# Measurements and Experimentation Class-9 ICSE Concise Selina Publishers

## Chapter-1 Measurements and Experimentation Revised Concise Physics ICSE Class-9

**Measurements and Experimentation Class-9 ICSE** Concise Selina Publishers Solutions Chapter-1. Step By Step ICSE Selina Concise Solutions of Chapter-1 **Measurements and Experimentation** with Exercise-1(A), Exercise-1(B) and Exercise-1(C) including Numerical and MCQ Questions Solved **. **Visit official Website CISCE for detail information about ICSE Board Class-9.

Board | ICSE |

Publications | Selina Publication |

Subject | Physics |

Class | 9th |

Chapter-1 | Measurements and Experimentation |

Book Name | Concise |

Topics | Solution of Exe-1(A), MCQ 1(A), Numericals 1(A), Exercise-1(B), MCQ-1(B), Numericals-1(B), Exercise-1(C), MCQ-1(C) , Numericals-1(C), |

Academic Session | 2021-2022 |

## Measurements and Experimentation Class-9 ICSE Concise Selina Publishers Chapter-1

**Select Topics **

** Exercise-1(A), ****MCQ-1(A),**** ****Numericals-1(A),**

** Exercise-1(B), ****MCQ-1(B)****, ****Numericals-1(B),**

** Exercise-1(C), ****MCQ-1(C)**** , ****Numericals-1(C),**

** **Note :- Before Viewing **Selina** Concise Physics Solutions of Chapter-1 **Measurements and Experimentation Class-9** . Read the whole chapter carefully and Solved all example with Numerical s of Exercise-1 **Measurements and Experimentation Class-9. **

**Important Point for ****Measurement and Experimentation**

**Measurement and Experimentation**

International system of unit in **. **Other commonly used system of unit- FPS and CGS ,Measurement using common instrument Vernier caliper , Micrometer and screw gauge for length and simple pendulum for time **.**

Measurement of length using vernier caliper and micrometer screw gauge . least count leads count least to an increasing an accuracy least count in **Measurement and Experimentation** , Vernier caliper Screw gauge** in Measurement and Experimentation.**

**Exe-1(A) Measurements and Experimentation Class-9 Selina Physics Solutions **

**Page 9**

**Question 1**

What is meant by measurement?

**Answer 1**

Measurement is the process of comparing a given physical quantity with a known standard quantity of the same nature.

**Question 2**

What do you understand by the term unit?

**Answer 2**

Unit is a quantity of constant magnitude which is used to measure the magnitudes of other quantities of the same manner.

**Question 3**

What are the three requirements for selecting a unit of a physical quantity?

#### Answer 3

The three requirements for selecting a unit of a physical quantity are

(i) It should be possible to define the unit without ambiguity.

(ii) The unit should be reproducible.

(iii) The value of units should not change with space and time.

**Question 4**

Name the three fundamental quantities.

**Answer 4**

S.I. unit of length (m): A metre was originally defined in 1889 as the distance between two marks drawn on a platinum-iridium (an alloy made of 90% platinum and 10% iridium) rod kept at 0°C in the International Bureau of Weights and Measures at serves near Paris.

aand S.I. unit of mass (kg): In 1889, one kilogramme was defined as the mass of a cylindrical piece of a platinum-iridium alloy kept at International Bureau of Weights and Measures at serves near Paris.

while S.I. unit of time (s): A second is defined as 1/86400th part of a mean solar day, i.e.

1 s = 1/86400 × one mean solar day.

**Question 5**

Name the three systems of unit and state their various fundamental units in them.

**Answer 5**

Three systems of unit and their fundamental units:

(i) C.G.S. system (or French system): In this system, the unit of length is centimeter (cm), unit of mass is gramme (g) and unit of time is second (s).

(ii) F.P.S. system (or British system): In this system, the unit of length is foot (ft), unit of mass is pound (lb) and unit of time is second (s).

(iii) M.K.S. system (or metric system): In this system, the unit of length is meter (m), unit of mass is kilogramme (kg) and unit of time is second (s).

**Question 6**

Define a fundamental unit.

**Answer 6**

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.

**Question 7**

What are the fundamental units in S.I. system? Name them along with their symbols.

**Answer 7**

Fundamental quantities, units and symbols in S.I. system are

Quantity | Unit | Symbol |

Length | metre | m |

Mass | kilogramme | kg |

Time | second | s |

Temperature | kelvin | K |

Luminous intensity | candela | cd |

Electric current | ampere | A |

Amount of substance | mole | mol |

Angle | radian | rd |

Solid angle | steradian | st-rd |

**Question 8**

Explain the meaning of a derived unit with the help of one example

**Answer 8**

The units of quantities other than those measured in fundamental units can be obtained in terms of the fundamental units, and thus the units so obtained are called derived units.

