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Explore popular questions from Physical World and Measurement for NEET. This collection covers Physical World and Measurement previous year NEET questions hand picked by experienced teachers.

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Q 1. The density of material in CGS system of units is 4{tex} \mathrm { g } / \mathrm { cm } ^ { 3 } . {/tex} In a system of units in which unit of length is 10{tex} \mathrm { cm } {/tex} and unit of mass is 100{tex} \mathrm { g } {/tex} , the value of density of material will be

A

0.4 unit

40 unit

C

400 unit

D

0.04 unit

Explanation

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Q 2. The time period of a body under S.H.M. is represented by: {tex} \mathrm { T } = \mathrm { P } ^ { \mathrm { a } } \mathrm { D } ^ { \mathrm { b } } \mathrm { S } ^ { \mathrm { c } } {/tex} where {tex} \mathrm { P } {/tex} is pressure, {tex} \mathrm { D } {/tex} is density and {tex} \mathrm { S } {/tex} is surface tension, then values of {tex} \mathrm { a } , \mathrm { b } {/tex} and {tex} \mathrm { c } {/tex} are

{tex} - \frac { 3 } { 2 } , \frac { 1 } { 2 } , 1 {/tex}

B

{tex} - 1 , - 2,3 {/tex}

C

{tex} \frac { 1 } { 2 } , - \frac { 3 } { 2 } , - \frac { 1 } { 2 } {/tex}

D

{tex} 1,2 , \frac { 1 } { 3 } {/tex}

Explanation

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Q 3. The respective number of significant figures for the numbers {tex} 23.023,0.0003 {/tex} and {tex} 2.1 \times 10 ^ { - 3 } {/tex} are

{tex} 5,1,2 {/tex}

B

{tex} 5,1,5 {/tex}

C

{tex} 5,5,2 {/tex}

D

{tex} 4,4,2 {/tex}

Explanation

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Q 4. Young's modulus of a material has the same unit as that of

pressure

B

strain

C

compressibility

D

force

Explanation

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Q 5. Of the following quantities, which one has dimensions different from the remaining three?

A

Energy per unit volume

B

Force per unit area

C

Product of voltage and charge per unit volume

Angular momentum

Explanation

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Q 6. The pressure on a square plate is measured by measuring the force on the plate and length of the sides of the plate by using the formula {tex} P = \frac { F } { \ell ^ { 2 } } {/tex} . If the maximum errors in the measurement of force and length are 4{tex} \% {/tex} and 2{tex} \% {/tex} respectively, then the maximum error in the measurement of pressure is

A

1{tex} \% {/tex}

B

2{tex} \% {/tex}

8{tex} \% {/tex}

D

10{tex} \% {/tex}

Explanation

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Q 7. The siemen is the SI unit of

A

resistivity

B

resistance

C

conductivity

conductance

Explanation

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Q 8. An object is moving through the liquid. The viscous damping force acting on it is proportional to the velocity. Then dimensions of constant of proportionality are

A

{tex} \left[ \mathrm { ML } ^ { - 1 } \mathrm { T } ^ { - 1 } \right] {/tex}

B

{tex} \left[ \mathrm { MLT } ^ { - 1 } \right] {/tex}

C

{tex} \left[ \mathrm { M } ^ { 0 } \mathrm { L T} ^ { -1 } \right] {/tex}

{tex} \left[ \mathrm { ML } ^ { 0 } \mathrm { T } ^ { - 1 } \right] {/tex}

Explanation

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Q 9. The least count of a stop watch is 0.2 second. The time of 20 oscillations of a pendulum is measured to be 25 second. The percentage error in the measurement of time will be

A

8{tex} \% {/tex}

B

1.8{tex} \% {/tex}

0.8{tex} \% {/tex}

D

0.1{tex} \% {/tex}

Explanation

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Q 10. Weber is the unit of

A

magnetic susceptibility

B

intensity of magnetisation

magnetic flux

D

magnetic permeability

Explanation

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Q 11. The physical quantity which has the dimensional formula {tex} \left[ \mathrm { M } ^ { 1 } \mathrm { T } ^ { - 3 } \right] {/tex} is

A

surface tension

solar constant

C

density

D

compressibility

Explanation

Solar constant = energy/area/time = {tex} \frac {ML^{2}T^{-2}}{L^{2}T} {/tex} = [M1T-3]

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Q 12. The dimensions of Wien's constant are

A

{tex} \left[ \mathrm { ML } ^ { 0 } \mathrm { T } \mathrm { K } \right] {/tex}

{tex} \left[ \mathrm { M } ^ { 0 } \mathrm { LT } ^ { 0 } \mathrm { K } \right] {/tex}

C

{tex} \left[ \mathrm { M } ^ { 0 } \mathrm { L } ^ { 0 } \mathrm { T } \mathrm { K } \right] {/tex}

D

{tex} [ \mathrm { MLTK } ] {/tex}

Explanation

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Q 13. If the capacitance of a nanocapacitor is measured in terms of a unit {tex}'u'{/tex} made by combining the electric charge {tex}'e'{/tex}, Bohr radius {tex}'a_o'{/tex} , Planck's constant 'h' and speed Of light {tex}'c'{/tex} then

A

{tex} \mathrm { u } = \frac { \mathrm { e } ^ { 2 } \mathrm { h } } { \mathrm { a } _ { 0 } } {/tex}

B

{tex} \mathrm { u } = \frac { \mathrm { hc } } { \mathrm { e } ^ { 2 } \mathrm { a } _ { 0 } } {/tex}

C

{tex} \mathrm { u } = \frac { \mathrm { e } ^ { 2 } \mathrm { c } } { \mathrm { ha } _ { 0 } } {/tex}

