Units and Measurements

12 Questions Start DPT Test
Q1 DPT Dimensions Analysis MCQ
21 Jul 2026
Concept: Dimensional Analysis
If Gravitational force is given by $F = \frac{G M_1 M_2}{r^2}$, then find the dimensional formula (D.F.) of Gravitational constant $G$.
A.
$[M^{-1}L^3T^{-2}]$
B.
$[ML^3T^{-2}]$
C.
$[M^{-2}L^3T^{-1}]$
D.
$[M^{-1}L^2T^{-2}]$
Q2 DPT Dimensions Analysis MCQ
21 Jul 2026
Concept: The dimensional formula of a physical quantity is derived from its defining formula. For the coefficient of viscosity ($\eta$), rearranging the formula for viscous force gives $\eta = \frac{F}{6 \pi r v}$. Since $6 \pi$ is a dimensionless constant, the dimensions of $\eta$ depend on force, radius, and velocity.
Find the dimensional formula of the coefficient of viscosity $\eta$, given that the viscous force $F$ is given by $F = 6 \pi \eta r v$, where $r$ is radius and $v$ is velocity.
A.
$[M^1 L^{-1} T^{-1}]$
B.
$[M^1 L^1 T^{-1}]$
C.
$[M^1 L^{-1} T^{-2}]$
D.
$[M^1 L^1 T^{-2}]$
Q3 DPT Dimensions Analysis MCQ
21 Jul 2026
Concept: Specific heat capacity is the amount of heat energy required to raise the temperature of a unit mass of a substance by one degree Celsius or Kelvin. The relation between heat given ($\Delta Q$), mass ($M$), specific heat capacity ($S$), and rise in temperature ($\Delta T$) is given by:
$\Delta Q = M S \Delta T$
What is the dimensional formula of specific heat capacity ($S$)?
A.
$M^0 L^2 T^{-2} K^{-1}$
B.
$M L^2 T^{-2} K^{-1}$
C.
$M^0 L T^{-2} K^{-1}$
D.
$M^0 L^2 T^{-1} K^{-1}$
Q4 DPT Dimensions Analysis MCQ
21 Jul 2026
Concept: Electric charge $q$ is defined as the product of electric current $I$ and time $t$. Current is a fundamental physical quantity with dimension $[A]$, and time has dimension $[T]$.
Find the dimensional formula of charge if the formula of charge is equal to current $\times$ time.
A.
$[M^0 L^0 T^1 A^1]$
B.
$[M^1 L^0 T^{-1} A^1]$
C.
$[M^0 L^1 T^1 A^{-1}]$
D.
$[M^1 L^1 T^{-2} A^1]$
Q5 DPT Dimensions Analysis MCQ
21 Jul 2026
Concept: Electric potential ($V$) is defined as the work done ($W$) per unit electric charge ($q$). Using the relationship $V = \frac{W}{q}$, the dimensions of potential can be derived from the dimensional formulas of work done and electric charge.
Find the dimensional formula of electric potential or voltage.
A.
$[M^1 L^2 T^{-2} A^{-1}]$
B.
$[M^1 L^2 T^{-3} A^{-1}]$
C.
$[M^1 L^1 T^{-3} A^{-2}]$
D.
$[M^0 L^2 T^{-3} A^{-1}]$
Q6 DPT Dimensions Analysis MCQ
21 Jul 2026
Concept: Resistance ($R$) is defined by Ohm's law as $R = \frac{V}{I}$, where $V$ is potential difference (Voltage) and $I$ is electric current. Potential difference is the work done per unit charge, $V = \frac{W}{q}$, and charge is given by $q = I \cdot t$.
Find the dimensional formula of resistance.
A.
$[\text{M}^1\text{L}^2\text{T}^{-3}\text{A}^{-1}]$
B.
$[\text{M}^1\text{L}^2\text{T}^{-3}\text{A}^{-2}]$
C.
