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INSTITUTE OF ACADEMIC EXCELLENCE AND MUSIC 421 BD, SALTLAKE CITY, KOLKATA, NEAR BD MARKET Mobile: 9874555320/9874022085 Academic year 2022-2023 Subject PHYSICS Class 12 Topics: Wave optics, current electricity Maximum Marks 30 Section A (10 marks) Time 60 min [10 1=10] 1. Two waves having the intensities in the ratio of 9 : 1 produce interference. The ratio of maximum to minimum intensity is (a) 10 : 8 (b) 9 : 1 (c) 4 : 1 (d) 2 : 1 2. In a Young s double slit experiment, the source is white light. One of the holes is covered by a red filter and another by a blue filter. In this case (a) there shall be alternate interference patterns of red and blue. (b) there shall be an interference pattern for red distinct from that for blue. (c) there shall be no interference fringes. (d) there shall be an interference pattern for red mixing with one for blue. 3. In Young s double-slit experiment, the distance between the slit sources and the screen is 1 m. If the distance between the slits is 2 mm and the wavelength of light used is 600 nm, the fringe width is (a) 3 mm (b) 0.3 mm (c) 6 mm (d) 0.6 mm 4. A potentiometer is an accurate and versatile device to make electrical measurement of EMF because the method involves (a) potential gradients (b) a condition of no current flow through the galvanometer (c) a combination of cells, galvanometer and resistance (d) cells 5. Which of the following characteristics of electrons determines the current in a conductor? (a) Drift velocity alone (b) Thermal velocity alone (c) Both drift velocity and thermal velocity (d) Neither drift nor thermal velocity 6. Why are coherent sources required to create interference of light? 7. What will be the effect on interference fringes if red light is replaced by blue light? 8. No interference pattern is detected when two coherent sources are infinitely close to each other. Why? 9. The emf of a cell is always greater than its terminal voltage. Why? Give reason. 10. Define the term Mobility of charge carries in a conductor. Write its SI unit. Page 1 of 3
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