Practice Test I
Physics Practice – Learn by Doing
Choose the correct option and see instant feedback
Unit of Reduction Factor
The unit of reduction factor is:
The reduction factor is related to electrical resistance, measured in Ohms.
Lumen as a Unit
Lumen is the unit of:
Lumen measures the total visible light emitted by a source per second.
Young’s Modulus – Units
Definition: Young’s modulus measures the stiffness of a material and has the same units as stress: Nm-2 (Pascal).
Q: Which one of the following is not a unit of Young’s modulus?
Young’s modulus is stress/strain, so it always has units of pressure (Nm-2).
Conversion of Young’s Modulus
Q: Young’s modulus of a wire is 18 × 1011 dyne cm-2. Convert it to SI units:
Precision of Measurement
Definition: Precision refers to the resolution of measurement, independent of accuracy.
Q: Which of the following measurement is most precise?
Smaller unit + more significant figures = higher precision.
Significant Figures
Definition: Significant figures show how precisely a number is expressed. Scientific notation preserves these figures.
Q: The significant figures for 23.023, 0.0003, and 2.1 × 10-3 are:
Screw Gauge Measurement
Definition: A screw gauge measures small dimensions with high accuracy using pitch and circular scale divisions.
Q: A student measures the diameter of a steel ball with a screw gauge (LC = 0.001 cm). MSR = 5 mm, CSR = 25 divisions, Zero error = -0.004 cm. Find the correct diameter.
Diameter = (0.5 + 0.025) - (-0.004) = 0.521 cm
Percentage Error in Volume
Definition: Error in volume is proportional to three times the error in radius (since V ∝ r³).
Q: If error in radius = 2%, error in volume = ?