The magnetic induction along the axis of a toroidal solenoid is independent of

Optical path of a particular ray of light has travelled a distance of 3 cm in flint glass is same as that on travelling a distance ' $x$ ' cm through another medium. The value of ' $x$ ' is [refractive index of flint glass $=1 \cdot 6$, refractive index of another medium $=1.25]$

A string is under tension of 180 N and mass per unit length $2 \times 10^{-3} \mathrm{Kg} / \mathrm{m}$. It produces two consecutive resonant frequencies with a tuning fork, which are 375 Hz and 450 Hz . The mass of the string is

Two spheres of equal masses, one of which is a thin spherical shell and the other solid sphere, have the same moment of inertia about their respective diameters. The ratio of their radii is