* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Presentazione di PowerPoint - INFN-LNF
Electrical ballast wikipedia , lookup
Power engineering wikipedia , lookup
Variable-frequency drive wikipedia , lookup
History of electric power transmission wikipedia , lookup
Resistive opto-isolator wikipedia , lookup
Distribution management system wikipedia , lookup
Power electronics wikipedia , lookup
Current source wikipedia , lookup
Voltage regulator wikipedia , lookup
Switched-mode power supply wikipedia , lookup
Stray voltage wikipedia , lookup
Power MOSFET wikipedia , lookup
Shockley–Queisser limit wikipedia , lookup
Semiconductor device wikipedia , lookup
Voltage optimisation wikipedia , lookup
Rectiverter wikipedia , lookup
Surge protector wikipedia , lookup
Mains electricity wikipedia , lookup
Alternating current wikipedia , lookup
Measurement of Planck’s constant Francesco Gonnella Matteo Mascolo Our experiment • The goal of our experiment is to give an estimation of Planck’s constant; • With our experimental setup, we expect to achieve an accuracy of 10-20% The diode (1/2) “In electronics, a diode is a two-terminal electronic component with an asymmetric transfer characteristic, with low resistance to current flow in one direction, and high resistance in the other.” (Wikipedia) Silicon lattice N-doped semiconductor P-doped semiconductor The diode (2/2) A “hole” behaves exactly like an electron of positive electric charge: • Negative charges are available in the n zone • Positive charges are available in the p zone Vd I=0 Depletion zone V = 0 LED: Light Emitting Diode I≠0 I=0 V = 0 V > 0 Measuring h with a LED • If one applies enough voltage to the junction, the LED starts emitting photons having all the same frequency, f (depending only on Egap) • When the LED starts to glow, the energy E lost by every electron/hole jumping over the junction is converted to the energy of one single photon • The energy of the charges in these conditions is E = eVth where e = 1.602x10-19 C and Vth is the LED threshold voltage. • The energy of the emitted photon will be, according to Planck’s theory, is E = hf (with h Planck’s constant) …energy is conserved in the process, so: eVth = hf To-do list You must determine the threshold voltage of the LED, Vth 1) You have to change the voltage applied to the LED, writing the corresponding current flowing through the junction 1) Draw the plot “I vs V” as shown in figure 1) Extrapolate the value of V for I= 0 using a linear fit of the straight part of the data. That value is a good estimation of Vth 4) Evaluate h using the relation eVth=hf, knowing e and f (the latter is written in the LED datasheet) Experimental setup ocular LED power I/0 Measurement connectors Readout switch Power controller 12 V current voltage Pay attention to the instruments Ammeter Voltmeter Let’s get started!