Physical Quantities and Measurements Short Questions

Question 51

What is a meniscus?

Answer:
A meniscus is the curved upper surface of a liquid in a container. Water forms a concave meniscus, while mercury forms a convex meniscus.

Question 52

How should the volume of water be read in a measuring cylinder?

Answer:
Place the cylinder on a horizontal surface and keep the eye level with the meniscus. Read the scale at the bottom of waters concave meniscus.

Question 53

How can the volume of a small irregular solid be measured?

Answer:
Record the initial liquid volume in a measuring cylinder, immerse the non-dissolving solid, and record the final volume. The difference is the volume of the solid.

Question 54

What is the displacement-can method?

Answer:
The displacement-can method measures the volume of a solid too large for a measuring cylinder. The solid is immersed, and the overflowed liquid is collected and measured; its volume equals the solids volume.

Question 55

Name the three main types of experimental errors.

Answer:
The three main types are human errors, systematic errors and random errors.

Question 56

What are human errors and how can they be reduced?

Answer:
Human errors result from limitations or mistakes of the observer, such as reaction time or incorrect scale reading. Training, correct procedures and digital instruments can reduce them.

Question 57

What are systematic errors and how can they be reduced?

Answer:
Systematic errors affect measurements consistently due to causes such as zero error or poor calibration. They can be reduced through calibration, comparison with an accurate instrument and correction factors.

Question 58

What are random errors and how can they be reduced?

Answer:
Random errors cause unpredictable variations in repeated readings, often due to environmental changes. Taking several readings and calculating their average reduces their effect.

Question 59

What is uncertainty in measurement?

Answer:
Uncertainty is the unavoidable doubt about the exact value of a measurement. It arises because every measuring instrument has a limited least count and measurements are never perfectly exact.

Question 60

How can uncertainty in a small measurement be reduced?

Answer:
Measure several identical items or repeated events together and divide the total by their number. Multiple readings and averaging also reduce uncertainty.