The international system of units MCQ Quiz - Objective Question with Answer for The international system of units - Download Free PDF

Last updated on May 31, 2025

Latest The international system of units MCQ Objective Questions

The international system of units Question 1:

The unit of relative permittivity is 

  1. C2N-1m-2 
  2. Nm2C-2 
  3. unitless
  4. NC-2m-2 

Answer (Detailed Solution Below)

Option 3 : unitless

The international system of units Question 1 Detailed Solution

Calculation: 

The unit of relative permittivity

Relative permittivity, also known as the dielectric constant, is a dimensionless quantity. It is the ratio of the permittivity of a substance to the permittivity of free space (vacuum).

Since it is a ratio of two quantities with the same unit, the unit of relative permittivity is unitless.

∴ The correct answer is option 3

The international system of units Question 2:

Find the value of 'n' in the given equation P = ρnv2 where 'P' is the pressure, 'ρ' density and 'v' velocity.

  1. n = \(\frac{1}{2}\)
  2. n = 1
  3. n = 3
  4. n = 2

Answer (Detailed Solution Below)

Option 2 : n = 1

The international system of units Question 2 Detailed Solution

Concept Used:

The given equation is:

P = ρn v2

We need to find the value of n, and to do this, we will perform dimensional analysis. The dimensions of each quantity involved are as follows:

The dimensions of pressure P are: [P] = M L-1 T-2

The dimensions of density ρ are: [ρ] = M L-3

The dimensions of velocity v are: [v] = L T-1

Substitute these dimensions into the given equation:

[P] = [ρn] [v2]

Calculation:

Let’s plug in the dimensions:

[M L-1 T-2] = [ (M L-3)n ] [ (L T-1)2 ]

Simplify the dimensions on the right-hand side:

[M L-1 T-2] = [Mn L-3n] [L2 T-2]

Combine the terms on the right-hand side:

[M L-1 T-2] = [Mn L-3n+2 T-2]

Now, equate the exponents of corresponding dimensions from both sides:

For mass (M): 1 = n

For length (L): -1 = -3n + 2

For time (T): -2 = -2 (This is already satisfied)

From the mass dimension equation, we get:

n = 1

To verify, substitute n = 1 in the length dimension equation:

-1 = -3(1) + 2

-1 = -3 + 2

-1 = -1

This is correct, so the value of n is confirmed as:

n = 1

Therefore, the correct option is:

Option 2: n = 1

The international system of units Question 3:

Which of the following statement/statements is/are true regarding the light year?

1. Light year is a unit of distance.

2. Light is a unit of time.

3. A light year is the distance that light travels in one Earth year.

4. Light year is the measurement of light intensity

  1. Only 1 is correct
  2. Only 1 and 2 are correct
  3. Only 1 and 3 are correct
  4. Only 2 is correct

Answer (Detailed Solution Below)

Option 3 : Only 1 and 3 are correct

The international system of units Question 3 Detailed Solution

The correct answer is Option 3

Key Points

  • Light year is a unit of distance.
  • A light year is the distance that light travels in one Earth year.
  • Light year is not a unit of time or a measurement of light intensity.
  • Light travels approximately 5.88 trillion miles (9.46 trillion kilometers) in one year.

Additional Information

  • The term light year is often used in astronomy to measure vast distances between celestial objects.
  • Light year helps in expressing astronomical distances in a comprehensible way for scientific communication.
  • One light year equals approximately 63,241 astronomical units (AU), where one AU is the average distance from the Earth to the Sun.

The international system of units Question 4:

Match the following:

List - II List - II
a. Electric charge i. Farad
b. Electric field ii. Coulomb
c. Electric potential  iii. Newton/coulomb
d. Electric capacity iv. Volt

  1. a - ii, b - iii, c = iv, d - i
  2. a - iii, b - ii, c - i, d - iv
  3. a - iv, b - i, c - iii, d - i
  4. More than one of the above
  5. None of the above

Answer (Detailed Solution Below)

Option 1 : a - ii, b - iii, c = iv, d - i

The international system of units Question 4 Detailed Solution

The correct answer is a - ii, b - iii, c = iv, d - i.

The correct match:

SI Unit

Physical Quantity

Resistance

Ohms

Electric charge

Coulomb

Electric field

Newton/coulomb

Electric potential

Volt

Electric capacity Farad

The international system of units Question 5:

Which of the following is the SI unit of velocity?

  1. kg/m 
  2. kg/s
  3. m/s
  4. s/m

Answer (Detailed Solution Below)

Option 3 : m/s

The international system of units Question 5 Detailed Solution

The correct answer is m/s

Key Points

  • Velocity: The rate of change of displacement of a body is called the velocity of that body.

