Paper 1B study guide

Experimental skills & reasoning

A worksheet for explaining the physics behind an investigation. Your notes remain in this page and are lost on reload unless copied.

Back to Paper 1B toolkit · Original practice tasks

Use precise error language

Choose measurements that resolve the effect

For a small length, compare a ruler, caliper and micrometer against the required range and uncertainty. Read scales without parallax and check zero offsets. For temperature, consider equilibration and sensor response time; for time, consider sampling interval and trigger delay. In supplied circuit diagrams, an ammeter goes in series and a voltmeter across the component; instrument loading can change the result.

For supplied image or video data, calibrate distance with an object in the same plane, use the actual frame interval, and consider perspective and blur. For supplied count-rate data, subtract the measured background using compatible time units and retain its uncertainty. For database data, check provenance, units, selection criteria and whether the sampling is representative.

Read the graph before calculating

Direct proportionality needs a straight line through the origin within uncertainty. A straight line with a significant intercept is a linear relationship, but not direct proportionality. Curvature, turning points and changing gradients should be described over specified intervals. At a smooth maximum or minimum the tangent is horizontal; that does not mean the value is zero.

A bar chart compares categories; a histogram groups a continuous variable into adjoining bins (unequal widths require frequency density); a pie chart shows shares of a meaningful whole. A scatter graph tests paired quantities. Avoid joining noisy points as if every wiggle were a physical effect. See Graph gradient, area & prediction for rates and signed areas.

Model assumptions and diagrams

Identify which effects the model neglects and explain why they are small in this context. On a free-body diagram, include forces acting on the chosen object, label their direction and point of application, and keep velocity arrows distinct from force arrows. Resolve a vector of magnitude F at angle θ into F cos θ and F sin θ along the chosen perpendicular axes. Check whether your calculator is using degrees or radians.

Turn a vague evaluation into a useful one

Weak: “There was human error; use better equipment.” More useful: “The timing interval is short compared with variation in start/stop delay. Timing several complete cycles increases the measured interval while keeping a similar timing uncertainty, reducing percentage uncertainty per cycle.”

Support a conclusion with the model, numbers and uncertainty. Interval overlap supports compatibility under stated bounds; it does not prove a theory. Explain whether a proposed improvement reduces random scatter, changes a bias, extends the range or tests an assumption.

Answer the command, in context

For a calculation, show the relationship and substitutions. When describing, identify what changes and over which range. When explaining, connect the observation to a physical cause. When evaluating, judge the strength of evidence and limits. For a graph sketch, label axes and show the essential shape. These are study prompts, not reproduced official command-term definitions.