Example:

Speed = Distance/time

Hence, the unit of speed = fundamental unit of distance/fundamental unit of time

Or, the unit of speed = metre/second or ms^{-1}.

As the unit of speed is derived from the fundamental units of distance and time, it is a derived unit.

**Question 9**

Define standard metre.

**Answer 9**

A metre was originally defined in 1889 as the distance between two marks drawn on a platinum-iridium (an alloy with 90% platinum and 10% iridium) rod kept at 0^{o}C in the International Bureau of Weights and Measures at serves near Paris.

**Question 10**

Name two units of length which are bigger than a metre. How are they related to the unit metre?

**Answer 10**

Astronomical unit (A.U.) and kilometer (km) are units of length which are bigger than a metre.

1 km = 1000 m

1 A.U. = 1.496 × 10^{11} m

**Question 11**

Write the names of two units of length smaller than a metre. Express their relationship with metre.

**Answer 11**

Centimeter (cm) and millimeter (mm) are units of length smaller than a metre.

1 cm = 10^{-2} m

1 mm = 10^{-3} m

**Question 12**

How is nanometer related to Angstrom?

**Answer 12**

1 nm = 10

**Question 13**

Name three convenient units used to measure lengths ranging from very short to very long value. How are they related to S.I. unit ?

**Answer 13**

Three convenient units of length and their relation with the S.I. unit of length:

(i) 1 Angstrom (Å) = 10^{-10} m

(ii) 1 kilometre (km) = 10^{3} m

(iii) 1 light year (ly) = 9.46 × 10^{15} m

**Question 14**

Name the S.I. unit of mass and define it.

**Answer 14**

S.I. unit of mass is ‘kilogramme’.

In 1889, one kilogramme was defined as the mass of a cylindrical piece of a platinum-iridium alloy kept at the International Bureau of Weights and Measures at serves near Paris.

**Question 15**

Complete the following

(a) 1 light year = ………..m

(b) 1 m = ………..Å

(c) 1 m = ………..µ (micron)

(d) 1 micron = ………..Å

(e) 1 fermi = ………..m

**Answer 15**

(a) 1 light year = 9.46 × 10^{15} m

(b) 1 m = 10^{10}

(c) 1 m = 10^{6} µ (micron)

(d) 1 micron = 10^{4}

(e) 1 fermi = 10^{-15} m

**Question 16**

State two units of mass smaller than a kilogram. How are they related to the unit kilogramme?

**Answer 16**

The units ‘gramme’ (g) and ‘milligramme’ (mg) are two units of mass smaller than ‘kilogramme’.

1 g = 10^{-3} kg

1 mg = 10^{-6} kg

**Question 17**

State two units of mass bigger than a kilogram. Give their relationship with the unit kilogramme.

**Answer 17**

The units ‘quintal’ and ‘metric tonne’ are two units of mass bigger than ‘kilogramme’.

1 quintal = 100 kg

1 metric tonne = 1000 kg

**Question 18**

Complete the following

(a) 1 g = ……….kg

(b) 1 mg = ……….kg

(c) 1 quintal = ……….kg

(d) 1 a.m.u (or u) = ……….kg

**Answer 18**

(a) 1 g = 10^{-3} kg

(b) 1 mg = 10^{-6} kg

(c) 1 quintal = 100 kg

(d) 1 a.m.u (or u) = 1.66 x 10^{-27} kg

**Question 19**

Name the S.I. unit of time and define it.

**Answer 19**

The S.I. unit of time is second (s).

A second is defined as 1/86400th part of a mean solar day, i.e.

1 s = × one mean solar day

**Question 20**

Name two units of time bigger than a second. How are they related to second?

**Answer 20**

Minute and hours

**Question 21**

What is a leap year?

**Answer 21**

A leap year is the year in which the month of February has 29 days.

**Question 22**

The year 2020 will have February of 29 days’.

Is this statement true?

**Answer 22**

Yes, the given statement is true.

**Question 23**

What is a lunar month?

**Answer 23**

One lunar month is the time in which the moon completes one revolution around the earth. A lunar month is made of nearly 4 weeks

**Question 24**

Complete the following

(a) 1 nanosecond =………s.

(b) 1 µs =………s.

(c) 1 mean solar day =………s.

(d) 1 year = ………s.