\(\Rightarrow Velocity=\frac{Displacment (x)}{Time (t)}\)

  • Velocity is a vector quantity that has both magnitudes as well as direction.

EXPLANATION:

  • The unit of velocity is m/s and the dimension of velocity is [M0LT-1].

Top The international system of units MCQ Objective Questions

The SI unit of work function of a metal used in photoelectric effect is

  1. joule (J)
  2. newton (N)
  3. pascal (Pa)
  4. hertz (Hz)

Answer (Detailed Solution Below)

Option 1 : joule (J)

The international system of units Question 6 Detailed Solution

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The correct answer is option 1) i.e. joule (J)

CONCEPT:

  • Work function: It is the minimum amount of energy required to cause photo-emission of electrons from a metal surface when light is incident on it.
    • The work function is also known as the threshold energy.
    • The energy of the incident light is equal to the sum of the work function and the photoelectron kinetic energy.
    • Therefore, the total energy of photon = work function + maximum kinetic energy of the electron.

The energy of a photon is given by the equation:

 \(E =hν\)

Where ν is the frequency of incident light and h is the Planck's constant.

EXPLANATION:

  • The work function is a measure of energy. All forms of energy have the same SI unit i.e. joule (J).

Candela is unit of _________.

  1. acoustic intensity
  2. electric intensity
  3. magnetic intensity
  4. luminous intensity

Answer (Detailed Solution Below)

Option 4 : luminous intensity

The international system of units Question 7 Detailed Solution

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CONCEPT:

  • The standard units of measurement defined by the ISU for the seven base quantities are SI base units.
  • All other SI units are derived from them.
  • 7 Basic SI units with their quantities: 
Fundamental Quantities
Quantities S.I unit
Mass  Kilogram(kg)
Length Meter(m)
Time second(s)
Amount of Substance Mole(mol)
Temperature Kelvin(K)
Electric Current Ampere(A)
Luminous intensity Candela(cd)

EXPLANATION:

  • From the above table, it is clear that Candela is a unit of luminous intensity. Therefore option 4 is correct. 

Important Points

  • Supplementary units: The units that are used along with base units to form derived units in the International System are called supplementary units.
Supplementary Quantities
Plane angle  radian(rad)
Solid angle steradian(Sr)
Derived Quantities
Inductance Henry (H)
Magnetic Flux Weber (Wb)
Pressure Pascal(Pa)
Power Watt(W)

'Farad' is the unit of 

  1. Resistance 
  2. Conductance 
  3. Capacitance 
  4. Inductance

Answer (Detailed Solution Below)

Option 3 : Capacitance 

The international system of units Question 8 Detailed Solution

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Concept:

Capacitance

  • Capacitance is a property of the electric conductor measured by the amount of separated electric charge that can be stored on it per unit change in electrical potential.
  • In capacitor, amount of charge, Q = CV, where, C = Capacitance, V = electrical potential
  • A capacitance in an electric circuit is introduced by a device called a capacitor.
  • The SI unit of the capacitance is Farad and is denoted by the F.

Explanation:

The SI unit of capacitance is Farad denoted by F.

Additional Information

  • Resistance
    • ​​Resistance in an electric circuit is introduced by a device called a resistor.
    • Formula, V = IR, where I = electric current flowing in the circuit, V =  supplied voltage, R = Resistance
    • The SI unit of resistance is Ohm denoted by Ω.
  • Conductance
    • ​The reciprocal of the resistance In a conductor is called conductance.
    • Relation, \(Conductance=\frac{1}{Resistance}\)
    • The SI unit of conductance is Ohm-1.
  • Inductance
    • The inductance in an electric circuit is introduced by a device called an inductor
    • The SI unit of the inductance is Henery denoted by H.

If the atmospheric pressure is given by 106 dyne/cm2, the equivalent value in its SI unit will be-

  1. 106 N/m2
  2. 105 N/m2
  3. 104 N/m2
  4. 103 N/m2

Answer (Detailed Solution Below)

Option 2 : 105 N/m2

The international system of units Question 9 Detailed Solution

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The correct answer is option 2) i.e. 105 N/m2

CONCEPT:

  • Système International (SI) unit is the metric system used for standard measurements of quantities.
    • It is also known as the MKS system.
    • This system considers metre (m) as the unit of length, kilogram (kg) as the unit of mass, and second (s) as the unit of time.
  • CGS system considers centimetres (cm) as the unit of length, gram (g) as the unit of mass, and second (s) as the unit of time.

