There are two sources kept at distances 2λ. A large screen is perpendicular to the line joining the sources. Number of maxima on the screen in this case is (λ= wavelength of light)
A particle is moving in a straight line. The variation of position $ x $ as a function of time $ t $ is given as: $ x = t^3 - 6t^2 + 20t + 15 $. The velocity of the body when its acceleration becomes zero is: