Tag: measurements and units

Questions Related to measurements and units

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

Which of the following pairs is not matched?

physics measurements and units kinds of units fundamental quantities standardized measurement

  1. Coefficient of self-induction : henry

  2. Magnetic flux : weber

  3. Electric flux : volt-meter

  4. Electric capacity : farad-meter

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Correct Option: D
Explanation:

Electric capacitance of a conductor is the ability with which the conductor can hold the charge.
In SI system, unit of capacitance is farad($F$).
Hence, option D is not matched.

kilowatt-hour is the unit of ____. 

physics measurements and units kinds of units fundamental quantities standardized measurement

  1. potential difference

  2. electric power

  3. electric energy

  4. charge

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Correct Option: C
Explanation:

$\text{Kilowatt hour}$ is the $commercial$ unit of $electrical$ ENERGY.

As the power$(means $ $ \dfrac{Work}{time}=\dfrac{energy}{time})$
so $energy=power\times time $

$\text{so unit of energy= unit of power *unit of time =watt *second }$
Kilowatt-hour is just $3600\times 1000$ times  of the above value of energy.

Oersted is the unit of

physics measurements and units kinds of units fundamental quantities standardized measurement

  1. Intensity of magnetisation

  2. Magnetic moment

  3. Magnetic induction

  4. Magnetic flux

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Correct Option: A
Explanation:

The intensity of magnetic field at a point on the field is defined as the force on a unit north pole placed at that point.
Intensity of magnetization is measured in Oersted as a unit.

The SI unit of pressure is

physics measurements and units kinds of units fundamental quantities standardized measurement

  1. $Newton$

  2. $Joule$

  3. $N/m^{2}$

  4. $Nm$

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Correct Option: C
Explanation:

Pressure is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. It is defines as force per unit area. The SI unit of pressure is $N/m^2$.

The damping force on an oscillator is directly proportional to the velocity. The units of constant of proportionality are

physics measurements and units kinds of units fundamental quantities standardized measurement

  1. Kg m/s

  2. Kg $m/s^2$

  3. Kg/s

  4. kgs

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Correct Option: C