Tag: standardized measurement

Questions Related to standardized measurement

Among the following indentify the derived quantities.

physics measurement of physical quantities kinds of units fundamental quantities standardized measurement

  1. Gravitational constant

  2. Frequency

  3. Electric charge

  4. Electric current

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Correct Option: A,B,C
Explanation:

The derived quantities are gravitational constant, frequency, electric charge because they are made up of several other quantities combined to form one single quantity.

The energy which an electron acquires when accelerated, through a potential difference of $1$ volt is called

physics measurements and units kinds of units fundamental quantities standardized measurement

  1. $1$ Joule

  2. $1$ eV

  3. $1$ erg

  4. $1$ watt

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Correct Option: B
Explanation:

The energy which an electron acquires when accelerated, through a potential difference of 11 volt is called 1 eV. It is a unit of energy.  It is usually used as a measure of particle energies although it is not an SI (System International) unit. The SI unit for energy is the Joule. $1\,eV=1.602\times 10^{-19}\,Joules$

The Sl unit of length is the meter. Suppose we adopt a new unit of length which equals to $x$ meters. The area 1 $m ^ { 2 }$ expressed in terms of the new unit has a magnitude:

physics measurements and units kinds of units fundamental quantities standardized measurement

  1. $x$

  2. $x ^ { 2 }$

  3. $\dfrac { 1 } { x }$

  4. $\dfrac { 1 } { x ^ { 2 } }$

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Correct Option: D
Explanation:

SI unit of Length $=$ meters.

New Unit of Length $=x$ meters.

$1m=\dfrac 1x$ new units

SI unit of area : 

$A= 1m^2$   

$=1\times 1m^2$                        

$=\dfrac 1x\times \dfrac 1x $     

$=\dfrac{1}{x^2}$     

The impulse $J$ required to bring it to rest when it reaches the vertical position.

physics measurement of physical quantities kinds of units fundamental quantities standardized measurement

  1. Impulse of $m\sqrt {\dfrac {gl}{3}}$ when it is applied horizontally at distance $l$ from pivoted point

  2. Impulse of $m\sqrt {\dfrac {gl}{3}}$ when it is applied horizontally at distance $\dfrac {l}{2}$ from pivoted point

  3. Minimum impulse is $m\sqrt {\dfrac {gl}{2}}$ when it is applied at distance $l$ from pivoted point

  4. If rod is stopped by applying minimum impulse then the is impulse imparted by pivot is $\dfrac {m\sqrt {gl}}{2\sqrt {3}}$

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Correct Option: A

If $10 ^ { 7 }$ era is taken as unit of energy, $10 ^ { 5 }$ dyne as the unit of force, one second as unit of time. what is, the unit of length?

physics measurements and units kinds of units fundamental quantities standardized measurement

  1. $1$ $m$

  2. $10$ $m$

  3. $100$ $m$

  4. None

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Correct Option: A

The following quantities which have same directions :

physics measurements and units kinds of units fundamental quantities standardized measurement

  1. force, impulse

  2. impulse, change in momentum

  3. change in velocity, change in momentum

  4. All the above

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Correct Option: A

The MKS unit of quantity $\dfrac{\pi \eta r^4}{2}$ is :

physics measurements and units kinds of units fundamental quantities standardized measurement

  1. $N s {m}^{2} radian  $

  2. $Ns/m/Radian$

  3. $Radian/Ns/m$

  4. $ Ns/m/Radian^2 $

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Correct Option: A
Explanation:

Unit of $\pi $ is radians.

Unit of $r$ is $m$.
Unit of coefficient of viscosity, $\eta =N\, s\, { m }^{ -2 } $
Whereas $2$ is just a number, so it is unit less.
Therefore, Unit of given expression $=radian \times$ $N\, s\, { m }^{ -2 }\times { m }^{ 4 }=N\,s \, { m }^{ 2 } \ radian$

In S.l. system the value of $\epsilon _ { 0 }$

physics measurements and units kinds of units fundamental quantities standardized measurement

  1. $1 c ^ { 2 } N ^ { - 1 } m ^ { - 2 }$

  2. $9 \times 10 ^ { 9 } c ^ { 2 } N ^ { - 1 } m ^ { - 2 }$

  3. $\cfrac { 1 } { 9 \times 10 ^ { 9 } } c ^ { 2 } N ^ { - 1 } m ^ { - 2 }$

  4. $\cfrac { 1 } { 4 \pi \times 9 \times 10 ^ { 9 } } c ^ { 2 } N ^ { - 1 } m ^ { - 2 }$

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Correct Option: D

Unit of self inductance is

physics measurements and units kinds of units fundamental quantities standardized measurement

  1. $\cfrac { newton\ second }{ coulomb\quad \times \quad ampere } $

  2. $\cfrac { joule/coubmb\quad \times \quad second }{ ampere } $

  3. $\cfrac { volt\quad \times \quad metre }{ coulomb } $

  4. $\cfrac { newton\quad \times \quad metre }{ ampere } $

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Correct Option: B

If $\epsilon ,\phi $ and  t stand for permittivity,electric flux and time respectively, then dimensions of $ \epsilon \cfrac{d \phi}{dt}$ is same as that

physics measurements and units kinds of units fundamental quantities standardized measurement

  1. Speed

  2. Current

  3. Charge

  4. Potential difference

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Correct Option: B