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NEET • PHYSICS • UNITS & MEASUREMENTS

Units & measurements practice · Hard

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Showing 1-30 of 41 questions
1 Hard
1 of 41
Analyzing +4 | -1
Pressure gradient has the same dimension as that of
View answer and explanation
Correct option: D
None of these
Option D (None of these) is correct because pressure gradient has dimensions of [ML⁻²T⁻²], velocity gradient has dimensions of [T⁻¹], and potential gradient has dimensions of [MLT⁻³A⁻¹], and energy gradient has dimensions of [ML²T⁻²L⁻¹] = [MLT⁻²], so none match.
2 Hard
2 of 41
Application +4 | -1
If the time period (T) of vibration of a liquid drop depends on surface tension (S), radius (r) of the drop and density (ρ\rho) of the liquid, then the expression of T is
View answer and explanation
Correct option: A
T=kρr3/ST = k\sqrt {\rho {r^3}/S}
Option A (T=kρr3/ST = k\sqrt {\rho {r^3}/S}) is correct because dimensional analysis confirms that the dimensions of this expression match the dimensions of time.
3 Hard
3 of 41
Application +4 | -1
The length of a simple pendulum is about 100 cm known to an accuracy of 1 mm. Its period of oscillation is 2s determined by measuring the time for 100 oscillations using a clock of 0.1 s resolution. What is the accuracy in the determined value of g?
View answer and explanation
Correct option: A
0.2 %0.2\,\%
Option A (0.2 %0.2\,\%) is correct because it accurately reflects the percentage error in 'g' based on the given uncertainties in length and time period.
4 Hard
4 of 41
Application +4 | -1
The potential energy of a particle varies with distance x from a fixed origin as U=(AXx+B);U = \left( {\frac{{A\sqrt X }}{{x + B}}} \right);; where A and B are constants. The dimensions of AB are
View answer and explanation
Correct option: D
[ML7/2T−2]\left[ {\mathrm{M}{\mathrm{L}^{7/2}}{\mathrm{T}^{ - 2}}} \right]
Option D ([ML7/2T−2][{\mathrm{M}{\mathrm{L}^{7/2}}{\mathrm{T}^{ - 2}}}]) is correct because it correctly calculates the dimensions of AB based on the given potential energy equation.
5 Hard
5 of 41
Remembering +4 | -1
To determine refractive index of glass also using
a travelling microscope, minimum number of
readings required are
View answer and explanation
Correct option: C
Three
Option C (Three) is correct because a minimum of three readings are required to determine the refractive index of glass using a travelling microscope.
6 Hard
6 of 41
Application +4 | -1
A body travels uniformly a distance of (20.0±0.2) m(20.0 \pm 0.2)\,m in time (4.0±0.04) s(4.0 \pm 0.04)\,s. The velocity of the body is
View answer and explanation
Correct option: D
(5.0±0.1) ms−1(5.0 \pm 0.1)\,m{s^{ - 1}}
Option D ((5.0±0.1) ms−1(5.0 \pm 0.1)\,m{s^{ - 1}}) is correct because it accurately calculates the velocity and its associated uncertainty using the given distance and time with their respective uncertainties.
7 Hard
7 of 41
Application +4 | -1
The vernier scale of a callipers is divided into 20 divisions which coincide with 18 main scale divisions. Each main scale division is 0.2 mm. The least count of the instrument is
View answer and explanation
Correct option: B
0.02 mm
Option B (0.02 mm) is correct because the least count is calculated by finding the difference between one main scale division and one vernier scale division.
8 Hard
8 of 41
Application +4 | -1
If x=A2B3CDx = \frac{{{A^2}{B^3}}}{{C\sqrt D }} and percentage errors in A, B, C & D are 1%, 2%, 3% and 4% respectively, the percentage error in xx is
View answer and explanation
Correct option: D
0.13
Option D (0.13) is correct because it accurately calculates the percentage error in x using the given percentage errors in A, B, C, and D.
