`1` light year = ___________ m.

Light year is the unit of _________

Arrange the following in the descending order. 1 light year, 1 par sec, 1 astronomical unit.

Height of a plant at a certain date is 1.6m. Suppose that the height is increased by 5 cms in the following year and the height is increased in each year by half of that in the preceding year. Find the increase in height in 2nd year and 3rd year.

A ray of light undergoes refraction when it enters from air to glass. Critical angle for glass - liquid boundary is sin^1 (8/9). Determine the speed of light in liquid if speed of light in glass is 2x10^8 m/s .

A long narrow slit is illuminated by blue light and the diffraction pattern is obtained on a white screen:-In a double slit experiment, the slits are separated by 0.03 cm and the screen is placed 1.5 m away. The distance between the central fringe and the fourth bright is 1 cm. Determine the wavelength of light used in the experiment.

A tree grows at the rate of 0.5m per year. What will be the height of the board fixed at 1.5m above the base five years ago?