In order to take colour photograph of a planet, what kind of telescope should be used ?

Concentrated nitric acid used in laboratory work is 68% nitric acid by mass in aqueous solution. What should be the molarity of such a sample of the acid if the density of the solution is 1.504 g mL^-1 ?

A force of 7 N acts on an object. The displacement it, say 8m, in the direction of the force. Let us take it that the force acts on the object through the displacement. What is the work done in this case?

A carrier wave of peak voltage 8 v is used to transmit a message signal. What should be the peak voltage of the modulating signal in order to have a modulation index of 80%?

A fighter plane flying horizontally at an altitude of .1.5 km with speed 720 km/h passes directly overhead an anti-aircraft gun. At what angle from the vertical should the gun be fired for the shell with muzzle speed 600 m s^-1 to hit the plane? At what minimum altitude should the pilot fly the plane to avoid being hit? (Take g = 10 m s^-2) .

• Take a thick sheet of cardboard and make a small hole or narrow slit in its middle. • Allow sunlight to fall on the narrow slit. This gives a narrow beam of white light. • Now, take a glass prism and allow the light from the slit to fall on one of its faces as shown in Fig. • Turn the prism slowly until the light that comes out of it appears on a nearby screen. What do you observe? You will find a beautiful band of colours.