To determine the volume of a metallic bob
Answers
Answer:
Explanation:
Explanation:
Use of metallic bob to
(i) measure diameter of a small spherical/cylindrical body,
(ii) measure the dimensions of a given regular body of known mass
and hence to determine its density; and
(iii) measure the internal diameter and depth of a given cylindrical object
like beaker/glass/calorimeter and hence to calculate its volume.
procedure
Vernier Callipers, Spherical body, such as a pendulum bob or a glass
marble, rectangular block of known mass and cylindrical object like
a beaker/glass/calorimeter
steps:
1. A Vernier Calliper has two scales–one main scale and a Vernier
scale, which slides along the main scale. The main scale and Vernier
scale are divided into small divisions though of different
magnitudes.
The main scale is graduated in cm and mm. It has two fixed jaws, A
and C, projected at right angles to the scale. The sliding Vernier scale
has jaws (B, D) projecting at right angles to it and also the main scale
and a metallic strip (N). The zero of
main scale and Vernier scale coincide
when the jaws are made to touch each
other. The jaws and metallic strip are
designed to measure the distance/
diameter of objects. Knob P is used to
slide the vernier scale on the main
scale. Screw S is used to fix the vernier
scale at a desired position.
2. The least count of a common scale
is 1mm. It is difficult to further
subdivide it to improve the least
count of the scale. A vernier scale
enables this to be achievers
3.The difference in the magnitude of one main scale division (M.S.D.)
and one vernier scale division (V.S.D.) is called the least count of the
instrument, as it is the smallest distance that can be measured using
the instrument.
n V.S.D. = (n – 1) M.S.D.
Formulas Used
(a) Least count of vernier callipers
the magnitude of the smallest division on the main scale
the total number of small divisions on the vernier scale =
(b) Density of a rectangular body =
mass m m
volume V l.b.h = = where m is
its mass, l its length, b its breadth and h the height.
(c) The volume of a cylindrical (hollow) object V = πr2h' =
π ′2 D .h'
4
where h' is its internal depth, D' is its internal diameter and r is
its internal radius.
(a) Measuring the diameter of a small spherical or cylindrical
body.
1. Keep the jaws of Vernier Callipers closed. Observe the zero mark of
the main scale. It must perfectly coincide with that of the vernier
scale. If this is not so, account for the zero error for all observations to
be made while using the instrument as explained on pages 26-27.
2. Look for the division on the vernier scale that coincides with a
division of main scale. Use a magnifying glass, if available and
note the number of division on the Vernier scale that coincides
with the one on the main scale. Position your eye directly over the
division mark so as to avoid any parallax error.
3. Gently loosen the screw to release the movable jaw. Slide it enough
to hold the sphere/cylindrical body gently (without any undue
pressure) in between the lower jaws AB. The jaws should be perfectly
perpendicular to the diameter of the body. Now, gently tighten the
screw so as to clamp the instrument in this position to the body.
Observation;
(i) Least count of Vernier Callipers (Vernier Constant)
1 main scale division (MSD) = 1 mm = 0.1 cm
Number of vernier scale divisions, N = 10
10 vernier scale divisions = 9 main scale divisions
1 vernier scale division = 0.9 main scale division
Vernier constant = 1 main scale division – 1 vernier scale division
= (1– 0.9) main scale divisions
= 0.1 main scale division
Vernier constant (VC) = 0.1 mm = 0.01 cm
Alternatively,
1MSD Vernier constant =
N
1 mm = 10
Vernier constant (VC) = 0.1 mm = 0.01 cm