STUDY MATERIAL : QUESTION BANK FOR STUDENTS OF CLASS XII CBSE (Science)

QUESTION BANK FOR STUDENTS OF CLASS XII CBSE : MAGNETIC EFFECT OF CURRENT AND MAGNETISM
1. Write two properties of a material used as a suspension wire in a moving coil galvanometer.
2. An electron is projected along the +ve X axis. It experiences a force due to a magnetic field along the +ve Y axis. What is the direction of the magnetic field?
3. An electric current is flowing due south along a power line. What is the direction of the magnetic field (a) above it and (b) below it?
4. Which one of the two - an ammeter and a milliammeter- has greater resistance? explain.
5. What is the advantage of using a radial magnetic field in a moving coil galvanometer?

QUESTION BANK FOR STUDENTS OF CLASS XII CBSE : RAY OPTICS AND OPTICAL INSTRUMENTS
1. How is fluorescence different from phosphoresence?
2. Ray optics is a limiting case of wave optics. Comment.
3. Explain the cause of dispersion.
4. Why dispersion is not observed when light passes through a glass slab?
5. Vehicle moving in foggy weather uses yellow head lamps. Why?
6. Can the absolute value of a medium be less that unity? Justify your answer.
7. Explain the blue colour of sky.
8. When a number of persons are viewing rainbow simultaneously each of them has a personal rainbow. Comment/ Explain.

QUESTION BANK FOR STUDENTS OF CLASS XII CBSE : WAVE OPTICS
1 MARK QUESTIONS
1. If the angle between the polariser and analyser is 45º, write the ratio of the original incident light to that of the light tyransmitted after passing through the analyser.
2. Draw a graph showing the variation of intensity of polarised light transmitted by an analyser.
3. What is the polarising angle of a medium of refractive index 1.732?
4. Sketch the refracted wave front emerging from a convex lens if a plane wave front is incident normally on it.
5. Give the ratio of velocities of light rays of wave lengths 4000 A and 8000 A in vacuum.
6. Unpolarised light of intensity Io is passed through a polaroid. What is the intensity of the light coming out of the polaroid?
7. Write differences between interference and diffraction.
8. What is the cause of diffraction?
9. Why longitudinal waves cannot be polarised?
10. Why narrow sources are to be used for producing interference?
11. Two slits in Young's double slit experiment have widths in the ratio 81:1. What is the ratio of the amplitudes of light waves from them?
12. In Young's double slit experiment, light from each source has an intensity Io. What is the intensity at a point where constructive interference?
13. Light from two coherent sources of same amplitude reaching at a point differ in path by 3(lamda)/2. What will be the colour of fringe at this point?
14. What will be the effect on the width of fringes formed in Young's Double Slit experiment, if the entire apparatus is immersed in water?
15. Can we get white light to get sustained interference pattern? Explain.

2 MARK QUESTIONS
1. The ratio of intensities of maxima and minima in an interference pattern is 100:64 . Calculate the ratio of the intensites of the coherent sources producing this pattern.
2. A slit of width 'd' is illuminated by light of wavelength 5000 Å. For what value of d will the first secondary maximum fall at an angle of diffraction of 30 degree?
3. How does diffraction limit the resolving power of an optical instrument?
4. Why two independent souces even of same frequency and amplitude cannot be coherent?
5. For what distance from an aperture of width 3 mm, the rectilinear propagation of light of wavelength 500 nm can be considered valid?

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