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JEE • PHYSICS • UNITS & MEASUREMENTS

Units & measurements practice · Medium

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These sets use single-correct-answer MCQs. They do not cover every JEE Main or JEE Advanced question format and are not full-length mock papers.

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Showing 151-180 of 502 questions

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151 Medium
151 of 502
Understanding +4 | -1
When two quantities are divided, the relative error in the
result is given by
View answer and explanation
Correct option: D
the sum of the relative error in the individual
quantities
Option D (the sum of the relative error in the individual quantities) is correct because relative errors add when quantities are divided.
152 Medium
152 of 502
Application +4 | -1
A physical quantity QQ is found to depend on observables x,yx, y, and zz, obeying relation Q=x3y2/zQ=x^3 y^2 / z. The percentage error in the measurements of x,yx, y, and zz are 1%,2%1 \%, 2 \% and 4%4 \% respectively. What is percentage error in the quantity QQ?
View answer and explanation
Correct option: C
11%11 \%
Option C (11%11 \%) is correct because the percentage error in Q is calculated by summing the percentage errors in x, y, and z, each multiplied by their respective exponents in the relation Q = x³y²/z.
153 Medium
153 of 502
Analyzing +4 | -1
The dimensions of (a⋅b)(a \cdot b) in the equation P=a−t2bxP=\frac{a-t^2}{b x} where PP is power, xx is distance and tt is time, are
View answer and explanation
Correct option: B
[M−1L−3T7]\left[{M}^{-1} {L}^{-3} {T}^7\right]
Option B is correct because the dimensions of a are [T²], and using the power equation, we can find the dimensions of b, and then calculate the dimensions of (a * b).
154 Medium
154 of 502
Remembering +4 | -1
The unit of absolute permittivity is
View answer and explanation
Correct option: B
Farad / meter
Option B (Farad / meter) is correct because absolute permittivity (ϵ0\epsilon_0) relates capacitance to physical dimensions, and its unit is Farad per meter.
155 Medium
155 of 502
Application +4 | -1
The heat generated in a circuit depends on resistance (R), current (I) and time of flow (t). If maximum errors in the above are 1%, 0.5%, 1% respectively error in measurement of power is (P=i2RP = {i^2}R)
View answer and explanation
Correct option: A
0.02
Option A (2%) is correct because the percentage error in power is calculated by summing the percentage errors in current (multiplied by 2) and resistance.
156 Medium
156 of 502
Understanding +4 | -1
The unit of viscosity in the CGS system is poise (P) and that in SI\mathrm{SI} is poiseuille (Pl). Which of the following statement is correct?
View answer and explanation
Correct option: C
10 P=1 Pl10 \mathrm{~P}=1 \mathrm{~P}{l}
Option C (10 P=1 Pl10 \mathrm{~P}=1 \mathrm{~P}{l}) is correct because 1 Poiseuille is equal to 10 Poise.
157 Medium
157 of 502
Remembering +4 | -1
Light Year is a unit of
View answer and explanation
Correct option: C
Distance
Option C (Distance) is correct because a light-year is defined as the distance light travels in one year.
158 Medium
158 of 502
Remembering +4 | -1
What is the SI unit of electron mobility?
View answer and explanation
Correct option: A
m2V−1s−1\mathrm{m}^2 \mathrm{V}^{-1} \mathrm{s}^{-1}
Option A (m2V−1s−1\mathrm{m}^2 \mathrm{V}^{-1} \mathrm{s}^{-1}) is the correct SI unit for electron mobility, derived from the relationship between drift velocity and electric field.
159 Medium
159 of 502
Analyzing +4 | -1
Of the following quantities, which one has dimensions
different from the remaining three?
View answer and explanation
Correct option: D
Angular momentum
Option D (Angular momentum) is correct because its dimensional formula [ML²T⁻¹] is different from the other three, which have [ML⁻¹T⁻²].
160 Medium
160 of 502
Application +4 | -1
E2μ0\frac{{E}^2}{\mu_0} has the dimensions (E={E}= electric field, μ0=\mu_0= permeability of free space)
View answer and explanation
Correct option: B
[MLT−4]\left[{MLT}^{-4}\right]
Option B ([MLT−4{MLT}^{-4}]) is correct because it represents the dimensions of energy density divided by the square of speed of light.
161 Medium
161 of 502
Understanding +4 | -1
The number of significant figures in the numbers 4.8000×1044.8000 \times {10^4} and 48000.50 are respectively
View answer and explanation
Correct option: B
5 and 7
Option B (5 and 7) is correct because significant figures include all certain digits plus one uncertain digit, and trailing zeros after the decimal point are significant.
162 Medium
162 of 502
Understanding +4 | -1
Assertion : Force cannot be added to pressure.

