Съдържание

IPhO 2013, Експеримент — Задача 2.4. Maximum power for a solar cell

Оригинал на условието (PDF)Съобщи за грешка

Всички материали от IPhO 2013

Solar cells — E2 · 7 юли 2013 г.

Warnings and notices

WARNING: Do not use the multimeter as an ohmmeter on the solar cells since the measuring current can damage them. When changing the measuring range on the multimeters, please turn the dial with caution. It can be unstable and may break. Check whether there is a number under the decimal point when measuring – if the dial is not fully in place, the multimeter will not measure, even if there are digits in the display.

Notice: Do not change the voltage on the power supply. It must be 12 V throughout the experiment. (The power supply for the light source should be connected to the outlet (230 V ~) at your table.)

Notice: Uncertainty considerations are only expected when explicitly mentioned.

Notice: All measured and calculated values must be given in SI units.

Notice: For all measurements of currents and voltages in this experiment, the LED-light source is supposed to be on.

Условие

2.4a The maximum power that the solar cell can deliver to the external circuit is denoted $P_{\max}$ . Determine $P_{\max}$ for your solar cell through a few, suitable measurements. (You may use some of your previous measurements from question 2.2). [0,5 т.]

2.4b Estimate the optimal load resistance $R_{\mathrm{opt}}$ , i.e. the total external resistance when the solar cell delivers its maximum power to $R_{\mathrm{opt}}$ . State your result with uncertainty and illustrate your method with suitable calculations. [0,5 т.]

Отговори

Решение

I	U	P
mA	V	mW
26.8	0.458	12.2744	1
27.8	0.454	12.6212	2
29.2	0.435	12.7020	3
30.6	0.410	12.5460	4
31.1	0.395	12.2845	5

P_{\max} = (12.7 \pm 0.1)\mathrm{mW}\ \text{at}\ I = (28.8 \pm 0.2)\mathrm{mA}

Hand-drawn graph on millimetre paper of power P (mW, ticks 12 and 13) against current I (mA, ticks 26 to 31) with five numbered points on a curve that peaks near 29 mA, the maximum marked with an error cross; the table of the five points (I, U, P) is printed in the upper right corner of the graph.

R_{\mathrm{opt}} = \frac{P_{\max}}{I_{\mathrm{opt}}^2} = \frac{12.71\mathrm{mW}}{(28.8\mathrm{mA})^2} = (15.3 \pm 0.3)\Omega

Оригинал в Архива: exp2.pdf · официални решения: exp2_sol.pdf