Ch-01: Physical Quantities and Measurement

Ch-01: Physical Quantities and Measurement
Short Questions with Answers of Chapter 01 of Physics Class 9. The first chapter of 9th Class Physics is “Physical Quantities and Measurement”. Here in this post you will find short questions with answers. Learn these short questions for exams preparation.
1: Why Is the use of zero error necessary in a measuring instrument?
Ans. By the use at "Zero Error" the observation taken can be corrected, to get a correct observation
2. What role S.I units have played in the development of Science?
Ans. S.I units are easy to use. They gave great comfort in technical information.
3. Define Plasma Physics and Geophysics.
Ans: Plasma Physics: It is the study of production, properties of the ionic state of matter -the fourth state of matter. Geophysics: it is the study of the internal structure.
4. Define derived quantities and write the name of two derived quantities.
Ans. Those physical quantities which are expressed in terms of base quantities are called the derived quantities. Names: Volume, speed.
5. Define Physics.
Ans. In Physics, we study matter-energy and their interaction.
6. Estimate your age in seconds.
My age in seventeen years: =17 x 365 x 24 x 60 x 60 = 536112000 second
7. What is meant by vernier constant?
Ans. It is the least measurement which can be made by an instrument. The vernier constant and means the value of the difference of length of one vernier division and one smallest division and main scale.
8. What do you understand by the zero error measuring instrument?
Ans: To find the zero error, close the jaws of Vernier Calipers gently. If zero line of the vernier scale coincides with the zero of the main scale then the zero error is zero. Zero error will exist if zero line of the vernier-scale is not coinciding with the zero of the main Scale. Zero error will be positive if zero line of Vernier Scale is one the right side of the zero of the main scale and will be negative if zero lines of vernier Scale is 0n the left side of zero of the main scale.
9. What is meant by derived quantities? Give an example.
Ans. Those physical quantities which are expressed in terms of base quantities are called the derived quantities. Example: Volume
10. Define the least count
Ans. The smallest reading that can be taken using a measuring instrument is called its least count.
11. What are the base units? Give an example.
Ans. The unit that describes base quantity is called the base unit. Example: Meter, Kilogram
12. What is meant by significant figures of a measurement?
Ans. All accurately known digits and the first doubtful digit of any measurement are called significant figures.
13. Define electromagnetism.
Ans. The branch of physics that deals with the study of the charges at rest and in motion, their effects and their relationship with magnetism is called electromagnetism.
14. Define plasma physics.
Ans. It is the study of production properties of the ionic State of matter - the fourth state of matter.
15 Write the difference between base quantities and derived quantities.
Ans: Base quantities: There are seven physical quantities which form the foundation for other physical quantities. These physical quantities are called the base quantities. Example: Length Derived Quantities: Those physical quantities which are expressed in term of base quantities are called the derived quantities. Example: Volume.
16. Define lease count and write metre rod's least count.
Least Count: The smallest reading that can be taken using a measuring instrument is called its least count. Metre rod’s: One millimetre is the least count of metre rod's.