Simple Circuits AP Physics 2 FRQ – Exam Style Questions etc.
Simple Circuits AP Physics 2 FRQ
Unit 11: Electric Circuits
Weightage : 15–18%
Exam Style Practice Questions , Simple Circuits AP Physics 2 FRQ
Question: (12 points, suggested time 25 minutes)
A group of students prepare a large batch of conductive dough (a soft substance that can conduct electricity) and then mold the dough into several cylinders with various cross-sectional areas A and lengths l. Each student applies a potential difference ΔV across the ends of a dough cylinder and determines the resistance R of the cylinder. The results of their experiments are shown in the table below.
(a) The students want to determine the resistivity of the dough cylinders.
i. Indicate below which quantities could be graphed to determine a value for the resistivity of the dough cylinders. You may use the remaining columns in the table above, as needed, to record any quantities (including units) that are not already in the table.
Vertical Axis: ________________________ Horizontal Axis: ________________________
ii. On the grid below, plot the appropriate quantities to determine the resistivity of the dough cylinders. Clearly scale and label all axes, including units as appropriate.
iii. Use the above graph to estimate a value for the resistivity of the dough cylinders.
(b) Another group of students perform the experiment described in part (a) but shape the dough into long rectangular shapes instead of cylinders. Will this change affect the value of the resistivity determined by the second group of students?
____ Yes ____ No
Briefly justify your reasoning.
(c) Describe an experimental procedure to determine whether or not the resistivity of the dough cylinders depends on the temperature of the dough. Give enough detail so that another student could replicate the experiment. As needed, include a diagram of the experimental setup. Assume equipment usually found in a school physics laboratory is available.
Answer/Explanation
Ans:
(a) (i)
Vertical Axis: __Resistance_______, Horizontal Axis: Length (L) / Area (A)__
(ii)
(iii)
slope = resistivity \(\frac{n3c}{tan} = \frac{105-23.c}{263.2 – 61.2} = \frac{81.4}{202}\)
= 403 Ω m
(b)
X No
Resistivity is a property of the material, not the slope it is in. Since the dough does not change, the resisting limit either.
(c)
A circuit like the one pictorial below will be set up, with the voltage serve being content, perhaps a ev Battery. An computer should be wired in series and a volt meter should be wired in parallel with the dough. This setup will allow the student to see the Resistance of the dough because voltage will be known (via battery limit of voltmeter reading) and current will be known (via computer reading), and the relationship v = IR can be used. While maintaining constant length and cross section area. the dough should be heated or cooled, or both, which can be done in a variety of ways, depending on available resources. An re meter both could cool the dough, or a hot plate could hot it up. The student should get measurements of current and voltage several times after either heating the dough up or cooling it down, as it travers a range of Temp to item to room temp while a the meter could help determine mac pearly resisting at each temp. it is not needed both it is same the dough is changing temp. The relationship Since A and l ve could, any change in R, fenot in the method desubi eaten, with signity a change on resistivity P(resisting) = \(\frac{RA}{l}\) is used now.
