**Samacheer Kalvi Class 8 Science Unit 1 Measurement Solutions**

**Samacheer Kalvi Class 8 Science Unit 1 Measurement Solutions**

Welcome to NCTB Solutions. Here with this post we are going to help 8th class students by providing Solutions for Samacheer Kalvi Class 8 Science Unit 1 Measurement. Here students can easily find all the solved solution for Measurement Exercise questions. Also here our Expert Science Teacher’s solved all the questions with easily understandable language with proper guidance so that all the students can understand easily. Here on this post students will get Unit 1 Measurement exercise solutions. Here all the solutions are based on Tamil Nadu State Board latest syllabus.

*Unit 1 Measurement Exercise Questions Solutions :*

*Unit 1 Measurement Exercise Questions Solutions :*

**(I) Choose the best answer : **

**(1) Which one the following systems of unit is the British System of unit**

**(a) CGS**

**(b) MKS**

**(c) FPS**

**(d) SI**

**Answer :**

Correct Option → (c)

The British System of unit was known as FPS.

**(2) Electric current is a** ____** quantity**

**(a) base**

**(b) supplementary**

**(c) derived**

**(d) professional**

**Answer :**

Correct Option → (a)

Electric current is a base quantity.

**(3) SI unit of temperature is ______**

**(a) celsius**

**(b) fahrenheit**

**(c) kelvin**

**(d) ampere**

**Answer :**

Correct Option → (c)

SI unit of temperature is Kelvin.

**(4) Luminous intensity is the intensity of ____**

**(a) laser light**

**(b) UV light**

**(c) visible light**

**(d) IR light**

**Answer :**

Correct Option → (c)

Luminous intensity is the intensity of visible light.

**(5) Closeness of two or more measured values is called as ___**

**(a) accuracy**

**(b) precision**

**(c) error**

**(d) approximation**

**Answer :**

Correct Option → (a)

Closeness of two or more measured values is called as Accuracy.

**(6) Which one of the following statement is wrong?**

**(a) Approximation gives accurate value.**

**(b) Approximation simplifies the calculation.**

**(c) Approximation is very useful when little information is available.**

**(d) Approximation gives the nearest value only.**

**Answer :**

Correct Option → (d)

Approximation gives the nearest value only.

**(II) Fill in the blanks.**

**(1) The solid angle is measured in** ___

**(2) The coldness or hotness of a substance is expressed by** ___

**(3)** ___** is used to measure electric current.**

**(4) One mole of a substance contains** ___** atoms or molecules.**

**(5) The uncertainty in measurement is called as** ___

**(6) The closeness of the measured value to the original value is** ___

**(7) The intersection of two straight lines gives us** ___

**Answer :**

(1) → Steradian

(2) → temperature

(3) → Ammeter

(4) → 6.022 into 10- 23

(5) → Standard uncertainty

(6) → accuracy

(7) → plane angle

**(III) State true or false. If false, correct the statement.**

**(1) Temperature is a measure of total kinetic energy of the particles in a system.**

**(2) If one coulomb of charge is flowing in one minute, it is called ‘ampere’.**

**(3) Amount of substance gives the number of particles present in a substance.**

**(4) Intensity of light coming from a candle is approximately equal to one ‘candela’.**

**(5) Quartz clocks are used in GPS devices.**

**(6) Angle formed at the top of a cone is an example for ‘plane angle’.**

**(7) The number 4.582 can be rounded off as 4.58.**

**Answer :**

(1) → True

(2) → False,

Because, if one coulomb of charge is flowing in one second then it is called Ampere.

(3) → True

(4) → True

(5) → False

Because, Atomic clock are used in a GPS.

(6) → False

Because, angle formed at the top of a cone is an example for steradian.

(7) → True

**(VI) Answer very briefly.**

**(1) How many base quantities are included in SI system?**

**Answer :**

length, mass, time, temperature, electric current, amount of substance and luminious intensity are the base quantities include in SI system.

**(2) Give the name of the instrument used for the measurement of temperature.**

**Answer :**

“Thermometer” is used for the measurement of temperature.

**(3) What is the SI unit of luminous intensity?**

**Answer :**

Candela is the SI unit of luminous intensity

**(4) What type of oscillations are used in atomic clocks?**

**Answer :**

Periodic vibrations is used in atomic clocks.

**(5) Mention the types of clocks based on their display.**

**Answer :**

There are two types of clocks based on their display –

(1) Analog clocks

(2) Digital clocks.

**(6) How many times will the ‘minute hand’ rotate in one hour?**

**Answer :**

A minute hand of a clock makes a complete revolution in one hour.

**(7) How many hours are there in a minute?**

**Answer :**

0.0167 hours are there in a minute.

**(VII) Answer briefly.**

**(1) What is measurement?**

**Answer :**

Measurement is the measurement of the physical quantities. Measurement is the base of all scientific studies and experimentations. Measurements have different units.

**(2) Name the three scales of temperature.**

**Answer :**

The name of the three scales of temperature are

- Celsius,
- Fahrenheit
- Kelvin

**(3) Define – Ampere.**

**Answer :**

One coulomb of charge is flowing through a conductor in one second then the amount of current flowing is said to be one ampere. Ampere is the device used to measure electric current.

**(4) What is electric current?**

**Answer :**

Flow of electric charges in a particular direction is known as Electric current.

**(5) What do you mean by luminous intensity?**

**Answer :**

The measure of the power of the emitted light by a light source in a particular direction per unit solid is called as luminous intensity.

**(6) Define – Mole.**

**Answer :**

It is the unit in SI system , the number of atoms or molecules in a substance is measured in that is known as mole.

**(VIII) Answer in detail.**

**(1) List out the base quantities with their units.**

**Answer :**

Quantity : |
Unit : |
Symbol : |

• Length | • Metre | • m |

• Mass | • Kilogram | • Kg |

• Time | • Second | • S |

• Temperature | • Kelvin | • K |

• Electric current | • Ampere | • A |

• Amount of substance | • Mole | • Mol |

• Luminous intensity | • candela | • Cd |

**(2) Write a short note on different types of clocks.**

**Answer :**

There are main two types of clocks display and working clocks. Clocks are used to measure time intervals. Display clocks are the two types –

**(a) Analog clocks** : This type of clocks are the classic clocks. They have three hands to show time. Hours hands, minutes hands and seconds hands.

**(b) Digital clocks** : They show time directly. This type of clocks shows time in numerals or other symbols. This type of clocks may have 12 hrs or 24 hours display. This clocks are also called electronic clocks.

The second types of clocks are working clocks. It also have two types –

**(a) Quartz clock** : There clocks are activated by electronic oscillations, which are controlled by a quartz crystal. Quartz clock is more accurate than mechanical clock.

**(b) Atomic clock** : There clocks make use of periodic vibrations occurring within the atom. This type of clocks are used in GPS system and international time distribution services.

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