Goyal Brothers Measurements and Experimentation Class-9 ICSE Physics Solutions Ch-1.  We Provide Step by Step Answer of Exercise, MCQs, Numericals Practice Problem Questions of Exercises, Subjective and Practice Problem Measurements and Experimentation Class-9, Visit official Website CISCE  for detail information about ICSE Board Class-9 Physics.

## Goyal Brothers Measurements and Experimentation Class-9 ICSE Physics Ch-1

-: Select Exercise :-

Exercise 1 (A) MCQ

(B) Subjective Questions

Unit 2 Practice Problems

Exercise 2

Unit 3 Practice Problems

Exercise 3

Unit 4 Practice Problems

Exercise 4

Unit 5 Exercise 5

Unit 6

Exercise 6

Unit 7 Exercise 7

### (A) Objective Questions

Exe-1 Measurements and Experimentation Class-9 Goyal Brothers ICSE Physics Solutions Ch-1

I. Multiple choice Questions.
Select the correct option:

1. Which of the following is not a fundamental unit?
(a) Second
(b) Ampere
(c) Candela
(d) Newton
Ans. (d) Newton
Explanation : Second, Ampere and Candela are the fundamental units while Newton is a derived unit.

2. Which of the following is a fundamental unit?
(a) m/s2
(b) Joule
(c) Newton
(d) metre
Ans. (d) metre
Explanation : m/s2, Joule and Newton are derived units while metre is a fundamental unit.

3. Which is not a unit of distance?
(a) metre
(b) millimetre
(c) Leap year
(d) kilometre
Ans. (c) Leap year
Explanation : Leap year is a unit of time while the metre, millimetre and kilometre are the units of distance.

II Fill in the blanks

1. The unit is which we measure the quantity is called constant quantity.
2. One light year is equal to 9.46 × 1015 m.
3. One mean solar day = 86400 sec
4. One year = 3.1536 × 107 sec
5. One micrometre = 10-6 m.

(B) Subjective Questions

### Exe-1 Measurements and Experimentation Class-9 Goyal Brothers ICSE Physics Solutions Ch-1

Question 1.
What do you understand by the term measurement?
“Measurement implies comparison of a physical quantity with a standard unit to find out how many times the given standard is contained in the physical quantity.”
Physics, like other branches of science requires experimental study which involves measurement.

Question 2.
What do you understand by the terms

1. unit
2. magnitude, as applied to a physical quantity?

(i) Unit : Unit “is a standard quantity of the same kind with which a physical quantity is compared for measuring it. ” In order to measure a physical quantity, a standard is needed (which is acceptable internationally). The standard should be some convenient, definite and easily reproducible quantity of the same kind in terms of which the physical quantity as a whole is expressed. This standard is called a unit
(ii) Magnitude of a physical quantity : The number of times a standard quantity is present in a given physical quantity is called magnitude of physical quantity.
Physical quantity = Magnitude × Unit

Question 3.
A body measures 25 m. State the unit and the magnitude of unit in the statement.
Here S.I. unit of length i.e. metre (m) has been used. Magnitude of the given quantity = 25
Metre : It is defined as 1,650,763,73 times the wavelength of specified orange red spectral line a emission spectrum of Krypton-86 or 1,553,164.1 times the wavelength of the red line in emission spectrum of cadmium.
or one metre is defined as the distance travelled by the light in 1/299,792,458 of a second in air/vacuum.

Question 4.
State four characteristics of a standard unit.
Characteristics of standard unit :

1. It should be of convenient size.
2. It should not change with respect to place and time.
3. It should be well defined.
4. It should be easily reproduced.

Question 5.
Define the term fundamental unit. Name fundamental units of mass; length; time; current and temperature.
Fundamental unit : A fundamental or basic unit is that which is independent of any other unit or which can neither be changed nor can be related to any other fundamental unit. e.g. units of mass, length, time and temperature. Question 6.
What do you understand by the term derived unit? Give three examples.
Derived units. “Derived units are those which can be expressed in terms of fundamental units.”
Example.  2. S.I. unit of area i.e. m2 is a derived unit.
Now metre is unit of length and breadth, so S.I. unit of area is obtained by multiplying the fundamental unit ‘m’ with itself. So, m2 is the derived unit of area.
3. Density = Mass/volume
S.I. unit of density i.e. kg/m3 is the derived unit of density because it can be obtained by combining two fundamental units kilogram and metre.

Question 7.

(a) Define metre according to old definition.
(b) Define metre in terms of wavelength of light.
(c) Why is the metre length in terms of wavelength of light considered more accurate?

(a) Metre : One metre is defined as the one ten millionth part of distance from the pole to the equator.
(b) Metre : One metre is defined as 1,650, 763.73 times the wavelength of specified orange red spectral line in emission spectrum of Krypton = 86.
OR
One metre is defined as 1,553,164.1 times the wavelength of the red line in emission spectrum of cadmium.
(c) Metre length in terms of wavelength of light is considered more accurate because

1. The wavelength of light does not change with time, temperature, pressure etc.
2. It can be reproduced anywhere at any time because Krypton is available every where.

Question 8.
Name the convenient unit you will use to measure :

(a) length of a hall
(b) width of a book
(c) diameter of hair
(d) distance between two cities.

(a) Foot (Ft)
(b) Centimetre (cm)
(c) Micrometre (µm)
(d) Kilometre (km)

Question 9.
(a) Define mass.
(b) State the units in which mass is measured in (1) C.GS. system (2) S.I. system.
(c) Name the most convenient unit of mass you will use to measure :

1. Mass of small amount of a medicine.
2. The grain output of a state
3. The bag of sugar
4. Mass of a cricket ball.

(a) Mass: The quantity of matter contained in a body is known as its mass.
(b) In C.GS. system, mass is measured in gram. In S.I. system, mass is measured in Kilogram. Question 10.
(a) Define time.
(b) State or define the following terms :

1. Solar day
2. Mean solar day
3. An hour
4. Minute
5. Second
6. Year.

(a) Time : It is defined as the time interval between two events
(b)
(i) Solar day : The time taken by the earth to complete one rotation about its own axis is called solar day.
(ii) Mean solar day : The average of the varying solar days, when the earth completes one revolution around the sun, is called mean solar day.
(iii) An hour : It is defined as the 1/24 th part of the mean solar day.
(iv) Minute : It is defined as the 1/1440 part of the mean solar day.
(v) Second : “A second is defined as 1/86400 th part of a mean solar day.”
OR
Second may also be defined “as to be equal to the duration of9,192,631,770 vibrations corresponding to the transition between two hyperfme levels of caesium – 133 atom in the ground state.”
(vi) Year : One year is defined as the time in which earth completes one complete revolution around the sun.

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