeter Power Supply Connecting wires A bread board A 330 ohm resistor AY k ohm resistor 2 Red Lead’s Theory: A light-emitting diode (LED), is an electronic light source.
The first LED was built in the 1925 by Oleg Valedictorian Loose, a radio technician who noticed that diodes seed in radio receivers emitted light when current was passed through them. The LED was introduced as a practical electronic component in 1962. All early devices emitted low-intensity red light, but modern Leeds are available across the visible, ultraviolet and infra red wavelengths, with very high brightness. [l] Figure 1. Basics Physics principle of an LED Lead’s are semiconductors. They will only work if placed in the correct direction.
Placing the LED in the improper direction could potentially damage it. The LED could also be damaged if it was not installed with the use of a resistor. They can not be connected directly to a power source. The anode is the positive end and the cathode is the negative end. Leeds are beneficial because they do not require much voltage to be illuminated. The Leeds are great for conservation of energy . When we subtract the LED voltage from the supply voltage it gives you the voltage that must be dropped by the dropping resistor. A decrease in voltage will result in a decrease of the brightness of the bulb .
Figure 2 shows the electrical symbol and the actual shape of an LED. Figure 2. Electrical symbol and the actual shape of an LED Ohms law is used to be able to calculate the current and the resistance across each of the elements in the circuit. To analyze the circuit It must be known that the voltage is the same in a parallel circuit. The current is the same in a series. The current through each branch can be added up in order to determine the current from the source. From Kerchiefs loop law it can be determined that the sum of all of the voltage drops around a closed loop must sum to equal zero.
The objective of this lab was for the student to use their knowledge of items such s Lead’s, series and parallel circuit configurations, Kerchiefs laws, and Ohm’s law in order to properly analyze and solve problems with given circuit.  Light Emitting Diodes, http://en. Wisped. Org/wick/Light-emitting_diode Procedure: First thing we did in the lab was to create the circuit. We created the circuit by using resistors with values of RI = 330 ohms and OR = I k ohms and also by placing the Leeds after the Resistors so there would be no damage done to the Leeds.
This s shown in figure 3. The voltage supply was set at 8 Volts and then we tested the values for voltage and current. To measure voltage the meter has to be in Parallel with the circuit. Current is measured by placing the Millimeter in series with the circuit. In preparation for the experiment we built the circuit (shown below) using Multi. We used simulations to get all the required measurements and used Ohm’s Law (E=I*R) to solve for the rest. In the lab we set up the same circuit by connecting the resistors and the Lead’s in a parallel circuit to the power supply.
Most of the connections were done using the breadboard. We measured current by placing the Millimeter in series with the entire circuit. We set the Millimeter to measure amperes and turned the power on. We continued this using the 8, 6, 4, and 2 volts (adjusted on the power supply) while noting the brightness of the Lead’s and writing down the value given by the Millimeter. We then connected the Millimeter in parallel with each resistor and Lead’s to measure voltage. We set the millimeter to volts then cycled through 8, 6, 4, and 2 volts on the power supply and noted the reading for each connection.
We then used Ohm’s Law to calculate the current through as well as the resistance for each LED. We also lactated the entire current to see if it matched what we measured. Figure 3 Circuit built in the lab Sample Calculations: To calculate the current through each resistor-LED branch, Ohm’s Law (V = IR) was used. In this Lab the equation used was I RI = IVR / R 1 Example: IR = IVR / RI = 5. 8 V / 3300 Q = 0. 0176 A To calculate the total resistance of each LED, Ohm’s Law was used. In this lab the equation REELED V LED / ‘LED was used. REELED = V LED / ILL-D = 2. 18 v 10. 0175 ma = 124. 7 Q To calculate the total current that the power supply was providing to the two ranches, the equation II = IR + AIR was used. In this lab the equation that was given to use was LIED = IR . Example: LIED + I LED = II . 0175 + . 0058 = . 0233 Simulation Results: Multi was used to perform the simulations. Figures 4, 5, 6 and 7 shown the results obtained in the simulations. Table 1 summarizes these results. Figure 4. Power supply= 8 volts: Voltages measured across RI and OR and currents through each LED Figure 5 . Power supply= 6 volts: Voltages measured across RI and OR and Figure 6.
Power supply= 4 volts: Voltages measured across RI and OR and Figure 7. Power supply= 2 volts: Voltages measured across RI and OR and Table 1. Comparison of Pre-l_ABA simulations and actual Lab data Looking at the comparison chart above we can see that the voltage and the total current was close in value when looking at the Pre-Lab and the Actual Lab. The actual Multi simulation charts are printed and attached to this lab report. Conclusion: In conclusion when simulating the circuit in actuality or in Multi; the LED voltage, current, and brightness are affected by the decreasing of the voltage supply.
By decreasing the voltage supply the brightness of the Leeds also crease in intensity. When determining the factors that are involved in the brightness of the LED we must look at the circuit and see if the resistors and the Leeds are connected properly. We must also look at the value of the current passing through the current. To determine the current through the Leeds Ohm’s Law was applied. To find the current we malls first measure the voltage and the resistance, and then after finding those two values we divide the voltage by the resistance. Which Ohm’s Law is I (current) = V (voltage) / R (resistance).