IPhO 2013, Експеримент — Задача 2.6. Couplings of the solar cells
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
The two solar cells can be connected in series in two different ways as shown in Fig. 2.7. There are also two different ways to connect them in parallel (not shown in the figure).
2.6 Determine which of the four arrangements of the two solar cells yields the highest possible power in the external circuit when one of the solar cells is shielded with the shielding plate (J in Fig. 2.1). Hint: You can estimate the maximum power quite well by calculating it from the maximum voltage and maximum current measured from each configuration.
Draw the corresponding electrical diagram. [1 т.]
Отговори
2.6 Set-up d with B shielded
Conclusion of the official solution (approach 1, sample measurements).
Решение
Two approaches:
Approach 1: use a constant setting of the variable resistor to simulate a constant external load.
Approach 2: use the hint given in the question and measure values of maximal and maximal independently (no variable resistor involved).
In the following only measurements for approach 1 are presented.
a.
Unshielded (adjusting for reasonable )
13.10 mA; 0.794 V; 10.4 mW
A shielded: 0.37 mA; 0.022 V
B shielded: 0.83 mA; 0.049 V
b.
like in a.
A shielded: 1.47 mA; 0.088 V
B shielded: -2.82 mA; -0.170 V
c.
like in a.
A shielded: 6.89 mA; 0.415 V
B shielded: 6.905 mA; 0.4165 V
d.
like in a.
A shielded: 7.14 mA; 0.436 V
B shielded: -7.76 mA; -0.474 V
Conclusion: Best power: Set-up d with B shielded. (Solar cell A slightly better than B).
(2.7 on next page)
Оригинал в Архива: exp2.pdf · официални решения: exp2_sol.pdf