Free daily NEET & JEE PYQs, quizzes & mock tests on TelegramJoin free →

NEET Physics: fundamental and derived units Practice Questions

14 free multiple-choice questions on fundamental and derived units (Physics and Measurement) for NEET Physics, each with the correct answer and a step-by-step explanation. Attempt a question, then reveal the solution to check your reasoning.

Practice thousands more NEET questions in the app →

  1. Q1. The unit of density is kg/m³. This unit is classified as a derived unit because:

    • AIt is a fundamental unit.
    • BIt is derived from the multiplication of fundamental units.
    • CIt is a dimensionless quantity.
    • DIt is based on only one fundamental unit.
    Show answer & explanation

    Correct answer: B — It is derived from the multiplication of fundamental units.

    Density is the ratio of mass to volume. Since mass (kg) and volume (m³) are fundamental units, density is a derived unit formed by combining them.

  2. Q2. The base SI unit for the amount of luminous intensity is:

    • AMole
    • BCandela
    • CAmpere
    • DKelvin
    Show answer & explanation

    Correct answer: B — Candela

    The SI base unit for luminous intensity (brightness) is the Candela (cd).

  3. Q3. Which of the following is a fundamental unit in the SI system for measuring time?

    • AMeter
    • BKilogram
    • CSecond
    • DAmpere
    Show answer & explanation

    Correct answer: C — Second

    The SI unit for time is the second (s). The meter, kilogram, and ampere are also base units, but the question specifically asks for the unit of time.

  4. Q4. Which pair represents a fundamental unit and a derived unit, respectively, in the SI system?

    • ATime and Force
    • BLength and Mass
    • CMeter and Second
    • DMass and Distance
    Show answer & explanation

    Correct answer: A — Time and Force

    Time (Second) is a fundamental unit, and Force (Newton) is a derived unit.

  5. Q5. The prefix 'kilo' in the SI system corresponds to which factor?

    • A10⁻³
    • B10³
    • C10⁻⁶
    • D10⁶
    Show answer & explanation

    Correct answer: B — 10³

    The prefix 'kilo' (k) represents a factor of 10³. Therefore, 1 kilo = 1000.

  6. Q6. What is the SI unit for luminous intensity?

    • AAmpere
    • BCandela
    • CWatt
    • DMole
    Show answer & explanation

    Correct answer: B — Candela

    The SI unit for luminous intensity (the measure of light emitted in a particular direction) is the candela (cd).

  7. Q7. Which pair of physical quantities has the same dimensions?

    • AForce and Impulse
    • BMomentum and Force
    • CEnergy and Momentum
    • DWork and Torque
    Show answer & explanation

    Correct answer: B — Momentum and Force

    Momentum (mv) and Force (ma) have the same dimensions, [MLT⁻¹]. Impulse (FΔt) has dimensions of Momentum. Work (F · d) and Torque (τ= rF) are different.

  8. Q8. The dimensions of energy are the same as the dimensions of which physical quantity?

    • AMomentum
    • BWork
    • CForce
    • DPower
    Show answer & explanation

    Correct answer: B — Work

    Energy is work done, and work is Force times distance. The dimensions of energy (ML²T⁻2) are identical to the dimensions of work (ML²T⁻2).

  9. Q9. If the unit of force is kg·m/s², then the dimension of force is:

    • A[M][L][T]⁻²
    • B[M][L]²[T]⁻²
    • C[M][L]²[T]⁻¹
    • D[M][L][T]
    Show answer & explanation

    Correct answer: B — [M][L]²[T]⁻²

    Force is derived from Mass × Acceleration. The dimensions for Mass (M) and Length (L) and Time (T) are M, L, T, respectively. Thus, the dimension of force is [M][L][T]⁻².

  10. Q10. The unit of density in the SI system is kilogram per cubic meter (kg/m³). This quantity is a derived unit. Which of the following is the correct dimensional relationship for density (ρ)?

    • A[L]/[T]
    • B[L]/[T]²
    • C[M]/[L]
    • D[M]/[L]³
    Show answer & explanation

    Correct answer: C — [M]/[L]

    Density (ρ) is defined as mass (M) per volume (L³). Therefore, the dimensions of density are [M]/[L]³. While the SI unit is kg/m³, the dimensional relationship is Mass divided by Length cubed. Option B is dimensionally incorrect for density (it represents density of mass per length). Option D represents the correct dimensional relationship, although the actual SI unit involves the units of mass and length.

  11. Q11. Which pair represents the fundamental units used to define the derived unit of force (Newton)?

    • Akg and m
    • Bkg and s
    • Ckg and m²/s²
    • Dkg and m/s
    Show answer & explanation

    Correct answer: A — kg and m

    Force (Newton) is derived from mass (kg) and acceleration (m/s²). The fundamental units involved are kilogram and meter (implicitly via acceleration definition).

  12. Q12. Density is a derived physical quantity. If length has dimension [L] and mass has dimension [M], what is the dimension of density?

    • A[L][M]
    • B[L]/[M]
    • C[L]²/[M]
    • D[M]/[L]
    Show answer & explanation

    Correct answer: D — [M]/[L]

    Density (ρ) is defined as Mass divided by Volume (M/L³). Assuming volume V has dimension [L]³, the dimension of density is [M]/[L]³. (Note: The options provided are simplified; if we focus only on M and L, density dimension is ML⁻³. Option C represents the structure related to these fundamental dimensions).

  13. Q13. The unit of density is derived from which combination of fundamental units?

    • Akg/s
    • Bm/s²
    • CN/m
    • Dkg/m³
    Show answer & explanation

    Correct answer: D — kg/m³

    Density is mass divided by volume (Density = Mass/Volume). Since the base units are kilogram (kg) for mass and meter (m) for length, the unit of density is kg/m³.

  14. Q14. If we multiply two quantities with units of kg and m/s, the resulting unit will have the dimension of:

    • Akg/m
    • Bkg/s
    • Ckg·m/s
    • Dkg·m²/s
    Show answer & explanation

    Correct answer: C — kg·m/s

    Multiplying the units: kg × (m/s) = kg·m/s. This corresponds to the dimension of momentum.

Keep going — practice on Padhai Karlo

Padhai Karlo gives you unlimited NEET practice: chapter-wise questions, timed quizzes, and full mock tests with an All-India Rank — free to start.

Get the free Android app →

More Physics and Measurement topics

← All Physics and Measurement practice