Page 17 - Physics - XI

Q14. When is the zero error positive?
Ans. Zero error is positive if the zero of Vernier scale lies towards the right side of the zero of the main
scale when the two jaws are in contact.

Q15. When is the zero error negative?
Ans. The zero error is negative if the zero of Vernier scale lies towards the left side of the zero of the main
scale when the two jaws are in contact.

Q16. How is the zero error applied?
Ans. Zero error is algebraically subtracted from the observed reading.

Q17. What is the zero correction and how is it applied?
Ans. Negative of zero error is called zero correction and it is algebraically added to the observed reading.

Q18. Which one will be more accurate—a calliper with a small V.C. or a calliper with a large V.C.?
Ans. A calliper with a small V.C.

Q19. What is the function of the sliding strip?
Ans. It is used to measure the depth of the calorimeter/beaker.

Q20. What is the function of upper jaws of the Vernier Callipers?
Ans. Upper jaws are used to measure the internal diameter of hollow vessels, e.g. the internal diameter
of a calorimeter.

Q21. One can understand an exercise to know the level of skills developed in making measurements
using Vernier Calliper. Objects such as bangles/Kangans, marbles whose dimensions can be
measured indirectly using a thread can be used to judge the skill acquired through comparison
of results obtained using both the methods. (NCERT)
Ans. The dimensions of bangles/kangans and marbles can be measured by using a thread and a Vernier
Calliper. But a Vernier Calliper will give the measurement more correctly than a thread.

Q22. How does a vernier decrease the least count of a scale? (NCERT)
Ans. The least count of a Vernier Calliper can be decreased by increasing the number of divisions on
Vernier scale.

EXPERIMENT - 2

Aim

To measure diameter of a given wire and thickness of a given sheet using screw gauge.

Apparatus and Materials Required

Screw gauge, wire, half-metre scale, metallic sheet, and a pencil

Description of the Measuring Device
Screw Gauge: We can measure the length accurately up to 0.1 mm with the help of Vernier Callipers. To
measure the length accurately up to 0.01 mm or 0.005 mm, we use a screw gauge. Thus, a screw gauge is

an instrument of higher precision than a Vernier Calliper.

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