EXPLANATION:

  • Dyne is the cgs unit for force. The SI unit of force is N.
  • cm2 is the cgs unit for the area. The SI unit for the area in m2.
  • Hence, the SI unit for atmospheric pressure is N/m2.
  • 1 dyne is equal to the force that would give a free mass of 1 g acceleration of 1 cm/s2.

⇒ 1 dyne = 1 g × 1 cm/s2

⇒ 1 dyne = 10-3 kg × 10-2 m/s2  (∵ 1 m = 100 cm and 1 kg = 1000 g)

⇒ 1 dyne = 10-5 N

⇒ 106 dyne/cm2 = \(\frac{10^{6} \times 10^{-5}N}{(10^{-2})^2m^2} = 10^5 \:N/m^2\)

In SI unit system, pascal is the unit of

  1. pressure
  2. work
  3. energy
  4. power

Answer (Detailed Solution Below)

Option 1 : pressure

The international system of units Question 10 Detailed Solution

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Explanation:

  • Force (F): The interaction which after applying on a body changes or try to change the state of rest or state of motion of a body is called force.
    • The SI unit of force is Newton (N)

Force (F) = Mass (m) × acceleration (a)

  • Pressure (P): The force per unit area is called pressure.
  • The SI unit of pressure is the pascal (Pa) 
  • It can also be written as Newton /meterthat is unit of force divided by unit of area. 
  • The other units of pressure are Bar and torr. 

Additional Information

  •  The SI units are internationally accepted units. 
  • SI unit of work and energy is Joule. 
  • SI unit of power is Watt. 

The SI base unit of electric flux is

  1. N m-2 C-1
  2. kg m3 s-3 A-1
  3. N C-1
  4. N m-1 s

Answer (Detailed Solution Below)

Option 2 : kg m3 s-3 A-1

The international system of units Question 11 Detailed Solution

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The correct answer is option 2) i.e. kg m3 s-3 A-1

CONCEPT:

  • Electric flux: It is the number of electric field lines passing through a given surface area. The electric flux associated with a surface kept in a uniform electric field is given by

ϕ = E.A = EAcosθ 

Where E is the uniform electric field, A is the area of the surface and θ is the angle between E and area vector of A.

  • The SI base units are the standard units of measurement.
    • The seven base units used in SI system are: meter (m), kilogram (kg), second (s), kelvin (K), ampere (A), mole (mol), and candela (cd).

EXPLANATION:

  • The SI unit of the electric field is N C-1 and the SI unit for area is m2. Hence the SI unit for electric flux is N m2 C-1.
  • N is the SI unit of force, which is obtained from the product of mass and acceleration. F = ma.
    • Therefore, the base units for N is kg m s-2.
  • C is the SI unit for electric charge. We know, charge = current × time. The units for current is A and time is s.
    • Therefore, the base units of C is A s

​On substituting these to N m2 C-1,

⇒ (kg m s-2) (m2) (A s)-1 = kg m3 s-3 A-1 

The physical quantities with their SI unit are given. Choose the wrong one.

  1. Force- Newton
  2. Magnetic field- Tesla
  3. Radioactivity- Becquerel 
  4. Capacitance- Volt

Answer (Detailed Solution Below)

Option 4 : Capacitance- Volt

The international system of units Question 12 Detailed Solution

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CONCEPT:

  • Force: The interaction which after applying on a body changes or try to change the state of rest or state of motion of the body is called force.
    • The SI unit of force is Newton.
  • Magnetic field: The region around a magnet or a current-carrying wire in which the magnetic force on the other magnet can be experienced is called a magnetic field.
    • The SI unit of the magnetic field is the tesla (T).
  • Radioactivity: Radioactive decay is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is considered radioactive.
    • The original unit for measuring the amount of radioactivity is the curie (Ci) – first defined to correspond to one gram of radium-226.
    • 1 curie = 3.7x1010 radioactive decays per second.
    • In the International System of Units (SI) the curie has been replaced by the becquerel (Bq).
    • 1 becquerel = 1 radioactive decay per second = 2.703x10-11 Ci.​
  • Capacitance: The capacity of a capacitor to store electric charge is called capacitance.
    • The unit of capacitance is the farad, (symbol F ).

EXPLANATION:

From the above discussion, we can say that

  • Options 1, 2, and 3 are correctly matched with their respective SI units.
  • But the SI unit of capacitance is Farad, so option 4 is wrong.