Reason : Because their dimensions are different.
View answer and explanation
Correct option: A
If both assertion and reason are true and the reason is the correct explanation of the assertion.
Option A (If both assertion and reason are true and the reason is the correct explanation of the assertion) is correct because force and pressure have different dimensions, preventing their direct addition.
163 Medium
163 of 502
Remembering +4 | -1
The unit of permittivity of free space ε0{\varepsilon _0} is
View answer and explanation
Correct option: D
Coulomb2/newton−metre2Coulom{b^2}/newton - metr{e^2}
Option D (Coulomb2/newton−metre2Coulom{b^2}/newton - metr{e^2}) is correct because it is derived from Coulomb's law, where permittivity is inversely proportional to force and directly proportional to the square of the charge and inversely proportional to the square of the distance.
164 Medium
164 of 502
Analyzing +4 | -1
Statement I: The distance covered by a body is given by s=u+12ats=u+\frac{1}{2} \frac{a}{t}, where the symbols have usual meaning.

Statement II: We can add, substract or equate quantities which have same dimensions.
View answer and explanation
Correct option: D
Statement I is false; Statement II is true
Option D is correct because Statement I is false, and Statement II is true. The given equation for distance is dimensionally incorrect, while it is true that quantities with the same dimensions can be added, subtracted, or equated.
165 Medium
165 of 502
Analyzing +4 | -1
Which pair do not have equal dimensions?
View answer and explanation
Correct option: B
Force and impulse
The correct answer is Force and impulse because they have different dimensions: Force is [MLT-2] and Impulse is [MLT-1].
166 Medium
166 of 502
Remembering +4 | -1
The wrong unit conversion among the following is
View answer and explanation
Correct option: D
1 astronomical unit =1.496×10−11 m=1.496 \times 10^{-11} \mathrm{~m}
Option D (1 astronomical unit =1.496×10−11 m=1.496 \times 10^{-11} \mathrm{~m}) is incorrect because the correct value is 1.496×1011 m1.496 \times 10^{11} \mathrm{~m}.
167 Medium
167 of 502
Remembering +4 | -1
Unit of electric flux is
View answer and explanation
Correct option: A
Vm
Option A (Vm) is correct because the unit of electric flux is Volt-meter, derived from the product of electric field and area.
168 Medium
168 of 502
Understanding +4 | -1
A length is measured as 2500 m2500 \mathrm{~m} by a meter scale. Which of the following statement is correct:
View answer and explanation
Correct option: C
Number of significant figure in given data is 4 but it should be written as 2.500×103 m2.500 \times 10^3 \mathrm{~m}
Option C (Number of significant figure in given data is 4 but it should be written as 2.500×103m2.500 \times 10^3 \mathrm{{m}}) is correct because trailing zeros are significant when a decimal point is present or implied, and scientific notation clarifies the significant figures.
169 Medium
169 of 502
Remembering +4 | -1
What is the SI unit of surface tension?
View answer and explanation
Correct option: A
Nm−1{Nm}^{-1}
Option A (Nm−1{Nm}^{-1}) is correct because surface tension is defined as force per unit length.
170 Medium
170 of 502
Application +4 | -1
If velocity (v), time (T) and mass (M) are taken as fundamental quantities, then dimensional formula for gravitational potential would be.
View answer and explanation
Correct option: C
[M0v2T0]\left[ {{M^0}{v^2}{T^0}} \right]
Option C ([M0v2T0][{M^0}{v^2}{T^0}]) is correct because gravitational potential is energy per unit mass, which has dimensions of velocity squared when velocity and mass are fundamental.
171 Medium
171 of 502
Application +4 | -1
If muscle times speed equals power, what is the ratio of the SI units and the CGS unit of muscle?
View answer and explanation
Correct option: A
10510^5
Option A (10510^5) is correct because the ratio of SI to CGS units of muscle (which is force) is 10510^5.
172 Medium
172 of 502
Remembering +4 | -1
