Two waves are represented as
$y_1 = a_1\sin\left(\omega t - \dfrac{2\pi x}{\lambda}\right)$ and
$y_2 = a_2\cos\left(\omega t - \dfrac{2\pi x}{\lambda} + \dfrac{\pi}{6}\right)$
The path difference between two waves is

The equation of a wave on a string of linear mass density $0.02\ \text{kg m}^{-1}$ is $Y = 0.01\sin\left[2\pi\left(\dfrac{t}{0.02} - \dfrac{x}{0.50}\right)\right]$ m. The tension in the string is

If charge $+q$ is taken from one point to another over an equipotential surface, then

A charge $Q$ is placed at each corner of a cube of side $r$. The potential at the centre of the cube is ($\epsilon_0$ = permittivity of free space)