## class 11 physics most important question

1. Distinguish between fundamental and derived units.
2. Answer the following: a) You are given a thread and a metre. How will you estimate the diameter of the thread? b) A screw gauge has a pitch of 1.0 mm and 200 divisions on the circular scale. Do you think it is possible to increase the accuracy of the screw gauge arbitrarily by increasing the number of divisions on the circular scale? c) The mean diameter of a thin brass rod is to be measured by vernier callipers. Why is a set of 100 measurements of the diameter expected to yield a more reliable estimate than a set of 5 measurements only?
3. State the number of significant figures in the following: 0.007m2 2.64 x 1024kg 0.2370 g cm-3 6.320J 6.032 N/m2 0.0006032 m2.
4. Give the relationship between Light year and metre.
5. Write two advantages in choosing the wavelength of a light radiation as a standard of length.
6. Do A and AU stand for same length?
7. What is the difference between 4.0 and 4.000?
8. Which of the length measurements is the most accurate and why? 500.0 cm 0.0005 cm 6.00 cm.
9. Write the order of magnitude of the following numbers: (i) 146 (ii) 498 (iii) 502 (iv) 7852
10. Write at least two merits of international system of Units.
11. Define the term significant figures.
12. What is least count?
13. Name at least two physical quantities whose dimensions are [ML2T-2].
14. If x = a +bt +ct2, where x is in metres and t in second, what is the dimensional formula of C.
15. Write the full form of (i) RADAR (II) SONAR.
16. How many dynes make a Newton?
17. The length, breadth and thickness of a rectangular sheet of metal are 4.234 m, 1.005 m and 2.01 cm respectively. Give the area and volume of the sheet to correct significant figures.                    (NCERT)
18. If earth were to shrink suddenly, what would happen to the length of the day?                           (MSE (Chandigarh) 2004.
19. Write the number of significant figures in each of the following measurements: (a) 1.67 x 10-27 kg  (b) 0.270 cm.
20. Name is the S.I. unit used to express the amount of substance.                                           (KVS 2004)