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Units and Measurement

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Physics Part I

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Physics

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CBSE Gujarat Board Haryana Board

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Class 10 Class 12

Dimensions of resistance in an electrical circuit, in terms of the dimension of mass M, of length L, of time T and of current I, would be:

  • [ML2T-3I-1]

  • [ML2T-2]

  • [ML2T-1I-1]

  • [ML2T-3I-2]


D.

[ML2T-3I-2]

Resistance 

straight R space equals space fraction numerator potential space difference over denominator current end fraction space equals space straight V over straight i space equals space straight W over qi
left parenthesis therefore space potnetial space difference space is space equal space to space work space done space per space unit space charge right parenthesis
equals space fraction numerator left square bracket Dimensions space of space work right square bracket over denominator left square bracket Dimensions space of space charge right square bracket left square bracket Dimensions space of space current right square bracket end fraction
space equals space fraction numerator left square bracket ML squared straight T to the power of negative 2 end exponent right square bracket over denominator left square bracket IT right square bracket left square bracket straight I right square bracket end fraction space equals space left square bracket ML squared straight T to the power of negative 3 end exponent straight I to the power of negative 2 end exponent right square bracket

Resistance 

straight R space equals space fraction numerator potential space difference over denominator current end fraction space equals space straight V over straight i space equals space straight W over qi
left parenthesis therefore space potnetial space difference space is space equal space to space work space done space per space unit space charge right parenthesis
equals space fraction numerator left square bracket Dimensions space of space work right square bracket over denominator left square bracket Dimensions space of space charge right square bracket left square bracket Dimensions space of space current right square bracket end fraction
space equals space fraction numerator left square bracket ML squared straight T to the power of negative 2 end exponent right square bracket over denominator left square bracket IT right square bracket left square bracket straight I right square bracket end fraction space equals space left square bracket ML squared straight T to the power of negative 3 end exponent straight I to the power of negative 2 end exponent right square bracket

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Give four examples of physical quantities.

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

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.


878 Views

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. 
825 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. 
1289 Views

Define unit.

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

Example: Unit of time is second. 

1172 Views