Physics and Measurement — NEET Physics MCQs with answers

Physics and Measurement is a Class 11 Physics chapter in the NEET (UG) syllabus. NEET720 has 556 reviewed practice questions on it, each with a quick answer and a step-by-step explanation. The 8 questions below are free and fixed, so you can bookmark this page; the full chapter, plus mistake tracking and spaced revision, is in the app.

Topics covered

SI units and systems of measurement · Dimensional analysis and applications · Errors and significant figures · Accuracy, precision and least count · Instruments and least count · Units and unit systems · Order of magnitude · Dimensional Analysis · Unit Conversion · Error Analysis · Significant Figures · Dimensions · Vernier calipers · Units and dimensions · Vectors · Errors in Measurement · Dimensional Analysis · Instruments · Vernier caliper · Screw gauge · Unit systems · Simple pendulum · Significant figures · Error propagation · Units · Error analysis

8 free Physics and Measurement practice questions with answers

Choose an answer in your head before opening it. Each explanation says why the correct option is right and, where relevant, why the tempting wrong option is wrong.

1. Question 1 · medium · Errors and significant figures

   Four students each measure the same time interval three times. Their readings (in seconds) are: Student P: 4.0, 4.8, 4.4 Student Q: 4.4, 4.6, 4.2 Student R: 4.1, 4.9, 4.5 Student S: 4.4, 4.5, 4.3 Whose data show the smallest random error?

   • A.Student P
   • B.Student Q
   • C.Student R
   • D.Student S
   Show answer and explanation

   Answer: D. Student S

   Random error shows up as scatter. The spreads are P: 0.8 s, Q: 0.4 s, R: 0.8 s, S: 0.2 s. Student S's readings cluster most tightly, so S has the smallest random error.

   Random error is judged by the dispersion of repeated readings about their own mean, not by where the mean lies. Compute each range (max - min): P: 4.8 - 4.0 = 0.8 s; Q: 4.6 - 4.2 = 0.4 s; R: 4.9 - 4.1 = 0.8 s; S: 4.5 - 4.3 = 0.2 s. S's scatter is smallest, so S's measurements are the most precise (smallest random error). Note that all four means are 4.4-4.5 s: closeness of the mean to anything says nothing about random error, which is why options A and C tempt students who look at central values instead of spread.

   Common mistake: Judging random error from the mean value instead of the spread

2. Question 2 · easy · Errors and significant figures

   Which rule correctly states when a zero is counted as a significant figure?

   • A.A zero to the left of the first non-zero digit is always significant.
   • B.A zero between two non-zero digits is always significant.
   • C.A trailing zero after the decimal point is never significant.
   • D.Zeros are significant only if the number is written in scientific notation.
   Show answer and explanation

   Answer: B. A zero between two non-zero digits is always significant.

   Zeros sandwiched between non-zero digits (e.g. the 0 in 105) are always significant. Leading zeros are never significant; trailing zeros after a decimal point are always significant.

   The significant-figure rules for zero are: (i) leading zeros (before the first non-zero digit) merely locate the decimal point and are never significant; (ii) captive zeros, i.e. zeros between two non-zero digits, are always significant; (iii) trailing zeros are significant only if the number has an explicit decimal point (e.g. 100.0 has 4 sig figs, but 100 is ambiguous). Option B correctly states the captive-zero rule, which holds unconditionally.

   Common mistake: Treating all zeros the same way instead of applying the leading/captive/trailing distinction

3. Question 3 · easy · Accuracy, precision and least count

   The closeness of several repeated measurements to ONE ANOTHER is called:

   • A.precision
   • B.accuracy
   • C.least count
   • D.systematic error
   Show answer and explanation

   Answer: A. precision

   Precision = mutual agreement (small scatter) of repeated readings. Accuracy = closeness of the result to the true value. The two are independent properties.

   Precision measures reproducibility: if repeated readings cluster tightly, the measurement is precise, regardless of where the cluster sits. Accuracy measures correctness: how close the result lies to the accepted true value. A measurement can be precise but inaccurate (tight cluster, wrong place — typically a systematic error) or accurate but imprecise (readings scattered widely around the right value). Least count is an instrument property that limits precision but is not itself precision.

   Common mistake: Using 'accuracy' and 'precision' interchangeably

4. Question 4 · medium · Accuracy, precision and least count

   Which statement correctly contrasts systematic and random errors?

   • A.Random errors can be completely eliminated by sufficiently careful experimental design.
   • B.Systematic errors are effectively reduced by averaging a large number of readings.
   • C.Systematic errors act in a fixed direction and can be corrected once their cause is identified, while random errors vary unpredictably and are only reduced by averaging.
   • D.The zero error of an instrument is a typical random error.
   Show answer and explanation

   Answer: C. Systematic errors act in a fixed direction and can be corrected once their cause is identified, while random errors vary unpredictably and are only reduced by averaging.

   Systematic errors are one-directional biases (zero error, calibration fault, personal bias) — identifiable and correctable. Random errors fluctuate in sign and size — never removable, only reduced by averaging.

