Physical Quantities & Measurement Flashcards
what is the SI unit of energy?
The SI unit of energy is Joule (J).
What is Physics?
Physics is the study of matter and energy and the mutual relation between them.
What are physical quantities?
The quantities which can be measured are called physical quantities & consists of a magnitude and unit.
Name the physical quantities.
mass (kg)
Time (s)
length (m)
temp. (K)
current (A)
intensity of light (cd)
amount of substance (mol)
what are base quantities?
base quantities form the base or foundation of other physical quantities. All other physical quantities are derived from them.
what are derived physical quantities?
derived quantities are expressed in terms of base quantities.
what is a numerical magnitude?
Numerical magnitude is the number representing the size of the quantity
what is a unit?
A unit is a standard with which physical quantities are compared.
what are base units?
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.
what are derived units?
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.
what is scientific notation?
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
what is mantissa?
part of a number located after a decimal point.
what are prefixes?
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.
What are measuring instruments?
Measuring instruments are used to measure various physical quantities such as length, mass time etc
What is a metre rule?
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.
what is a measuring tape?
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.
prefixes in order with a power of ten.
what is a vernier caliper?
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.
What is zero error and zero correction?
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.
steps for taking reading on a scale
when is the zero error positive
when zero line of VS is on the right side of the zero of the MS
what is the zero error called when the zero of the VS is on the left side of the zero of the MS?
Negative zero error
when do we have to add or subtract measurement with zero error?
if +ve zero error subtract it from the measurement
if -ve zero error, add it with the measurement.
what does the accuracy of measuring significant figures depend on?
the quality of the measuring instrument.
the skill of the observer
the number of observations made
what are the types of value?
2 types
exact and measured
what is a significant figure?
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.
how to find the least count of the vernier caliper?
the smallest reading on the main scale/total no. of divisions on the vernier scale.
what is a stopwatch?
stopwatch is used to measure the time interval of an event. There are 2 types: mechanical and digital stopwatch.
a mechanical stopwatch can measure the time interval up to_________?
0.1 second
a digital stopwatch can measure the time interval up to_________?
0.01 second or 1/100
how to use a mechanical stopwatch?
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.
how to use a digital stopwatch?
mechanical stopwatch is also called a?
analogue stopwatch
how to measure the VOLUME of irregular shaped solid?
the meniscus of most liquids curves ________?
downwards
the meniscus of mercury curves ________?
upwards
how to use a measuring cylinder?
when the eye is above the liquid level ___________________
the meniscus appears higher than the actual height of the liquid
when the meniscus appears lower on the scale?
when the eye is below the liquid level.
what is a measuring cylinder?
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.
what is the least count of measuring cylinders?
1cm3 or 1mL
what is zero correction?
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.
what can a vernier caliper measure?
It can measure the thickness, diameter, or width of an object and the internal and external diameter of a hollow cylinder.
what can a vernier caliper measure?
It can measure the thickness, diameter, or width of an object and the internal and external diameter of a hollow cylinder.
how many scales are there in the vernier caliper?
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.
