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 ?

A screw gauge has a pitch of 0.5 mm, and has 50 divisions on its circular scale. Its linear and circular scale readings are respectively 2 mm and 25 when the diameter of a sphere is measured by the gauge. The result of this measurement is

When the diameter of a wire is measured by a screw gauge the main scale and the circular scale readings are 0 mm and 52 respectively. Given screw pitch = 1mm and number of divisions on the circular scale = 100. Find out the diameter of the wire.

The circular scale of screw gauge has 100 equal divisions. Its screw pitch is 1 mm. This gauge measures the diameter of a wire of length 5.6 cm. The main scale and the circular scale readings are observed to be 1 mm and 47 respectively. Calculate the area in cm^(2) of the curved surface of the wire keeping the significant figures only.

A mercury thermometer contains 0.4cm^(3) of mercury at 0^(@)C. The diameter of the capillary tube of the thermometer is 0.2 mm. What should be the length of the scale to measure temperatures between 0^(@)C " to " 100^(@)C ? The coefficient of apparent expansion of mercury =1.7 times 10^(-4@)C^(-1).

20 vernier divisions coincide with 19 main scale divisions of a vernier. The smallest main scale division is 0.5 mm. When it measures the side of a cube the main scale and the vernier readings are 10 mm and 2, respectively. If the mass of the cube is 2.736 g, find out the density of its material keeping the significant digits only.

The internal resistance of a battery of e.m.f. 100 Vis 4 Omega . A voltmeter of resistance 250 Omega is used to measure the e.m.f. of the battery. What should be the minimum value of the voltmeter resistance so that the error in finding the e.m.f. of the battery may not be more than 1 percent?