Physics · Science General

Units and Measurement

1,044 Questions

Master the fundamentals of physics with these practice questions on units and measurement. The topics include fundamental SI units, derived quantities, and specific units for power, force, and light. These questions are essential for building a strong foundation for competitive exams.

SI fundamental unitsUnits of powerDerived quantities unitsThermal energy unitsVolume measurement unitsElectric current units

Units and Measurement Questions

Multiple choice physics measurements and units some examples of derived units fundamental and derived quantities fundamental and derived units

Which of the following physical quantities has neither dimensions nor unit?

  1. angle

  2. Luminous intensity

  3. Coefficient of friction

  4. Current
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Unit of angle is radian, that of luminous intensity is candela and that of current is Ampere. Coefficient of friction is unitless and dimensionless.

Coefficient of friction$=\dfrac{Applied force}{Normal reaction}$
$=\dfrac{[MLT^{-2}]}{[MLT^{-2}]}=$No dimensions
Unit $=\dfrac{N}{N}=$No unit.

Multiple choice physics measurements and units some examples of derived units fundamental and derived quantities fundamental and derived units

The unit of Stefans constant $\sigma$ is:

  1. $\dfrac{{watt}^{4}}{m{K}^{4}}$
  2. $\dfrac{calorie}{{m}^{2}{K}^{4}}$
  3. $\dfrac{watt}{{m}^{2}{K}^{4}}$
  4. $\dfrac{joule}{{m}^{2}{K}^{4}}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Stefan's law states P = sigma * A * T^4. Rearranging for sigma gives P/(A * T^4), which has units of Watt/(m^2 * K^4).

Multiple choice physics measurements and units some examples of derived units fundamental and derived quantities fundamental and derived units

The SI unit of permeability of free space is

  1. $\cfrac { \text { weber } } { \text { ampere } }$
  2. $\cfrac { \text { henry } } { \text { ampere } }$
  3. $\cfrac { \text { tesla } } { \text { ampere-meter } }$
  4. $\cfrac { \text { weber } } { \text { ampere-meter } }$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The magnetic field B is related to force by F = I * L * B. Thus, B = F/(I * L) = Newton/(Ampere * meter). Since 1 Tesla = 1 Weber/m^2, the units of permeability (mu = B/H) involve Weber/(Ampere * meter).

Multiple choice physics measurements and units some examples of derived units fundamental and derived quantities fundamental and derived units

The value of Faraday number in SI unit is:

  1. $ 9.65 coulomb/kg-equivalent $
  2. $ 9.65\times 10^7 coulomb/kg-equivalent $
  3. $ 9.65\times 10^{-7} coulomb/kg-equivalent $
  4. $ 9.65 \ coulomb/g -equivalent $
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Faraday is the charge of 1 mole of electron
That is, $6.022 \times { 10 }^{ 23 } \times 1.60217646 \times { 10 }^{ -19 }\ = 9.65 \times { 10 }^{ 4 } C/g-equivalent \ = 9.65 \times { 10 }^{ 7 }C/kg-equivalent$

Multiple choice physics measurements and units some examples of derived units fundamental and derived quantities fundamental and derived units

SI unit of heat capacity is

  1. joule

  2. joule/kilogram

  3. joule/(kilogram x kelvin)

  4. joule/kelvin
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Heat capacity is a physical property of matter, defined as the amount of heat to be supplied to a given mass of a material to produce a unit change in its temperature. The SI unit for heat capacity of an object is joule per kelvin ($J/K$ or $J k^{-1}$).

Multiple choice physics measurements and units some examples of derived units fundamental and derived quantities fundamental and derived units

The SI units of mass and weight are ______

  1. kg and kg

  2. N and kg

  3. kg and N

  4. N and N
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Mass is intrinsic nature of any object or material and it doesn't vary or depend on gravitational field around it.
Weight is the force experienced by an object and it depends on both the mass as well as gravitational field which it experiences in a particular place.

Multiple choice physics measurements and units some examples of derived units fundamental and derived quantities fundamental and derived units

How watt is related to the fundamental units?

  1. kg m$^2 s^{-3}$
  2. kg m$^2 s^{-2}$
  3. Nm $s^{-1}$

  4. Nm
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

SI unit of mass is Kg , acceleration is $ms^{-2}$ ad of velocity is $ms^{-1}$.

Now power is defined as $=$ force $\times  $ velocity, where $F=m\times a$
So, $P=m\times a\times v$ , putting the SI unit of $m, a, v$
We get SI unit of power is $kgm^2s^{-3}$.