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Multiple choice physics measurements and units kinds of units fundamental quantities standardized measurement

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

  1. $N s {m}^{2} radian $
  2. $Ns/m/Radian$
  3. $Radian/Ns/m$
  4. $ Ns/m/Radian^2 $
Reveal answer Fill a bubble to check yourself
A Correct answer
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 $=radian \times$ $N\, s\, { m }^{ -2 }\times { m }^{ 4 }=N\,s \, { m }^{ 2 } \ radian$

Multiple choice physics measurements and units kinds of units fundamental quantities standardized measurement

Unit of self inductance is

  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 } $
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Self inductance L has the SI unit Henry (H), which equals volt-second/ampere. From V = L(dI/dt), dimensionally [H] = [V][T]/[A]. Option B: joule×second/(coulomb×ampere) = (V×C×T)/(C×A) = V×T/A = Henry, which is correct. Note that 'coubmb' in option B appears to be a typo for coulomb.

Multiple choice physics measurements and units kinds of units fundamental quantities standardized measurement

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

  1. Speed

  2. Current

  3. Charge

  4. Potential difference
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The term epsilon_0 * (d_phi / dt) is the displacement current in Maxwell's equations, which has the same dimensions as electric current.

Multiple choice physics measurements and units kinds of units fundamental quantities standardized measurement

Which of the following pairs is not matched?

  1. Coefficient of self-induction : henry

  2. Magnetic flux : weber

  3. Electric flux : volt-meter

  4. Electric capacity : farad-meter
Reveal answer Fill a bubble to check yourself
D Correct answer
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.

Multiple choice physics measurements and units kinds of units fundamental quantities standardized measurement

kilowatt-hour is the unit of ____. 

  1. potential difference

  2. electric power

  3. electric energy

  4. charge
Reveal answer Fill a bubble to check yourself
C Correct answer
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.