FSc Part 1 Measurements Short Questions

 

FSc Part 1 Measurements Short Questions. Find the most important and conceptual short questions along with their answers of Physics, FSc | ICS Part-1 Chapter No.1: Measurements. The following questions are specially selected for the examinations; and job interview questions:

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➤ Measurements - MCQs-1
➤ Measurements - MCQs-2
➤ Measurements - MCQs-3
➤ Measurements - Short Questions-I

 

Chapter No.1: Measurements 
Short Questions & Answers

Q. 1: Does a dimensional analysis give any information on the constant of proportionality that may appear in an algebraic expression? Explain.

Answer:

The dimensional analysis does not give any information about the constant of proportionality or dimensionless constant. For example:

`V="Constant" \times\sqrt\frac{E}{p}`

 

Q. 2: Write the dimension of:

• Pressure

• Density

Answer:

Dimensions of Pressure:

As `P=\frac{F}{A}=\frac{ma}{A}`

Unit of `P=\frac{"kg" ms^{-2}}{m^2}`

`=kg m^{-1} s^{-2}`

`\Rightarrow [P]=[ML^{-1}T^{-2}]`

Dimensions of Density:

As `Density=\frac{Mass}{Volume}`

Unit of density `= \frac{kg}{m^3}=kgm^{-3}`

`[Density]=[ML^{-3}]`

 

Q. 3: The wavelength `\lambda` of a wave depends on the speed v of the wave and its frequency f. Knowing that

`[\lambda]=[L],[v]=[LT^{-1}] and [f]=[T^{-1}]`

Decide which of the following is correct:

`f=v \lambda` or `f=\frac{v}{ \lambda}`

Answer:

In 1^st case if: 

`f=v \lambda` where f is frequency. Its dimension is `[T^{-1}]`, v is speed, its dimensions are `[LT^{-1}]`.

`\lambda` is the wavelength, its dimension is [L].

So `[T^{-1}]=[LT^{-1}][L]`

`[T^{-1}]=[L^2T^{-1}]`

Hence the equation `f=v\lambda` is not dimensionally correct.

In 2^nd case if:

`f=\frac{v}{\lambda}`

So `[T^{-1}]=\frac{[LT^{-1}]}{[L]}`

`[T^{-1}]=[T^{-1}]`

Hence the equation `f=\frac{v}{\lambda}` is dimensionally correct.

 

Q. 4: Define physics?

Answer:

The study of matter and energy and the relationship between them is called physics.

 

Q. 5: What are physical quantities, give its types?

Answer:

All those quantities in terms of which laws of physics can be described and whose measurement is necessary to understand any problem are called physical quantities. These are called physical quantities. There are two types:

• Basic quantities

• Derived quantities

 

Q. 6: What do you know about the international system of units?

Answer:

In 1960, the international committee agreed on a set of definitions and standards to describe the physical quantities. The system that was established by this committee is called the system international (SI).

 

Q. 7: Name the supplementary units?

Answer:

Supplementary units are:

• Radian

• Steradian

 

Q. 8: Convert 0.0023 into scientific notation?

Answer:

`0.0023=\frac{23}{10000}`

`=\frac{2.3}{1000}`

`2.3\times10^{-3}`

 

Q. 9: How many meters are there in one light-year?

Answer:

Speed of light  = C      = `3\times10^8` m/sec.

Time                = t        = 31536000 sec.

Distance          = S      = ?

S          = Ct

            = `3\times10^8\times31536000`

            = `9.5\times10^{15}` m

 

Q. 10: How do you check a formula for dimensional consistency?

Answer:

For checking dimensional consistency, write both sides of the formula to base units and compare these units. If the units of both sides are equal then the formula is dimensionally consistent.

 

Q. 11: State the principle of homogeneity of dimensions?

Answer:

In order to check the correctness of an equation, we are to show that the dimensions of the quantities on both sides of the equation are the same, irrespectively of the form of formula. This is called the principle of homogeneity of dimensions.

 

Q. 12: What do you mean by a unit?

Answer:

A unit is a standard that is used for the measurement of a physical quantity.

 

Q. 13: Write down the two points that should be kept in mind while using units?

Answer:

The following two points should be kept in mind while using units:

• The symbol of the unit named after a scientist has initial capital letters e.g., N for Newton.

• A combination of base units must be written each with one space apart such as Newton meter must be written as N-m.

 

Q. 14: What is the dimension of angle?

Answer:

Using the relation

`S=r\theta`

Where S is the length of an arc, r is the radius and `\theta` is the angular displacement, therefore

`\theta = \frac{S}{r}`

The dimension of S is [L] and the dimension of r is [L].

Then    `[\theta] = \frac{[L]}{[L]}`

`\theta` = 1

So the angular displacement is a ratio hence it is dimensionless.

 

Q. 15: What is a standard kilogram made of?

Answer:

The standard kilogram is made up of an alloy of 90% platinum and 10% iridium.