If μ0\mu_0 and ε0\varepsilon_0 are the permeability and permittivity of free space, respectively, then the dimension of (1μ0ε0)\left(\frac{1}{\mu_0 \varepsilon_0}\right) is:
View answer and explanation
Correct option: B
L2/T2\mathrm{L}^2 / \mathrm{T}^2
Option B (L2/T2\mathrm{L}^2 / \mathrm{T}^2) is correct because 1μ0ε0\frac{1}{\mu_0 \varepsilon_0} represents the square of the speed of light, which has dimensions of length squared divided by time squared.
173 Medium
173 of 502
Understanding +4 | -1
Which of the following sets cannot enter into the list of fundamental quantities in any system of units?
View answer and explanation
Correct option: B
length, time, velocity
Option B (length, time, velocity) is the correct answer because velocity can be expressed in terms of length and time, making it a derived quantity, not a fundamental one.
174 Medium
174 of 502
Analyzing +4 | -1
Which one of the following does not have the same dimensions
View answer and explanation
Correct option: D
Planck constant and energy
Option D is correct. Planck's constant and energy have different dimensions. Planck's constant has dimensions of [ML²T⁻¹], while energy has dimensions of [ML²T⁻²].
175 Medium
175 of 502
Application +4 | -1
Error in the measurement of radius of a sphere is 1%. Then
error in the measurement of volume is
View answer and explanation
Correct option: C
0.03
Option C (3%) is correct because the percentage error in volume is three times the percentage error in radius, according to the formula for the volume of a sphere.
176 Medium
176 of 502
Understanding +4 | -1
Which one of the following represents the correct dimensions of the coefficient of viscosity?
View answer and explanation
Correct option: C
[ML−1T−1]\left[ {\mathrm{M}{\mathrm{L}^{ - 1}}{\mathrm{T}^{ - 1}}} \right]
Option C [ML−1T−1]\left[ {\mathrm{M}{\mathrm{L}^{ - 1}}{\mathrm{T}^{ - 1}}} \right] is correct because it represents the correct dimensional formula for the coefficient of viscosity derived from Newton's formula.
177 Medium
177 of 502
Understanding +4 | -1
Dimensional equation cannot be used
View answer and explanation
Correct option: C
To find out constant of proportionality which
may be a pure number
Option C (To find out constant of proportionality which may be a pure number) is correct because dimensional analysis cannot determine dimensionless constants in physical equations.
178 Medium
178 of 502
Analyzing +4 | -1
The relation tan⁡θ=v2/rg\tan \theta=v^2 / r g gives the angle of banking of the cyclist going round the curve. Here vv is the speed of the cyclist, rr is the radius of the curve, and gg is the acceleration due to gravity. Which of the following statements about the relation is true?
View answer and explanation
Correct option: A
It is both dimensionally as well as numerically correct.
Option A (It is both dimensionally as well as numerically correct) is correct because the expression tan⁡θ=v2/rg\tan \theta = v^2 / rg is dimensionally consistent and matches the standard formula for the angle of banking.
179 Medium
179 of 502
Analyzing +4 | -1
A rectangular beam which is supported at its two ends and leaded in the middle with weight w sags by an amount δ such that δ=wl34Yd3,  \delta = \frac{{w{l^3}}}{{4Y{d^3}}},\;, where l,dl,d and Y represent length, depth and elasticity respectively. Guess the unknown factor using dimensional considerations
View answer and explanation
Correct option: A
Breadth
The correct answer is A (Breadth) because dimensional analysis shows the unknown factor must have dimensions of length, which corresponds to breadth.
180 Medium
180 of 502
Understanding +4 | -1
[ML2T−2]\left[ {\mathrm{M}{\mathrm{L}^2}{\mathrm{T}^{ - 2}}} \right] are dimensions of
View answer and explanation
Correct option: B
Moment of force
Option B (Moment of force) is correct because the dimensions of moment of force (torque) are [ML2T−2]\left[ {\mathrm{M}{\mathrm{L}^2}{\mathrm{T}^{ - 2}}} \right].
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