9 Hard
9 of 41
Analyzing +4 | -1
The mass of the liquid flowing per second per unit area of cross-section of the tube is proportional to (pressure difference across the ends) n^n and (average velocity m^m of the liquid. Which one of the following relation is correct?
View answer and explanation
Correct option: B
m=−nm=-n
Option B (m=−nm=-n) is correct because the mass flow rate per unit area is proportional to (pressure difference)n^n and (average velocity)m^m, and based on dimensional analysis, m and n must have opposite signs and equal magnitudes.
10 Hard
10 of 41
Application +4 | -1
If force (F) , length (L) and time (T) are assumed to be fundamental units, then the dimensional formula of the mass will be
View answer and explanation
Correct option: A
FL−1T2F{L^{ - 1}}{T^2}
Option A (FL−1T2F{L^{ - 1}}{T^2}) is correct because it represents the dimensional formula of mass when force, length, and time are fundamental units.
11 Hard
11 of 41
Analyzing +4 | -1
Velocity of sound in a medium is given by A1/2 d−1/2{A^{1/2}}\,{d^{ - 1/2}} where dd is density of medium. Then AA represents
View answer and explanation
Correct option: A
Elastic constant
Option A (Elastic constant) is correct because dimensional analysis shows that A has the dimensions of an elastic constant (e.g., Young's modulus).
12 Hard
12 of 41
Application +4 | -1
The expression for centripetal force depends upon mass of body, speed of the body and the radius of circular path. Find the expression for centripetal force
View answer and explanation
Correct option: B
F=mv2rF = \frac{{m{v^2}}}{r}
Option B (F=mv2rF = \frac{{m{v^2}}}{r}) is correct because it represents the standard formula for centripetal force.
13 Hard
13 of 41
Application +4 | -1
A resistor of 4 kΩ with tolerance 10% is connected in parallel with a resistor of 6 kW with tolerance 100%. The tolerance of the parallel combination is nearly
View answer and explanation
Correct option: C
0.3
Option C (0.3) is correct because the tolerance of the parallel combination is calculated by considering the individual tolerances and resistances.
14 Hard
14 of 41
Application +4 | -1
If L1=(2.02±0.01) m{L_1} = (2.02 \pm 0.01)\,m and L2=(1.02±0.01) m{L_2} = (1.02 \pm 0.01)\,m then L1+2L2{L_1} + 2{L_2} is (in m)
View answer and explanation
Correct option: B
4.06±0.034.06 \pm 0.03
Option B (4.06±0.034.06 \pm 0.03) is correct because it accurately calculates the sum and its associated error.
15 Hard
15 of 41
Application +4 | -1
If pressure P, velocity V and time T are taken as fundamental physical quantities, the dimensional formulae of the force is
View answer and explanation
Correct option: A
PV2T2P{V^2}{T^2}
Option A (PV2T2P{V^2}{T^2}) is correct because it yields the dimensions of force when pressure, velocity, and time are taken as fundamental quantities.
16 Hard
16 of 41
Application +4 | -1
If velocity v, acceleration A and force F are chosen a fundamental quantities, then the dimensional formula of angular momentum in terms of v,A and F would be
View answer and explanation
Correct option: B
Fv3A−2F{v^3}{A^{ - 2}}
Option B (Fv3A−2F{v^3}{A^{ - 2}}) is correct because it involves expressing the dimensions of angular momentum in terms of force (F), velocity (v), and acceleration (A). By equating the dimensions of angular momentum to the dimensions of the given expression, we can solve for the powers of F, v, and A.
17 Hard
17 of 41
Application +4 | -1
If F=6πηarbvcF = 6\mathrm{\pi }{\mathrm{\eta }^\mathrm{a}}{r^b}{v^c} Where F=viscous force
η\mathrm{\eta }= coefficient of viscosity
r= radius of spherical body
v= terminal velocity of the body.
Find the values of a,b and c.
