If in a parallelogram ABDC, the coordinates of A, B and C are respectively (1, 2), (3, 4) and (2, 5), then the equation of the diagonal AD is :

The region between y = 0 and y = d contains a magnetic field $$\overrightarrow B = B\widehat z$$. A particle of mass m and charge q enters the region with a velocity $$\overrightarrow v = v\widehat i.$$ If d $$=$$ $${{mv} \over {2qB}},$$ the acceleration of the charged particle at the point of its emergence at the other side is :

In a double-slit experiment, green light (5303$$\mathop A\limits^ \circ $$) falls on a double slit having a separation of 19.44 $$\mu $$m and awidht of 4.05 $$\mu $$m. The number of bright fringes between the first and the second diffraction minima is :

Two rods A and B of identical dimensions are at temperature 30^°C. If A is heated upto 180^oC and B upto T^oC, then the new lengths are the same. If the ratio of the coefficients of linear expansion of A and B is 4 : 3, then the value of T is