Question

(a) 10%
(b) 0.15% (c) 1.5% (d) 2.4%.
(JEE Main 2017)
17. A screw gauge with a pitch of 0.5 mm and a circular
scale with 50 divisions is used to measure the
thickness of a thin sheet of aluminium. Before starting
the measurement, it is found that when the two jaws
of the screw gauge are brought in contact, the 45th
division coincides with the main scale line and that
the zero of the main scale is barely visible. What is
the thickness of the sheet if the main scale reading is
0.5 mm and the 25th division coincides with the main
scale line?
2
(a) 0.80 mm
(b) 0.70 mm
(c) 0.50 mm
(d) 0.75 mm.
(JEE Main 2016)
18. Resistance of a given wire is obtained by measuring the
current flowing in it and th​

Answer 1

Answer:

0.80 mm

LC=

circular scale divisions

pitch

=

50

0.5

mm=0.01mm

Negative zero error = −5×(0.01)mm=−0.05mm

Measured value = 0.5mm+25×0.01–(–0.05)mm=0.8mm