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Class 10 Class 12

In an experiment, four quantities a,b, c and d are measured with percentage error 1%, 2%, 3% and 4% respectively. Quantity P is calculated as follows:
P = fraction numerator straight a cubed straight b squared over denominator cd end fraction space percent sign, error in P is

  • 14 %

  • 10 %

  • 7 %

  • 4 %


A.

14 %

Here, P = fraction numerator straight a cubed straight b squared over denominator cd end fraction
Therefore,

fraction numerator increment straight P over denominator straight P end fraction space x space 100
open parentheses fraction numerator 3 increment straight a over denominator straight a end fraction plus fraction numerator 2 increment b over denominator b end fraction plus fraction numerator increment c over denominator c end fraction plus fraction numerator increment d over denominator d end fraction close parentheses x 100
3 fraction numerator increment straight a over denominator straight a end fraction straight x 100 space plus space 2 space fraction numerator increment straight b over denominator straight b end fraction straight x 100 space plus space fraction numerator increment straight c over denominator straight c end fraction straight x 100 space plus space fraction numerator increment straight d over denominator straight d end fraction straight x 100
= 3 x1 + 2 x 2 + 3 +4 

= 3 + 4 + 3 + 4

= 14 %

Here, P = fraction numerator straight a cubed straight b squared over denominator cd end fraction
Therefore,

fraction numerator increment straight P over denominator straight P end fraction space x space 100
open parentheses fraction numerator 3 increment straight a over denominator straight a end fraction plus fraction numerator 2 increment b over denominator b end fraction plus fraction numerator increment c over denominator c end fraction plus fraction numerator increment d over denominator d end fraction close parentheses x 100
3 fraction numerator increment straight a over denominator straight a end fraction straight x 100 space plus space 2 space fraction numerator increment straight b over denominator straight b end fraction straight x 100 space plus space fraction numerator increment straight c over denominator straight c end fraction straight x 100 space plus space fraction numerator increment straight d over denominator straight d end fraction straight x 100
= 3 x1 + 2 x 2 + 3 +4 

= 3 + 4 + 3 + 4

= 14 %

3312 Views

What is measurement?

Measurement is the process of attaching a numeric value to an aspect of a natural phenomenon. Measurement is making the quantitative knowledge of a physical quantity. 
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What is the need of measurement?

To get the complete knowledge of any physical quantity, measurement is needed. Measurement of any physical quantity involves comparison with a certain basic, arbitrarily chosen, internationally accepted reference standard called unit. Knowledge without measurement is incomplete and unsatisfactory. 
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Define physical quantity.

 


A measurable quantity in terms of which laws of Physics can be expressed is called physical quantity.

The result of a measurement of a physical quantity is expressed by a number accompanied by a unit.


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Define unit.

The quantity used as a standard of measurement is called unit. 

Example: Unit of time is second. 

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Give four examples of physical quantities.

Examples of Physical quantitie are force, mass, density and power.
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