   The two error families differ in behaviour and in remedy. Systematic: same sign and size every time (faulty calibration, zero error, consistently warm instrument); invisible in the scatter of data, but once diagnosed, it can be corrected or subtracted out. Random: unpredictable in sign and magnitude (reaction time jitter, fluctuating conditions); visible as scatter, incorrigible individually, but the mean improves as more readings are averaged. Options A, B, D each attach the wrong remedy or the wrong classification: averaging fixes only random errors, and a zero error is the textbook systematic example.

   Common mistake: Believing averaging cures systematic errors

5. Question 5 · medium · Accuracy, precision and least count

   While timing a pendulum with a stopwatch, a student's start/stop reaction time varies unpredictably from trial to trial. The most effective way to reduce the resulting error in the period is to:

   • A.Repeat the timing many times (and time many oscillations per trial), then average.
   • B.Apply a fixed zero-error correction to every stopwatch reading.
   • C.Take one single reading with maximum possible concentration.
   • D.Recalibrate the stopwatch against a standard clock.
   Show answer and explanation

   Answer: A. Repeat the timing many times (and time many oscillations per trial), then average.

   Variable reaction time is a random error: it changes sign and size unpredictably. Averaging many trials — and dividing the watch/reaction error over many oscillations per trial — is the standard remedy.

   The error described fluctuates from trial to trial, which classifies it as random. Random errors partially cancel when readings are averaged, and timing N oscillations in one run further divides the start/stop error by N when computing one period. Corrections and calibrations (options B and D) are the right tools for systematic errors — a stopwatch that runs uniformly fast, or an offset zero — but are useless against unpredictable scatter. A single 'super-careful' reading (option C) is a gambler's strategy: it has no mechanism for cancelling the fluctuation it happens to contain.

   Common mistake: Prescribing calibration or corrections for a random error

6. Question 6 · easy · SI units and systems of measurement

   Which of the following is an SI base unit?

   • A.newton
   • B.candela
   • C.joule
   • D.coulomb
   Show answer and explanation

   Answer: B. candela

   The seven SI base units are metre, kilogram, second, ampere, kelvin, mole and candela. The candela (luminous intensity) is the only base unit listed; newton, joule and coulomb are all derived.

   SI defines exactly seven base units: metre (length), kilogram (mass), second (time), ampere (electric current), kelvin (temperature), mole (amount of substance) and candela (luminous intensity). Every other unit is built from these. The newton is kg m s^-2, the joule is kg m^2 s^-2, and the coulomb is A s — all derived. Note the common trap: SI picks the ampere, not the coulomb, as the electrical base unit, even though charge feels more 'basic' than current.

   Common mistake: Assuming the unit of any 'fundamental-feeling' quantity (force, energy, charge) must be a base unit

7. Question 7 · medium · SI units and systems of measurement

   Which statement about SI base units is correct?

   • A.The gram is the SI base unit of mass.
   • B.All SI base units are still defined by comparison with physical artefacts kept at Sevres.
   • C.The mole and the candela are derived units.
   • D.The kilogram is the only SI base unit whose name contains a prefix.
   Show answer and explanation

   Answer: D. The kilogram is the only SI base unit whose name contains a prefix.

   Uniquely among the seven base units, the kilogram carries the prefix 'kilo' in its name — yet it, not the gram, is the base unit of mass.

   The seven SI base units are m, kg, s, A, K, mol and cd. For historical reasons the base unit of mass was chosen as the kilogram, making it the only base unit whose name includes an SI prefix (this is why multiples of mass are formed from the gram: mg, g, not 'kilo-kilogram'). Option A inverts this fact. Option B is obsolete: since 20 May 2019 all base units are defined via exact values of constants (e.g. the kilogram via Planck's constant h), and the platinum-iridium prototype no longer defines anything. Option C is false — mole and candela are base units.

   Common mistake: Believing the gram is the base unit because its name has no prefix

8. Question 8 · easy · SI units and systems of measurement

   Which of the following is a correct SI base quantity–unit–symbol triple?

   • A.Luminous intensity — candela — cd
   • B.Force — newton — N
   • C.Amount of substance — kilogram — kg
   • D.Electric charge — ampere — A
   Show answer and explanation

   Answer: A. Luminous intensity — candela — cd

   The seven SI base quantities are length (m), mass (kg), time (s), electric current (A), thermodynamic temperature (K), amount of substance (mol) and luminous intensity (cd). Only option A pairs a base quantity with its correct base unit and symbol.

   SI has exactly seven base quantities, each with one base unit: length–metre (m), mass–kilogram (kg), time–second (s), electric current–ampere (A), thermodynamic temperature–kelvin (K), amount of substance–mole (mol), luminous intensity–candela (cd). Checking the options: (A) luminous intensity–candela–cd is exactly this list, so it is correct. (B) force is a derived quantity (F = ma), and its unit newton is a derived unit, not a base unit. (C) mixes up amount of substance (correctly measured in mole) with mass; kilogram is the base unit of mass, not amount of substance. (D) electric charge is derived (Q = It); its SI unit is the coulomb, while ampere is the base unit of current, a different quantity.

   Common mistake: Assuming familiar derived units like newton or coulomb are base units because they are commonly used

Questions about Physics and Measurement for NEET

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Questions are original NEET720 compositions reviewed for correctness, syllabus fit and option quality. Counts update as the bank grows (556 active practice questions in this chapter today).