Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
JEE Main 20205 SeptemberEvening Shift
Exam
JEE Main
Year
2020
Date
5 September
Shift
Evening Shift
Subject
Physics
Chapter
Units and Dimensions

JEE Main 2020 · 5 September · Evening Shift · Physics · Units and Dimensions

The quantities x = 1 μ _ 0 ∈ _ 0 , y = (E)/(B) and z = (l)/(CR) are...

The quantities x=1μ0∈0,y=EBx = \dfrac{1}{\sqrt{{\mu}_{0}{\in}_{0}}}, y = \dfrac{E}{B} and z=lCRz = \dfrac{l}{CR} are defined where C-capacitance, R-Resistance, ℓ−ℓ -length, E-Electric field, B-magnetic field and ∈0,μ0,−\in 0, \mu0, -free space permittivity and permeability respectively. Then:

Options

  1. Ax, y and z have the same dimension.
  2. BOnly x and z have the same dimension
  3. COnly x and y have the same dimension
  4. DOnly y and z have the same dimension.

Correct answer

A. x, y and z have the same dimension.

Step-by-step solution

(a) Dimensions of quantity are given bellow

μ0=[TmA−1]=[Wbm−1A−1]=[Vsm−1C−1s]=[NC−2s2]ε0=[C2N−1m−2]{\mu}_{0} = \left[Tm{A}^{- 1}\right] = \left[Wb{m}^{- 1}{A}^{- 1}\right] = \left[Vs{m}^{- 1}{C}^{- 1}s\right] = \left[N{C}^{- 2}{s}^{2}\right]{ε}_{0} = \left[{C}^{2}{N}^{- 1}{m}^{- 2}\right]

Now the dimension of xx is given by

\left[x\right] = \dfrac{1}{\left[\sqrt{{\mu}_{0}{\in}_{0}}\right]} = \sqrt{\dfrac{1}{\left[N{C}^{- 2}{s}^{2}\right]\left[{C}^{2}{N}^{- 1}{m}^{- 2}\right]}}\left[x\right] = m{s}^{- 1}</p><p>(b)Thedimensionofelectricandmagneticfieldisgivenby,</p><p></p><p>(b) The dimension of electric and magnetic field is given by,</p><p>B = \left[T\right] = \left[Wb{m}^{- 2}\right] = \left[Vs{m}^{- 2}\right]E = \left[V{m}^{- 1}\right]</p><p>Nowthedimensionof</p><p>Now the dimension ofyisgivenby,</p><p>[y]=[E][B]=[Vm−1][Vsm−2]=ms−1is given by,</p><p> \left[y\right] = \dfrac{\left[E\right]}{\left[B\right]} = \dfrac{\left[V{m}^{- 1}\right]}{\left[Vs{m}^{- 2}\right]} = m{s}^{- 1}

(c) The dimension of capacitance and resistance is given by,

C=[CV−1]R=[VC−1s]C = \left[C{V}^{- 1}\right]R = \left[V{C}^{- 1}s\right]

Now the dimension of zz is given by

\left[z\right] = \dfrac{\left[l\right]}{\left[CR\right]} = \dfrac{\left[m\right]}{\left[C{V}^{- 1}\right]\left[V{C}^{- 1}s\right]} = m{s}^{- 1}

All quantities are having the dimensions of velocity.

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 Main PYQs