Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
JEE Advanced 2023Paper 2
Exam
JEE Advanced
Year
2023
Paper
Paper 2
Subject
Physics
Chapter
Units and Dimensions

JEE Advanced 2023 · Paper 2 · Physics · Units and Dimensions

Young’s modulus of elasticity Y is expressed in terms of...

Young’s modulus of elasticity YY is expressed in terms of three derived quantities, namely, the gravitational constant GG, Planck’s constant hh and the speed of light cc, as Y=cαhβGγY = {c}^{\alpha}{h}^{\beta}{G}^{\gamma}. Which of the following is the correct option?

Options

  1. Aα=7,β=−1,γ=–2\alpha = 7, \beta = - 1, \gamma = – 2
  2. Bα=–7,β=–1,γ=–2\alpha = – 7, \beta = – 1, \gamma = – 2
  3. Cα=7,β=–1,γ=2\alpha = 7, \beta = – 1, \gamma = 2
  4. Dα=–7,β=1,γ=–2\alpha = – 7, \beta = 1, \gamma = – 2

Correct answer

A. α=7,β=−1,γ=–2\alpha = 7, \beta = - 1, \gamma = – 2

Step-by-step solution

Dimensions of Young's modulus: [M1L–1T–2]\left[{M}^{1}{L}^{– 1}T{}^{– 2}\right]

Dimensions of velocity of light: \left[{M}^{0}{L}^{1}{T}^{– 1}\right]</p><p>DimensionsofPlanck′sconstant:[M1L2T–1]</p><p>Dimensions of Planck's constant: \left[{M}^{1}{L}^{2}{T}^{– 1}\right]

Dimensions of Gravitational constant: \left[{M}^{– 1}{L}^{3}{T}^{– 2}\right]</p><p>Now,asgiveninthequestion</p><p>Now, as given in the question

Y=cαhβGγY = {c}^{\alpha}{h}^{\beta}{G}^{\gamma}

⇒[M1L–1T–2]⇒ \left[{M}^{1}{L}^{– 1}T{}^{– 2}\right] = {\left[{M}^{0}{L}^{1}{T}^{– 1}\right]}^{\alpha}{\left[{M}^{1}{L}^{2}{T}^{– 1}\right]}^{\beta}{\left[{M}^{– 1}{L}^{3}{T}^{– 2}\right]}^{\gamma}

Comparing exponent of the M, L & T both sides, we get</p><p></p><p>1 = \beta - \gamma ⇒ \beta = 1 + \gamma . . . \left(1\right)</p><p></p><p>- 1 = \alpha + 2\beta + 3\gamma . . . \left(2\right)

and −2=−α−β−2γ...(3)- 2 = - \alpha - \beta - 2\gamma . . .\left(3\right)

From equation(1) and (2), we get</p><p></p><p>- 1 = \alpha + 2\left(1 + \gamma\right) + 3\gamma ⇒ \alpha + 5\gamma = - 3 . . . \left(4\right)

From equation(1)and(3),weget</p><p>and (3), we get</p><p>- 2 = - \alpha - \left(1 + \gamma\right) - 2\gamma ⇒ \alpha + 3\gamma = 1 . . . \left(5\right)

From equation(4)andequation(5),weget</p><p>and equation(5), we get</p><p>\alpha = 7, \gamma = – 2andthenand then\beta = 1 + \gamma = - 1.

Practice Units and Dimensions on Quantrex Academy →

More from Units and Dimensions

In a new system of units, the units of mass, length, time and current are 5 kg, 5 m, 5 s… JEE Advanced 2026A new unit (α) of length is chosen such that it is equal to the speed of light in vacuum.… JEE Main 2026Consider the equation H = (x^p ε^q E^r)/(t^s) , where H= magnetic field; E= electric… JEE Main 2026The percentage error in the calculated volume of a sphere, if there is 2\% error in its… JEE Main 2026Match List - I with List - II. List - I List - II A. Boltzmann constant I. [M^ -1 L^3T^… JEE Main 2026The potential energy of a particle changes with distance x from a fixed origin as V = A x… JEE Main 2026Match List-I with List-II. List-I List-II A. Meter (L) I. (hc)/(G) B. Second (S) II.… JEE Main 2026L , C and R represents physical quantities inductance, capacitance and resistance… JEE Main 2026 Full Units and Dimensions list All JEE Advanced PYQs