$[\text{M}^1\text{L}^3\text{T}^{-3}\text{A}^{-2}]$
D.
$[\text{M}^1\text{L}^2\text{T}^{-2}\text{A}^{-2}]$
Q7 DPT Dimensions Analysis MCQ
21 Jul 2026
Concept: According to Ohm's law, resistance $R$ is given by $R = \frac{V}{I}$, where $V$ is electric potential and $I$ is electric current. Electric potential is work done per unit charge, $V = \frac{W}{q}$, and charge is current multiplied by time, $q = I \cdot t$. Combining these gives $R = \frac{W}{I^2 \cdot t}$.
Find the dimensional formula of resistance.
A.
$[M^1 L^2 T^{-3} A^{-1}]$
B.
$[M^1 L^2 T^{-3} A^{-2}]$
C.
$[M^1 L^3 T^{-3} A^{-2}]$
D.
$[M^1 L^2 T^{-2} A^{-2}]$
Q8 DPT Dimensions Analysis MCQ
21 Jul 2026
Concept: Resistivity $\rho$ is calculated by rearranging the formula $R = \rho \frac{l}{\text{Area}}$ to get $\rho = \frac{R \cdot \text{Area}}{l}$. The dimensional formula of resistivity is obtained by combining the dimensions of resistance, area, and length.
If $R = \rho \frac{l}{\text{Area}}$, where $R$ is resistance, $l$ is length, and $\rho$ is resistivity, find the dimensional formula of resistivity.
A.
$[M^1 L^3 T^{-2} A^{-2}]$
B.
$[M^1 L^2 T^{-3} A^{-2}]$
C.
$[M^1 L^3 T^{-3} A^{-2}]$
D.
$[M^1 L^3 T^{-3} A^{-1}]$
Q9 DPT Dimensions Analysis MCQ
21 Jul 2026
Concept: By the principle of homogeneity of dimensions, the dimensions of both sides of a physical equation must be equal. Therefore, $[\text{Kinetic Energy}] = [\alpha] \cdot [s]^2$, which gives $[\alpha] = \frac{[\text{Kinetic Energy}]}{[s]^2}$.
Kinetic energy of a particle moving along an elliptical trajectory is given by $K = \alpha s^2$, where $s$ is the distance travelled by the particle. Determine the dimensions of $\alpha$.
A.
$[M^1 L^2 T^{-2}]$
B.
$[M^1 L^1 T^{-2}]$
C.
$[M^0 L^1 T^{-2}]$
D.
$[M^1 L^0 T^{-2}]$
Q10 DPT Dimensions Analysis MCQ
21 Jul 2026
Concept: Dimensional Analysis and Principle of Homogeneity of Dimensions.
If the centripetal force $F$ acting on a particle depends on its mass $M$, velocity $v$, and radius $r$ as $F = \frac{M v^n}{r}$, find the value of the exponent $n$ using dimensional analysis.
A.
1
B.
2
C.
3
D.
4
Q11 DPT Dimensions Analysis MCQ
21 Jul 2026
Concept: Dimensional Analysis and Principle of Homogeneity of Dimensions.
If the formula for the orbital velocity of a satellite is given by $v = \sqrt{\frac{G M}{r^n}}$ where $v$ is orbital velocity, $G$ is the universal gravitational constant, $M$ is the mass of the Earth, and $r$ is the radius of the orbit, find the value of the exponent $n$ for the formula to be dimensionally correct.
A.
1
B.
2
C.
3
D.
0
Q12 DPT Dimensions Analysis MCQ
21 Jul 2026
Concept: Dimensional Analysis and Principle of Homogeneity of Dimensions.
If the kinetic energy $KE$ of a body depends on the applied force $F$, velocity $v$, and time $t$ according to the relation $KE = F v^n t$, find the value of the variable exponent $n$ using dimensional analysis.
A.
0
B.
1
C.
2
D.
3