When a particle executes SHM, the nature of graphical representation of velocity as a function of displacement is :

The period of oscillation of a simple pendulum is $$T = 2\pi \sqrt {{L \over g}} $$. Measured value of 'L' is 1.0 m from meter scale having a minimum division of 1 mm and time of one complete oscillation is 1.95 s measured from stopwatch of 0.01 s resolution. The percentage error in the determination of 'g' will be :

A soft ferromagnetic material is placed in an external magnetic field. The magnetic domains :

Which of the following equations represents a travelling wave?