AP Physics C: E&M Experimental Design FRQ Practice
41 Experimental Design and Analysis questions written in the AP format. Pick one, read the lab setup and data, and write your response.
Your first scored response is included. A plan unlocks unlimited scoring.
41 questions
sorted by unit
Dielectric permittivity measurement and analysis
Unit 8: Electric Charges, Fields, and Gauss's Law
A student is asked to determine the electric permittivity of an unknown dielectric material by measuring the electric field between two oppositely charged parallel conducting plates separated by a fixed distance.
Describe a procedure for collecting data that would allow the student to determine the relative permittivity κ of the dielectric slab. Your procedure should include (i) what quantities will be measured and how each will be measured using the available equipment, and (ii) at least one specific method for reducing experimental uncertainty (for example, multiple trials and averaging or systematic variation of an independent variable).
Describe how the collected data could be graphed and how that graph would be analyzed to determine κ. In your description, include a mathematical expression that relates the graph's slope (or slopes) to κ. Assume the electric field magnitude between the plates is E = V/d in air and E = V/(κd) when the dielectric fills the space.
Figure 1. Parallel-plate apparatus with sphere
Figure 2. Apparatus with dielectric slab
Figure 3. Blank grid for graphing
V (V) | θ_air (deg) | θ_d (deg) |
|---|---|---|
100 | 7.1 | 5.2 |
200 | 14.0 | 10.4 |
300 | 20.5 | 15.6 |
400 | 26.3 | 20.6 |
500 | 31.6 | 25.5 |
The student performs trials both with air between the plates and with the dielectric slab inserted as shown in Figure 2. For each applied potential difference V, the student measures the equilibrium angle θ of the suspended charged sphere relative to the vertical. The plate separation is d = 0.020 m and the sphere's mass is m = 0.0150 kg. The measured angles are shown in Table 1.
Indicate two quantities, either measured quantities from Table 1 or additional calculated quantities, that could be graphed to produce a straight line that could be used to determine κ.
Vertical axis: Horizontal axis:
On the grid provided in Figure 3, create a graph of the quantities indicated in part C(i).
Use Table 2 to record the measured or calculated quantities that you will plot.
Clearly label the axes, including units as appropriate.
Plot the points you recorded in Table 2.
Draw a best-fit line for the data graphed in part C(ii).
Using the best-fit line that you drew in part C(iii), calculate an experimental value for the relative permittivity κ of the dielectric slab. In your calculation, determine the slope using two points on your best-fit line and use a mathematical relationship that connects that slope to κ.
What the Experimental Design FRQ asks
The Experimental Design and Analysis question is FRQ 3 on the AP Physics C: E&M exam. You plan a lab to find an electrical or magnetic quantity, explain how to graph the data, then graph a data table and use a best-fit line to calculate the value.
- 25–30 min
- suggested on the exam
- 10 points
- across parts A to D
- 95 min
- for all four FRQs
Part A: Procedure
Describe how to collect data with the equipment provided
2 pts
Part B: Analysis plan
Describe what to graph and how the graph gives the quantity
2 pts
Part C: Graph
Choose two quantities, graph the data table, and draw a best-fit line
4 pts
Part D: Experimental value
Calculate the quantity from your best-fit line
2 pts
How Experimental Design FRQ practice works
Each question follows the exam’s format, from the full prompt to a score on every part.
Read the setup and data
The lab scenario, the equipment, the data table, and parts A through D, laid out the way the exam shows them.
Write on a 27-minute timer
Inside the 25 to 30 minutes the exam suggests for this question. Pause it or turn it off, and your response saves as you go.
Submit for a score out of 10
Your response is scored against the scoring guidelines written for that question. Your first score is included.
Feedback on every part
A summary at the top tells you what to work on next. Below it, each part shows whether you earned the point and what the scoring guidelines were looking for.
Detailed Feedback
Part A: 1/1 point
Earned the point. You correctly described a procedure to measure current with the ammeter and magnetic field with the Hall-effect sensor, and specified varying the current to collect multiple data points.
Part A: 1/1 point
Earned the point. You correctly identified repeating measurements and taking the average as a method to reduce experimental uncertainty.
Part C: 0/1 point
Did not earn the point. You left this part blank. To earn the point, you needed to indicate the quantities to be graphed on the vertical and horizontal axes (e.g., B and I).
Questions about the Experimental Design FRQ
How many responses can I get scored?
You can read every question without a plan. Your first scored response is included. A plan unlocks unlimited scoring.
Do I need to have done the lab before?
No. The question describes the setup and the equipment you can use, and gives you a data table to graph in part C.
What should I plot?
Two quantities that give a straight line, so the slope or intercept leads to the value you need. Part C asks you to name them before you graph.
How do I make the graph?
Use the drawing tool to plot the data on the grid and draw a best-fit line. You can also graph on paper, switch to handwrite, and add a photo of your page.
Are these real College Board questions?
No. We wrote them in the AP format, with the same four parts, and wrote scoring guidelines for each one.
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AP Physics C: E&M FRQs
Every FRQ type for AP Physics C: E&M, with practice for each.
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