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If electric charge e, electron's mass m,...

If electric charge e, electron's mass m, speed of light in vaccum c and Planck's constant h are taken as fundamental quantities, the permeability of vaccum `mu_(0)` can be expressed in units of :

A

`((hc)/(me^2))`

B

`((h)/(me^2))`

C

`((h)/(ce^2))`

D

`((mc^2)/(he^2))`

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The correct Answer is:
To express the permeability of vacuum \( \mu_0 \) in terms of the fundamental quantities: electric charge \( e \), electron's mass \( m \), speed of light in vacuum \( c \), and Planck's constant \( h \), we can use dimensional analysis. Let's go through the steps systematically. ### Step 1: Identify the dimensions of the quantities involved 1. **Electric Charge \( e \)**: The dimension of electric charge is given by \( [e] = [I][T] \) (where \( I \) is current and \( T \) is time). 2. **Mass \( m \)**: The dimension of mass is \( [m] = [M] \). 3. **Speed of Light \( c \)**: The dimension of speed is \( [c] = [L][T]^{-1} \). 4. **Planck's Constant \( h \)**: The dimension of Planck's constant is \( [h] = [M][L]^2[T]^{-1} \). ### Step 2: Write the dimension of permeability of vacuum \( \mu_0 \) The dimension of permeability of vacuum is given by: \[ [\mu_0] = [M][L][T]^{-2}[A]^{-2} \] where \( [A] \) is the dimension of electric current. ### Step 3: Express \( \mu_0 \) in terms of the fundamental quantities We want to express \( \mu_0 \) in the form: \[ \mu_0 = e^x m^y c^z h^w \] where \( x, y, z, w \) are the powers we need to determine. ### Step 4: Set up the equations based on dimensions From the dimensions, we have: \[ [M][L][T]^{-2}[A]^{-2} = [I]^x [M]^y [L]^z [T]^{-2z} [M]^w [L]^{2w} [T]^{-w} \] ### Step 5: Equate the dimensions Now we can equate the powers of each dimension: 1. For \( M \): \[ 1 = y + w \] 2. For \( L \): \[ 1 = z + 2w \] 3. For \( T \): \[ -2 = -2z - w \] 4. For \( A \): \[ -2 = x \] ### Step 6: Solve the equations From the equation for \( A \): \[ x = -2 \] Substituting \( x = -2 \) into the equation for \( T \): \[ -2 = -2z - w \implies w = -2 - 2z \] Now substituting \( w \) into the equation for \( M \): \[ 1 = y + (-2 - 2z) \implies y = 3 + 2z \] Substituting \( w \) into the equation for \( L \): \[ 1 = z + 2(-2 - 2z) \implies 1 = z - 4 - 4z \implies 5z = 5 \implies z = 1 \] Now substituting \( z = 1 \) back to find \( w \): \[ w = -2 - 2(1) = -4 \] Now substituting \( z = 1 \) into \( y \): \[ y = 3 + 2(1) = 5 \] ### Step 7: Write the final expression for \( \mu_0 \) Now we have: - \( x = -2 \) - \( y = 5 \) - \( z = 1 \) - \( w = -4 \) Thus, we can express \( \mu_0 \) as: \[ \mu_0 = e^{-2} m^{5} c^{1} h^{-4} \] ### Conclusion Rearranging gives us: \[ \mu_0 = \frac{h}{e^2 c} \] ### Final Answer The permeability of vacuum \( \mu_0 \) can be expressed in units of: \[ \mu_0 = \frac{h}{e^2 c} \]

To express the permeability of vacuum \( \mu_0 \) in terms of the fundamental quantities: electric charge \( e \), electron's mass \( m \), speed of light in vacuum \( c \), and Planck's constant \( h \), we can use dimensional analysis. Let's go through the steps systematically. ### Step 1: Identify the dimensions of the quantities involved 1. **Electric Charge \( e \)**: The dimension of electric charge is given by \( [e] = [I][T] \) (where \( I \) is current and \( T \) is time). 2. **Mass \( m \)**: The dimension of mass is \( [m] = [M] \). 3. **Speed of Light \( c \)**: The dimension of speed is \( [c] = [L][T]^{-1} \). 4. **Planck's Constant \( h \)**: The dimension of Planck's constant is \( [h] = [M][L]^2[T]^{-1} \). ...
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MODERN PUBLICATION-UNITS AND MEASUREMENT-COMPETITION FILE (OBJECTIVE TYPE QUESTIONS) (MCQs) (JEE MAIN OTHER STATE BOARDS FOR ENGINEERING ENTRANCE)
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  11. In terms of resistance R and time T, the dimension of ratio (mu)/(vare...

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  13. The period of oscillation of a simple pendulum is T = 2pisqrt((L)/(g))...

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  14. If electric charge e, electron's mass m, speed of light in vaccum c an...

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