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Multiple choice physics measurements and units some examples of derived units fundamental and derived quantities fundamental and derived units

Using dimensional analysis the resistivity in terms of fundamental constants $h, m _e, c, e, \varepsilon _o$ can be expressed as.

  1. $\displaystyle\frac{h}{\varepsilon _0m _ece^2}$
  2. $\displaystyle\frac{\varepsilon _0m _ece^2}{h}$
  3. $\displaystyle\frac{h^2}{m _ece^2}$
  4. $\displaystyle\frac{m _e\varepsilon _0}{ce^2}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

 SI base units of resistivity are written as $Kgm^3s^{-1}C^{-2}$.

For plank constant  $h$  SI base units are $Kgm^2s^{-1}$.
For $e$  SI unit is $C$.
For $c$  SI unit is $ms^{-1}$.
For $m _e$ SI unit is $Kg$.
For $\varepsilon _o$ SI unit is $C^2{Kg}^{-1}m^{-3}s^{2}$
Solving the dimensions of constants in option $C$,
$\dfrac{({Kgm^2s^{-1}})^2}{Kgms^{-1}C^2}=Kgm^3s^{-1}C^{-2}$
We get the dimensions of resistivity hence option $C$ is correct.

Multiple choice physics measurements and units some examples of derived units fundamental and derived quantities fundamental and derived units

Which of the following quantities has its unit as newton second?

  1. Energy

  2. Torque

  3. Momentum

  4. Angular momentum
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Dimensional formula of newton second $=\left[ \dfrac { kgm }{ { S }^{ 2 } } \times S \right] $

$=\left[ { MLT }^{ -1 } \right] $
Dimensional formula of momentum $=\left[ { MLT }^{ -1 } \right] $
Hence, momentum has the unit as $Nsec$.

Multiple choice physics some natural phenomena seismic waves and tsunami causes of earthquakes origin of earth and its internal energy transfer of charge lightning safety

Storms, cyclones, earthquake, lightning etc. are ................ natural phenomena:

  1. constructive

  2. destructive

  3. simple

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

Storms, cyclones, earthquakes and lightning are termed as natural calamities. These causes lot of damages to the properties and enviroments. Hence, they are destructive in nature.