PHYSICS MOCK TEST TIME 45MIN MARKS 30
(i) What kind of source produces a cylindrical wave front?
(ii) On which factors does the deviation produced by a thin prism depend?
(iii) A convex lens forms a virtual image of an object. Where is the object? Answer in terms of focal length.
Section – B
(Answer all questions)
Question – 1
a) How are the electric vector E and magnetic vector B and velocity vector C oriented in an electromagnetic wave? 
b) The distance between the first and sixth bright fringes formed in Young’s double slit experiment is found to be 12.5 mm. The separation between the slit is 0.12 mm and the distance of the screen from the slits is 60 cm. Calculate (i) the fringe width, (ii) the wavelength of light used (in mm) 
c) What is a Polaroid? What is meant by (i) plane polarizing light and (ii) polarizing angle? 
Question – 2
a) Derive Lens Maker’s Formula. 
b) A glass lens is immersed in water. Will its power increase or decrease? 
c) When two thin lengths f1 and f2 are kept in contact, prove that their combined focal length f is given by 1/f= 1/f1+1/f2. 
Question – 3
a) Explain the phenomenon of total internal reflection with neat ray diagrams. 
b) Derive the condition for two thin lenses placed coaxially in contact so as to form an achromatic combination. Why are lenses of opposite nature used to form an achromatic lens combination? 
c) An astronomical telescope is adjusted to form the final image at infinity. The separation between the lenses is 80 cm. The angular magnification is 15. Calculate the focal lengths of the objective lens and eyepiece.