**Answer 24**

(a) 1 nanosecond = 10^{-9} s

(b) 1 µs = 10^{-6} s

(c) 1 mean solar day = 86400 s

(d) 1 year = 3.15 × 10^{7} s

**Question 25**

Name the physical quantities which are measured in the following units

(a) u (b) ly (c) ns (d) nm

**Answer 25**

(a) Mass (b) Distance (or length) (c) Time (d) Length

**Question 26**

Write the derived units of the following

(a) Speed (b) Force

(c) Work (d) Pressure.

**Answer 26**

(a) ms^{-1} (b) kg ms^{-2} (c) kg m^{2}s^{-2} (d) kg m^{-1}s^{-2}

**Question 27**

How are the following derived units related to the fundamental units?

(a) Newton (b) Watt

(c) Joule (d) Pascal.

**Answer 27**

(a) kg ms^{-2} (b) kg m^{2}s^{-3}

(c) kg m^{2}s^{-2} (d) kg m^{-1}s^{-2}

**Question 28**

Name the physical quantities related to the following units:

(a) km^{2} (b) Newton (c) Joule

(d) Pascal (e) Watt

**Answer 28**

(a) Area (b) Force (c) Energy

(d) Pressure (f) Power

**MULTIPLE CHOICE TYPE (EXERCISE 1-A)**

**Concise Selina Publishers Chapter-1 Measurements and Experimentation Class-9 Solutions **

**Page 10**

** ****Question 1**

The fundamental unit present in the list mentioned below is

(a) Newton

(b) Pascal

(c) Hertz

(d) Second

**Answer 1**

(d) Second

**Question 2**

Which of the following unit is not a fundamental unit:

(a) Metre

(b) Litre

(c) Second

(d) Kilogramme

**Answer 2**

(b) Litre

**Question 3**

The unit of time is

(a) Light year

(b) Parsec

(c) Leap year

(d) Angstrom.

**Answer 3**

(c) Leap year

**Question 4**

1 Å is equal to

(a) 0.1 nm

(b) 10^{-10}cm

(c) 10^{-8}m

(d) 10^{4 }µ.

**Answer 4**

(a) 0.1 nm

**Question 5**

Light year (ly) is the unit of

(a) Time

(b) Length

(c) Mass

(d) None of these.

**Answer 5**

(b) Length

** Numericals EXERCISE-1 (A) **

**Solutions of Chapter-1 Measurements and Experimentation Class-9 Revised Concise Physics Selina Publishers**

**Page 10**

**Question 1**

The wavelength of light of a particular colour is 5800 Å. Express it in (a) nanometre and (b) metre.

**Answer 1**

Wavelength of light of particular colour = 5800

(a) 1 A = 10^{-1} nm

5800 A = 5800 × 10^{-1} nm

= 580 nm

(b) 1 A = 10^{-10} m

5800 A= 5800 × 10^{-10} m

= 5.8 × 10^{-7} m

**Question 2**

The size of bacteria is 1 µ. Find the number of bacteria present in 1 m length.

**Answer 2**

Size of a bacteria = 1 µ

Since 1 µ = 10^{-6} m

Number of the particle = Total length/size of

one bacteria

= 1 m/10^{-6} m

= 10^{6}

**Question 3**

The distance of a galaxy is 5·6 × 10^{25} m. Assuming the speed of light to be 3 × 10^{8} m s “. Find the time taken by light to travel this distance .

[Hint : Time taken = distance/speed ]

**Answer 3**

Distance of galaxy = 5.6 × 10^{25} m

Speed of light = 3 × 10^{8} m/s

(a) Time taken by light = Distance travelled/speed of light

= (5.6 × 10^{25 }/ 3 × 10^{8}) s

= 1.87 × 10^{17} s

**Question 4**

The wave length of light is 589 nm. What its wavelength in Å ?

**Answer 4**

1 nm= 10 Å

589 nm = 10×589A°= 5890 Å

**Question 5**

The mass of an oxygen atom is 16.00 u. Find its mass kg.

**Answer 5**

1 amu= 1.66×10¯27 Kg

16 amu= 16×1.66×10‾27 Kg

**Question 6**

It takes time 8 min for light to reach form the sun to the earth surface . If speed of light is taken to be 3 × 10^{8} m/s, find the distance from the sun to the earth in km.

**Answer 6**

1 Min= 60sec

8 Min= 8×60 = 480sec

distance = Speed×Time

= 3×10^{8}×480

=1.44×10^{8} Km/s

**Question 7**

‘The distance of a star form the earth is 8.33 light minutes .’ What do you mean by this statements ? Express the distance in meter.

**Answer 7**

It means light take 8.33 Minute to reach the star while the speed of light is 3×10^{8} m/s.

Distance= Speed × Time

= 3×10^{8} × 8.33×60

=1.5×10^{11}Mitre

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