View answer and explanation
Correct option: B
a=1,b=1,c=1a = 1,b = 1,c = 1
Option B (a = 1, b = 1, c = 1) is correct because dimensional analysis of the viscous force equation yields these values for the exponents.
18 Hard
18 of 41
Application +4 | -1
In finding out refractive index of glass slab the following observations were made through travelling microscope 50 vernier scale division = 49 MSD; 20 divisions on main scale in each cm\mathrm{cm}
For mark on paper
MSR=8.45 cm,VC=26\mathrm{MSR}=8.45 \mathrm{~cm}, \mathrm{VC}=26
For mark on paper seen through slab
MSR=7.12 cm,VC=41\mathrm{MSR}=7.12 \mathrm{~cm}, \mathrm{VC}=41
For powder particle on the top surface of the glass slab
MSR⁡=4.05 cm,VC=1\operatorname{MSR}=4.05 \mathrm{~cm}, \mathrm{VC}=1
(MSR=(\mathrm{MSR}= Main Scale Reading, VC=\mathrm{VC}= Vernier Coincidence)
Refractive index of the glass slab is:
View answer and explanation
Correct option: A
1.42
Option A (1.42) is correct because the refractive index is calculated by dividing the real depth by the apparent depth.
19 Hard
19 of 41
Application +4 | -1
In the relation p=αβ  e−αzkθ,  pp = \frac{\mathrm{\alpha }}{\mathrm{\beta }}\mathrm{\;}{\mathrm{e}^{ - \frac{{\alpha z}}{{k\mathrm{\theta }}}}},\mathrm{\;}p , is the pressure, z the distance, k is Boltzmann constant and θ\theta is the temperature, the dimensional formula of β\beta will be
View answer and explanation
Correct option: A
[M0L2T0]\left[ {{\mathrm{M}^0}{\mathrm{L}^2}{\mathrm{T}^0}} \right]
Option A ([M⁰L²T⁰]) is correct because the exponent in the exponential term must be dimensionless, allowing us to determine the dimensions of β.
20 Hard
20 of 41
Application +4 | -1
The period of oscillation of a simple pendulum in the experiment is recorded as 2.63 s, 2.56 s, 2.42 s, 2.71 s and 2.80 s respectively. The average absolute error is
View answer and explanation
Correct option: B
0.11 s
Option B (0.11 s) is correct because it represents the average of the absolute differences between each measurement and the mean value.
21 Hard
21 of 41
Application +4 | -1
Expression for time in terms of G (universal gravitational constant), h (Plank’s constant) and c (speed of light) is proportional to
View answer and explanation
Correct option: C
Ghc5\sqrt {\frac{{Gh}}{{{c^5}}}}
Option C (Ghc5\sqrt {\frac{{Gh}}{{{c^5}}}}) is correct because it correctly relates time to G, h, and c using dimensional analysis.
22 Hard
22 of 41
Analyzing +4 | -1
The liquid drop of density ρ,\rho , radius rr and surface tension σ\sigma oscillates with time period T. Which of the following expression for T2{T^2} is correct
View answer and explanation
Correct option: A
ρr3σ\frac{{\rho {r^3}}}{\sigma }
Option A (ρr3σ\frac{{\rho {r^3}}}{\sigma }) is correct because it gives the correct relationship between time period, density, radius, and surface tension based on dimensional analysis.
23 Hard
23 of 41
Application +4 | -1
The least count of the main scale of a vernier callipers is 1 mm. Its vernier scale is divided into 10th division and coincide with 9th division of the main scale. When jaws are touching each other, the 7th division of vernier scale coincides with a division of main scale and the zero of vernier scale is lying right side of the zero of main scale. When this vernier is used to measure length of a cylinder the zero of the vernier scale lies between 3.1 cm and 3.2 cm and 4th VSD coincides with a main scale division. The length of the cylinder is (VSD is vernier scale division)
View answer and explanation
Correct option: C
3.07 cm
Option C (3.07 cm) is correct because the length is calculated by adding the main scale reading and the vernier scale reading, then correcting for the zero error.
