Page 4 - 9-phy-1 Measurements

outside main scale
jaw

inside vernier screw
jaw scale

Fig. 1.1.5

2. Why is it necessary to take more than one readings and then to find the
average reading?
______________________________________________________.

3. What difficulties will you face by using a metre rod to measure the;
a. External diameter of a beaker? ________________________
________________________________________________.
b. Internal diameter of a beaker? _________________________
________________________________________________.
c. Internal depth of a beaker? ___________________________
________________________________________________.

4. What is the advantage of using vernier callipers for taking the above
measurements?

______________________________________________________.

5. How is the vernier scale related to main scale? __________________.

BRAIN TEASER

A student performed an experiment to measure the breadth of a washer as
shown. She tabulated her observations as below:

S. No. External diameter (D) in (cm) Internal diameter (d) in (cm)
1 4.18 2.96
2 4.20 2.94
3 4.17 2.95

She is puzzled now. Help her to
i) Establish a formula for breadth.
ii) Calculate the breadth

Washer

4