Railways Solution Improvement Satya 10 June Madhu(Dia)

SI Unit

CGS unit

Quantity

Hertz (Hz)

Hertz (Hz)

Frequency

Newton (N)

dyne (dyne)

Force

Pascal (Pa)

dyne cm-2

Pressure

Joule (J)

erg (erg)

Energy, Work

Coulomb (C)

franklin

Electric Charge

Volt (V)

statvolt

Potential Difference

Farad (F)

cm

Capacitance

Siemens (S)

abmho

Electric Conductance

Henry (H)

cm-1 s

Inductance

Ohm

Abohm

Electrical Resistance

Weber

Maxwell

Magnetic Flux

Tesla (T)

gauss (G) or oersted

Magnetic Field Strength/Magnetic field

becquerel (Bq) - Radioactivity

Henry is the unit of ?

  1. Capacitance
  2. Inductance
  3. Magnetic Intensity
  4. Frequency

Answer (Detailed Solution Below)

Option 2 : Inductance

The international system of units Question 13 Detailed Solution

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CONCEPT:

  • Induction: It is the magnetic field that is proportional to the rate of change of the magnetic field.
    • This definition of induction holds for a conductor. Induction is also known as inductance.
    • L is used to represent the inductance and Henry is the SI unit of inductance.
    • 1 Henry is defined as the amount of inductance required to produce an emf of 1 volt in a conductor when the current change in the conductor is at the rate of 1 Ampere per second.
    • Following are the factors that affect the inductance:
    1. The number of turns of the wire used in the inductor.
    2. The material used in the core.
    3. The shape of the core.
    • Electromagnetic Induction: The law was given by Faraday which states that by varying the magnetic flux electromotive force is induced in the circuit.
    • Inductance: It can be defined as the electromotive force generated to oppose the change in current at a particular time duration.

 According to Faraday’s Law:

\(E.M.F = -L\frac{\Delta I}{\Delta t}\)

\(Unit = \frac{Volts \times second}{Ampere} = Henry\)

EXPLANATION:

  • From the above discussion, it's clear that the unit of inductance is Henry.

The correct option is 2.

Additional Information

  • Unit of capacitance: Farad
  • Unit of magnetic intensity: W/m2
  • Unit of Frequency: Hertz

How many types of units exist in physics?

  1. 2
  2. 3
  3. 4
  4. 5

Answer (Detailed Solution Below)

Option 1 : 2

The international system of units Question 14 Detailed Solution

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CONCEPT:

  • Unit: The unit is the chosen standard used for measuring a physical quantity. It is also used for taking any comparisons in measurements.
    • The conversions of units allow for measurements of a property that has already recorded through different units.
    • For example, centimeters to inches.
  • Types of Unit: 
    • There are two main types of Units are present. which are as follows-
  • Fundamental units: The Fundamental Quantity is an independent Physical Quantity that cannot be expressed in terms of other Physical Quantities.
    • They are conventionally chosen.
    • It is used as a base to get other derived quantities by combining them.

There are 7 fundamental quantities.

7 FUNDAMENTAL UNITS
Physical Quantity SI unit Symbol
Length meter m
Mass Kilogram kg
Time second s
Electric current ampere A
Temperature Kelvin K
Luminous intensity Candela Cd
Amount of substance Mole mol
  • Derived Unit: The combination of two base units that means fundamental units that express a physical quantity.
    • It is presented by SI units.  For example, the velocity is the distance(m) traveled per unit time(s)
    • so we can say the derived unit of velocity is 'm/s.

EXPLANATION:

  • There are two types of units. So option 1 is correct. 

The SI unit of universal gravitational constant (G) is-

  1. Nm/kg
  2. Nm2/kg
  3. Nm2/kg2
  4. N2m2kg2

Answer (Detailed Solution Below)

Option 3 : Nm2/kg2

The international system of units Question 15 Detailed Solution

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CONCEPT:

  • Newton's law of gravitation: The gravitational force between two objects is directly proportional to the product of masses of the objects and inversely proportional to the distance between two mass.

i.e., \(F = \frac{{GMm}}{{{R^2}}}\)

whereas according to classical mechanics force acting on the particle is given as

Force (F) = mass (m) × acceleration (a)

Where, F = gravitational force, M = mass of a heavier object, m = mass of a lighter object, R = distance between two masses

EXPLANATION:

Now using the above equation, we can say that \(G = \frac{{F{R^2}}}{{Mm}}\)

The SI unit of force is the Newton (N).

The SI unit of distance (R) is meter (m) and the SI unit of mass is kg.

The SI unit of G = N m2/kg2

So option 3 is correct.

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