{tex} \mathrm { u } = \frac { \mathrm { e } ^ { 2 } \mathrm { a } _ { 0 } } { \mathrm { hc } } {/tex}

Explanation

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Q 14. The dimensions of {tex} \frac { 1 } { \epsilon _ { \mathrm { o } } } \frac { \mathrm { e } ^ { 2 } } { \mathrm { hc } } {/tex} are

A

{tex} \mathrm { M } ^ { - 1 } \mathrm { L } ^ { - 3 } \mathrm { T } ^ { 4 } \mathrm { A } ^ { 2 } {/tex}

B

{tex} \mathrm { ML } ^ { 3 } \mathrm { T } ^ { - 4 } \mathrm { A } ^ { - 2 } {/tex}

{tex} \mathrm{{ M } ^ { 0 } { L } ^ { 0 } { T } ^ { 0 } { A } ^ { 0 }} {/tex}

D

{tex} \mathrm { M } ^ { - 1 } \mathrm { L } ^ { - 3 } \mathrm { T } ^ { 2 } \mathrm { A } {/tex}

Explanation

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Q 15. The density of a cube is measured by measuring its mass and length of its sides. If the maximum error in the measurement of mass and length are 4{tex} \% {/tex} and 3{tex} \% {/tex} respectively, the maximum error in the measurement of density will be

A

7{tex} \% {/tex}

B

9{tex} \% {/tex}

C

12{tex} \% {/tex}

13{tex} \% {/tex}

Explanation

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Q 16. If velocity {tex} ( \mathrm { V } ) , {/tex} force {tex} ( \mathrm { F } ) {/tex} and energy {tex} ( \mathrm { E } ) {/tex} are taken as fundamental units, then dimensional formula for mass will be

A

{tex} \mathrm { V } ^ { - 2 } \mathrm { F } ^ { 2 } \mathrm { E } {/tex}

B

{tex} \mathrm{V^0FE^2}{/tex}

C

{tex} \mathrm { VF } ^ { - 2 } \mathrm { E } ^ { 0 } {/tex}

{tex} \mathrm { V } ^ { - 2 } \mathrm { F } ^ { 0 } \mathrm { E } {/tex}

Explanation


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Q 17. Multiply 107.88 by 0.610 and express the result with correct number of significant figures.

A

65.8068

B

65.807

C

65.81

65.8

Explanation

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Q 18. Which of the following is a dimensional constant?

A

Refractive index

B

Poissons ratio

C

Strain

Gravitational constant

Explanation

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Q 19. If {tex} \mathrm { E } , \mathrm { m } , \mathrm { J } {/tex} and {tex} \mathrm { G } {/tex} represent energy, mass, angular momentum and gravitational constant respectively, then the dimensional formula of {tex} \mathrm { E } \mathrm { J } ^ { 2 } / \mathrm { m } ^ { 5 } \mathrm { G } ^ { 2 } {/tex} is same as that of the

angle

B

length

C

mass

D

time

Explanation

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Q 20. The refractive index of water measured by the relation {tex} \mathrm { m } = \frac { \text { real depth } } { \text { apparent depth } } {/tex} is found to have values of {tex} 1.34, 1.38, 1.32 {/tex} and {tex} 1.36 ; {/tex} the mean value of refractive index with percentage error is

{tex} 1.35 \pm 1.48 \% {/tex}

B

{tex} 1.35 \pm 0 \% {/tex}

C

{tex} 1.36 \pm 6 \% {/tex}

D

{tex} 1.36 \pm 0 \% {/tex}

Explanation

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Q 21. If e is the charge, {tex} \mathrm V {/tex} the potential difference, {tex} \mathrm T {/tex} the temperature, then the units of {tex} \frac { \mathrm { eV } } { \mathrm { T } } {/tex} are the same as that of

A

Planck's constant

B

Stefan's constant

Boltzmann's constant

D

gravitational constant

Explanation

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Q 22. The dimensions of mobility are

A

{tex} \mathrm { M } ^ { - 2 } \mathrm { T } ^ { 2 } \mathrm { A } {/tex}

{tex} \mathrm { M } ^ { - 1 } \mathrm { T } ^ { 2 } \mathrm{ A } {/tex}

C

{tex} \mathrm { M } ^ { - 2 } \mathrm { T } ^ { 3 } \mathrm { A } {/tex}

D

{tex} \mathrm { M } ^ { - 1 } \mathrm { T } ^ { 3 } \mathrm { A } {/tex}

Explanation

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Q 23. Two quantities {tex} A {/tex} and {tex} B {/tex} have different dimensions which mathematical operation given below is physically meaningful?

{tex} { A } / { B } {/tex}

B

{tex} A + B {/tex}

C

{tex} A - B {/tex}

D

{tex} A = B {/tex}

Explanation

As per the principle of homogeneity of dimension, addition subtraction or equality between two quantities of different dimensions are not possible while division and multiplication are possible. Hence option A is corerct.

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Q 24. The velocity of water waves (v) may depend on their wavelength 1 , the density of water {tex} r {/tex} and the acceleration due to gravity, g. The method of dimensions gives the relation between these quantities is

A

v

{tex} v ^ { 2 } \propto g \lambda {/tex}

C

{tex} v ^ { 2 } \propto g \lambda ^ { 2 } {/tex}

D

{tex} v ^ { 2 } \propto g ^ { - 1 } \lambda ^ { 2 } {/tex}

Explanation

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Q 25. The physical quantities not having same dimensions are

A

torque and work

momentum and Planck's constant

C

stress and Young's modulus

D

speed and {tex} \left( m _ { 0 } e _ { 0 } \right) ^ { - 1 / 2 } {/tex}

Explanation