IB Physics Quiz: Experimental Techniques
8 questions · exam conditions
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Experimental TechniquesQuestion 1 of 8

A student measures the period of a pendulum by timing 20 complete oscillations and dividing by 20. To improve the precision of the measurement, which combination of modifications would be most effective?

Increase the number of oscillations timed and use a stopwatch with higher resolution
Decrease the amplitude of oscillation and measure the length more accurately
Use a heavier bob and ensure the pendulum swings in a perfect vertical plane
Repeat the measurement at different times of day and average the results
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IB Physics Quiz

IB Physics Quiz: Experimental Techniques

Practice Experimental Techniques in IB Physics with focused quiz questions that help you check what you know, review explanations, and build confidence with test-style prompts.

What this quiz covers

This quiz focuses on Experimental Techniques, giving you a quick way to practice the rules, question types, and explanations that matter most for IB Physics.

How to use this quiz

Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

All questions

Question 1

A student measures the period of a pendulum by timing 20 complete oscillations and dividing by 20. To improve the precision of the measurement, which combination of modifications would be most effective?

  1. Increase the number of oscillations timed and use a stopwatch with higher resolution (correct answer)
  2. Decrease the amplitude of oscillation and measure the length more accurately
  3. Use a heavier bob and ensure the pendulum swings in a perfect vertical plane
  4. Repeat the measurement at different times of day and average the results
Explanation: Precision refers to the reproducibility of measurements. Timing more oscillations reduces the relative uncertainty in timing, and a higher resolution stopwatch reduces instrumental uncertainty. Both directly improve precision. B addresses accuracy more than precision. C affects the physics but not measurement precision. D addresses random variations but is less effective than the fundamental improvements in A.

Question 2

In a calorimetry experiment, a student records the temperature every 30 seconds before, during, and after mixing hot and cold water. The data shows a gradual temperature rise before mixing and a gradual fall after reaching maximum temperature. What is the most appropriate method to determine the actual temperature change due to mixing?

  1. Use the difference between the highest recorded temperature and the initial temperature of cold water
  2. Extrapolate the pre-mixing and post-mixing temperature trends to the mixing time and use their difference (correct answer)
  3. Average all temperatures before mixing and subtract from the average of all temperatures after mixing
  4. Use the difference between maximum temperature and the temperature recorded immediately before mixing
Explanation: Extrapolation compensates for heat losses to the environment both before and after mixing, giving the true temperature change due to mixing alone. A ignores heat loss trends. C doesn't account for the systematic temperature changes due to heat loss. D only partially corrects for heat loss (before mixing) but ignores the cooling trend after mixing.

Question 3

A student uses a micrometer to measure the diameter of a wire and records five readings: 0.847 mm, 0.849 mm, 0.846 mm, 0.851 mm, 0.848 mm. The micrometer has a stated uncertainty of ±0.002 mm. How should the final result be reported?

  1. (0.848±0.002) mm(0.848 \pm 0.002) \text{ mm} (correct answer)
  2. (0.848±0.003) mm(0.848 \pm 0.003) \text{ mm}
  3. (0.8482±0.0020) mm(0.8482 \pm 0.0020) \text{ mm}
  4. (0.848±0.001) mm(0.848 \pm 0.001) \text{ mm}
Explanation: The mean is 0.8482 mm, rounded to 0.848 mm to match the precision of individual measurements. The uncertainty should be the larger of the instrumental uncertainty (±0.002 mm) and the standard error of the mean. The standard error is much smaller than the instrumental uncertainty, so ±0.002 mm is used. B overestimates uncertainty. C uses too many significant figures. D underestimates uncertainty.

Question 4

In a photoelectric effect experiment, a student varies the frequency of incident light and measures the maximum kinetic energy of emitted photoelectrons. To establish a reliable linear relationship between frequency and kinetic energy, which experimental consideration is most critical?

  1. Ensuring the light intensity remains constant across all frequency measurements
  2. Calibrating the energy detector to account for the efficiency variation with electron energy
  3. Maintaining the same angle of incidence for light hitting the photocathode surface
  4. Using monochromatic light sources and accounting for any stray light contamination (correct answer)
Explanation: The photoelectric effect demonstrates Einstein's quantum theory: when light hits a metal surface, electrons are emitted with maximum kinetic energy given by Ek=hf−ϕE_k = hf - \phi, where hh is Planck's constant, ff is frequency, and ϕ\phi is the work function. This equation predicts a perfectly linear relationship between frequency and kinetic energy. The correct answer is D because establishing this linear relationship requires precise frequency control. Monochromatic light ensures you're testing exactly one frequency at a time, while stray light contamination introduces unwanted frequencies that would add extra photoelectrons with different energies. This contamination would scatter your data points and obscure the clean linear relationship you're trying to measure. Let's examine why the other options are less critical: A is incorrect because while constant intensity affects the number of photoelectrons emitted, it doesn't change their maximum kinetic energy, which depends only on frequency according to Einstein's equation. B addresses measurement accuracy but isn't the most fundamental concern—even with some detector inefficiency, you'd still observe the linear trend. C is wrong because the photoelectric effect's energy relationship is independent of light's angle of incidence; the photon energy depends solely on frequency, not direction. For IB Physics photoelectric questions, remember that frequency determines the energy per photon (and thus maximum kinetic energy), while intensity only affects the number of photons. When experimental design questions ask about establishing relationships, focus on controlling the independent variable precisely—in this case, ensuring pure, well-defined frequencies.

