A dimensionless quantity is constructed in terms of electronic charge π, permittivity of free space π0, Planckβs constant β, and speed of light π. If the dimensionless quantity is written as ππΌπ0 π½βπΎππΏ and π is a non-zero integer, then (πΌ, π½, πΎ, πΏ) is given by
Correct Answer :
(2π, βπ, βπ, βπ)
Solution :
The correct option is (2n, -n, -n, -n).
To find the values of , , , and such that the quantity is dimensionless, we can write down the dimensions of each fundamental quantity in terms of Mass (M), Length (L), Time (T), and Electric Current (A).
Let's find the dimensional formula for each parameter:
1. Electronic charge ():
Charge is current multiplied by time.
2. Permittivity of free space ():
From Coulomb's Law, the electrostatic force between two charges is , which gives .
Thus, the dimensions of are:
3. Planckβs constant ():
From the relation , where is energy and is frequency:
4. Speed of light ():
Now, we write the dimension of the given quantity:
Substituting the dimensional formulas, we get:
Grouping the powers for each base unit:
Mass ():
Length ():
Time ():
Current ():
From , let's substitute this into the equation for Length:
Let's check the Time equation with these substitutions:
This is consistent, meaning any non-zero value can be used as a scaling factor.
If we set (where is a non-zero integer), we obtain:
Therefore, the coordinates are given by .
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