Physical Quantities & Measurement

Question 1

what is the SI unit of energy?

Answer 1

The SI unit of energy is Joule (J).

Question 2

What is Physics?

Answer 2

Physics is the study of matter and energy and the mutual relation between them.

Question 3

What are physical quantities?

Answer 3

The quantities which can be measured are called physical quantities & consists of a magnitude and unit.

Question 4

Name the physical quantities.

Answer 4

mass (kg)
Time (s)
length (m)
temp. (K)
current (A)
intensity of light (cd)
amount of substance (mol)

Question 5

what are base quantities?

Answer 5

base quantities form the base or foundation of other physical quantities. All other physical quantities are derived from them.

Question 6

what are derived physical quantities?

Answer 6

derived quantities are expressed in terms of base quantities.

Question 7

what is a numerical magnitude?

Answer 7

Numerical magnitude is the number representing the size of the quantity

Question 8

what is a unit?

Answer 8

A unit is a standard with which physical quantities are compared.

Question 9

what are base units?

Answer 9

in si seven physical quantities are chosen as base and their units are defined and standardized. theses units are called base units. Each SI unit is defined carefully so that accurate and reproducible measurements can be made.

Question 10

what are derived units?

Answer 10

The units used to measure derived quantities are called derived units. units of derived quantities are obtained by multiplying or dividing base units. Derived units are expressed in terms of base units.

Question 11

what is scientific notation?

Answer 11

SN is an easy method of writing very small or very large numbers in the power of ten. In SN a no. is expressed in some power to ten multiplied by a number between 1 and 10

Question 12

what is mantissa?

Answer 12

part of a number located after a decimal point.

Question 13

what are prefixes?

Answer 13

Si units have the advantage that their multiples and sub-multiples can be expressed in terms of prefixes. A mechanism through which numbers expressed in the power of ten are given a proper name is called prefixes. Prefixes are useful for expressing units of physical quantities that are either very large or very small.

Question 14

What are measuring instruments?

Answer 14

Measuring instruments are used to measure various physical quantities such as length, mass time etc

Question 15

What is a metre rule?

Answer 15

A meter rule is a length-measuring instrument that is one meter long. It is used to measure the length of objects or the distance between two points. It is equal to 100 cm. Each cm is divided into 10 mm. Thus, 1 mm is the smallest reading that can be taken using a meter rule and is called its least count.

Question 16

what is a measuring tape?

Answer 16

Measuring tapes are used to measure the length in meters and cm. A measuring tape consists of a thin and long strip of cotton, metal, or plastic generally 10m, 20m, 50m, or 100m long. Measuring tapes are marked in cm as well as in inches.

Question 17

prefixes in order with a power of ten.

Question 18

what is a vernier caliper?

Answer 18

a measuring device that is used for the measurement of linear dimensions. A Vernier caliper can help take a reading smaller than a millimeter. It can measure the thickness, diameter, or width of an object and the internal and external diameter of a hollow cylinder.
A Vernier caliper consists of two jaws. One is a fixed jaw with a main scale attached to it. The main scale has centimeter and millimeter marks on it. The other is a movable jaw. There are two scales on Vernier Caliper. The main scale has markings of usually 1 mm each and it contains a jaw on its left end.
A sliding scale called the vernier scale is marked with divisions slightly smaller than the division of the main scale.
For example, a vernier scale could have 11 markings for each 10 on the main scale. That’s 10 divisions on the vernier scale for every 9 on the main scale.

Question 19

What is zero error and zero correction?

Answer 19

On closing the jaws of the Vernier Caliper, the zero of the vernier scale should coincide with the zero of the main scale. if their zeros do not coincide, there is an error in the instrument called a zero error.

Question 20

steps for taking reading on a scale

Question 21

when is the zero error positive

Answer 21

when zero line of VS is on the right side of the zero of the MS

Question 22

what is the zero error called when the zero of the VS is on the left side of the zero of the MS?

Answer 22

Negative zero error

Question 23

when do we have to add or subtract measurement with zero error?

Answer 23

if +ve zero error subtract it from the measurement
if -ve zero error, add it with the measurement.

Question 24

what does the accuracy of measuring significant figures depend on?

Answer 24

the quality of the measuring instrument.
the skill of the observer
the number of observations made

Question 25

what are the types of value?

Answer 25

2 types
exact and measured

Question 26

what is a significant figure?

Answer 26

all the accurately known figures and the first doubtful figure in measurement are termed as significant figures. A significant figure is a number that is believed to be correct with some uncertainty only in the last digit.

Question 27

how to find the least count of the vernier caliper?

Answer 27

the smallest reading on the main scale/total no. of divisions on the vernier scale.

Question 28

what is a stopwatch?

Answer 28

stopwatch is used to measure the time interval of an event. There are 2 types: mechanical and digital stopwatch.

Question 29

a mechanical stopwatch can measure the time interval up to_________?

Answer 29

0.1 second

Question 30

a digital stopwatch can measure the time interval up to_________?

Answer 30

0.01 second or 1/100

Question 31

how to use a mechanical stopwatch?

Answer 31

It has two circular dials, a large circular dial in which the second hand of the watch rotates, and a small circular dial in which the minute hand of the watch rotates.

Question 32

how to use a digital stopwatch?

Question 33

mechanical stopwatch is also called a?

Answer 33

analogue stopwatch

Question 34

how to measure the VOLUME of irregular shaped solid?

Question 35

the meniscus of most liquids curves ________?

Answer 35

downwards

Question 36

the meniscus of mercury curves ________?

Answer 36

upwards

Question 37

how to use a measuring cylinder?

Question 38

when the eye is above the liquid level ___________________

Answer 38

the meniscus appears higher than the actual height of the liquid

Question 39

when the meniscus appears lower on the scale?

Answer 39

when the eye is below the liquid level.

Question 40

what is a measuring cylinder?

Answer 40

A measuring or graduated cylinder is made from transparent glass or plastic. It has a scale along its length that indicates the volume in milliliters (mL) or (cm3). Measuring cylinders have different capacities from 100 mL to 2500 mL. They are used to measure the volume of a liquid or powdered substance. The vol. of the liquid can be found by measuring the height of the liquid.

Question 41

what is the least count of measuring cylinders?

Answer 41

1cm3 or 1mL

Question 42

what is zero correction?

Answer 42

Knowing the zero error, necessary corrections can be made to find the correct measurement. Such a correction is called zero correction of the instrument. Zero correction is the negative of zero error.

Question 43

what can a vernier caliper measure?

Answer 43

It can measure the thickness, diameter, or width of an object and the internal and external diameter of a hollow cylinder.

Question 44

what can a vernier caliper measure?

Answer 44

It can measure the thickness, diameter, or width of an object and the internal and external diameter of a hollow cylinder.

Question 45

how many scales are there in the vernier caliper?

Answer 45

There are two scales on Vernier Caliper.
The main scale has markings of usually 1 mm each and it contains a jaw on its left end.
A sliding scale called the vernier scale is marked with divisions slightly smaller than the division of the main scale.