Question 5

A student measures the time for a ball to fall from rest through different heights and plots hh versus t2t^2 expecting a linear relationship from h=12gt2h = \frac{1}{2}gt^2. The graph shows a good linear fit, but the y-intercept is 0.15 m instead of zero. What is the most likely experimental issue?

  1. The timing device has a systematic delay, causing all time measurements to be consistently late
  2. The ball was not released from rest but had an initial downward velocity
  3. Air resistance is significant, affecting the acceleration throughout the fall
  4. The reference point for measuring height was not set at the point of release (correct answer)
Explanation: This problem tests your understanding of kinematic equations and how experimental setup affects graphical analysis. When you see questions about unexpected y-intercepts in physics graphs, think about what each axis represents and what could systematically shift your measurements. The equation h=12gt2h = \frac{1}{2}gt^2 predicts that a graph of height versus time-squared should pass through the origin when the ball starts from rest at the reference height. A positive y-intercept of 0.15 m means that when t2=0t^2 = 0 (at the moment of release), the graph indicates the ball was already 0.15 m below the zero reference point. Option D is correct because if the student set their height reference point 0.15 m above the actual release point, all height measurements would be systematically increased by this amount. The ball would appear to start at +0.15 m rather than zero, creating exactly this y-intercept. Option A is wrong because timing delays would shift time measurements, not create a height offset. The relationship would remain linear through the origin, just with different slope. Option B is incorrect because an initial downward velocity would add a v0tv_0t term to the equation, making it non-linear in t2t^2 and typically creating a curved relationship, not a linear one with different intercept. Option C fails because significant air resistance would create a curved, not linear, relationship as acceleration decreases with increasing speed. Remember: When analyzing unexpected intercepts in kinematic graphs, always check whether your measurement reference points align with the assumptions in your theoretical equation.

Question 6

A student investigates how the resistance of a wire varies with temperature by passing different currents through it and measuring voltage and temperature. To minimize systematic errors, which procedure is most important?

  1. Use the same ammeter and voltmeter for all measurements to ensure consistency
  2. Allow the wire to reach thermal equilibrium before taking each measurement (correct answer)
  3. Take measurements with both increasing and decreasing current to check for hysteresis
  4. Calibrate the thermometer against a standard before beginning the experiment
Explanation: If thermal equilibrium isn't reached, the measured temperature won't correspond to the actual wire temperature, creating a systematic error in the relationship being investigated. A ensures consistency but doesn't address systematic errors. C checks for path-dependent effects but thermal equilibrium is more fundamental. D improves accuracy but thermal equilibrium is essential for valid data.

Question 7

In an experiment measuring the acceleration due to gravity using a pendulum, a student obtains g = 9.65 m/s² with an uncertainty of ±0.15 m/s². The accepted value is 9.81 m/s². Which statement best evaluates this result?

  1. The result is accurate because the percentage error is less than 2%
  2. The result is precise but not accurate since it differs from the accepted value
  3. The result shows reasonable agreement with the accepted value considering typical experimental limitations (correct answer)
  4. The result is both accurate and precise since the uncertainty is relatively small
Explanation: The measured value (9.65 ± 0.15) ranges from 9.50 to 9.80 m/s², while the accepted value is 9.81 m/s². Although the accepted value falls just outside the uncertainty range, this represents reasonable agreement for a pendulum experiment, which typically has systematic errors from air resistance, finite amplitude, and other factors. A focuses only on percentage error without considering experimental context. B incorrectly assumes the difference is definitively significant. D makes claims about precision without multiple measurement data.

Question 8

A student designs an experiment to test whether the frequency of a tuning fork changes with temperature. The setup includes a tuning fork, a microphone connected to a frequency analyzer, and a controlled temperature chamber. What is the most significant potential source of systematic error?

  1. Random fluctuations in the frequency analyzer's digital display during measurement
  2. The microphone picking up background noise and harmonics from the tuning fork
  3. Temperature gradients within the chamber causing non-uniform heating of the tuning fork (correct answer)
  4. Variations in the striking force used to excite the tuning fork at different temperatures
Explanation: Temperature gradients would cause systematic errors because different parts of the tuning fork would be at different temperatures, affecting the measurement in a consistent, predictable way. A describes random error. B could introduce systematic error but is less fundamental to the experimental design. D could cause systematic error but is more easily controlled than temperature uniformity.