24 Hard
24 of 41
Analyzing +4 | -1
Three identical spheres of mass 'm', are placed at the vertices of an equilateral triangle of length 'a'. When released, they interact only through gravitational force and collide after a time T = 4 seconds. If the sides of the triangle are increased to length '2a' and also the masses of the spheres are made '2m', then they will collide after _____ seconds.
View answer and explanation
Correct option: A
8
Option A (8) is correct because the time of collision is proportional to the side length of the triangle when the masses are scaled proportionally.
25 Hard
25 of 41
Application +4 | -1
The velocity v of water waves may depend on their wavelength (λ\lambda), the density of water (ρ\rho) and the acceleration due to gravity (g). The method of dimensions gives the relation between these quantities as
View answer and explanation
Correct option: B
v2∝gλ{v^2} \propto \mathrm{g}\lambda
Option B (v2∝gλ{v^2} \propto \mathrm{g}\lambda) is correct because it correctly relates the velocity of water waves to gravity and wavelength using dimensional analysis.
26 Hard
26 of 41
Application +4 | -1
The value of two resistors are R1=(6±0.3)k Ω{R_1} = (6 \pm 0.3)k\,\Omega and R2=(10±0.2)k Ω.{R_2} = (10 \pm 0.2)k\,\Omega. The percentage error in the equivalent resistance when they are connected in parallel is
View answer and explanation
Correct option: C
0.10125
Option C (0.10125) is correct because it accurately calculates the percentage error in the equivalent resistance when the resistors are connected in parallel.
27 Hard
27 of 41
Application +4 | -1
The speed (v) of ripples on the surface of water depends on surface tension (σ\sigma), density (ρ\rho) and wavelength (λ\lambda). The square of speed (v) is proportional to
View answer and explanation
Correct option: A
σρλ\frac{\sigma }{{\rho \lambda }}
Option A (σρλ\frac{\sigma }{{\rho \lambda }}) is correct because it correctly relates the speed of ripples to surface tension, density, and wavelength using dimensional analysis.
28 Hard
28 of 41
Analyzing +4 | -1
Given a charge q,q, current II and permeability of vacuum μ0.\mu_0. Which of the following quantity has the dimension of momentum?
View answer and explanation
Correct option: B
qμ0Iq \mu_0 I
Option B (qμ0Iq \mu_0 I) is correct because its dimensional formula matches that of momentum.
29 Hard
29 of 41
Analyzing +4 | -1
In the determination of Young’s modulus (Y=4  MLgπ  ℓd2)\left( {Y = \frac{{4\;MLg}}{{\pi \;\ell {d^2}}}} \right) by using Searle’s method, a wire of length L=2m and diameter d=0.5mm is used. For a load M=2.5 kg, an extension ℓ=0.25mm\ell = 0.25mm in the length of the wire is observed. Quantities d and ℓ\ell are measured using a screw gauge and a micrometer, respectively. They have the same pitch of 0.5 mm. The number of divisions on their circular scale is 100. The contributions to the maximum probable scale is 100. The contributions to the maximum probable error of the Y measurement
View answer and explanation
Correct option: A
Due to the errors in the measurements of d and ℓ\ell are the same
Option A (Due to the errors in the measurements of d and ℓ\ell are the same) is correct because the least count is the same for both instruments, and their contributions to the error in Y are equally weighted.
30 Hard
30 of 41
Application +4 | -1
There are atomic clocks capable of measuring time with an accuracy of 1 part in 1011{10^{11}}. If two such clocks are operated with precision, then after running for 5000 years, these will record
View answer and explanation
Correct option: A
A difference of nearly 1 s
Option A (A difference of nearly 1 s) is correct because it involves calculating the time difference between two atomic clocks with an accuracy of 1 part in 1011{10^{11}} after running for 5000 years. The calculation involves converting years to seconds and then finding the maximum possible difference.
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  • ✓ This set contains 41 single-correct-answer MCQs on UNITS & MEASUREMENTS.
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