Assertion: The quantity `L//R` possesses dimensions of time.
Reason: To reduce the rate of increases of current through a solenoide should increase the time constant `(L//R)`.

Options

A. Both A and R are true and R is the correct explanation of A.
B. Both A and R are true and R is NOT the correct explanation of A.
C. A is true but R is false
D. A is false and R is true

Answer

B

Explanation

For a solenoid, the magnitude of induced emf
`e = L(di)/(d t)`
`i = (e)/(R) = ((L)/(R))((di)/(d t))`
`(di)/(dt) = (i)/((L)/(R))`
In left hand side of the above equation, denominator is time. So, in right hand sie, the deominator should be time. So, dimension of L/R is time.
So, the assertion is true.
If L/R increases , di/dt decreases.
So, reason is also true.
But reason cannot properly explain the assertion.