Tag: physics

Questions Related to physics

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

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

  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. $\displaystyle\frac{m _e\varepsilon _0}{ce^2}$

Show answer
Correct Option: C
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.

1 kg f cm$^{-2}$ .................. Nm$^{-2}$ .

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

  1. $10^{3}$

  2. $10^{5}$

  3. $10^{4}$

  4. $10^{6}$

Show answer
Correct Option: B
Explanation:
$1kgf$ is the amount of gravitational force acting on $1kg$ of a body.
$1\ kgf\ =\ 10\ N$

And  $1m =100cm$ , 
so $1 kgf/cm^2 = 10\times10^4\ N/m^2$

we will get $10^5\ N/m^2$

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

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

  1. Energy

  2. Torque

  3. Momentum

  4. Angular momentum

Show answer
Correct Option: C
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 $Nsec$.

A Seismograph is a device that is used to measure the:

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

  1. thunderstorm

  2. earthquake

  3. lightining

  4. weather

Show answer
Correct Option: B
Explanation:

A seismograph is a device that measures and records the seismic waves moving through the earth post an earthquake.

What are seismic waves caused by?

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

  1. Volcanoes

  2. Traffic

  3. Earthquakes

  4. Heavy rain

Show answer
Correct Option: C
Explanation:

Seismic waves move through the Earth as the result of earthquakes.

The layer below the crust is called _______.
physics some natural phenomena seismic waves and tsunami causes of earthquakes origin of earth and its internal energy transfer of charge lightning safety

  1. mantle

  2. plate

  3. outer core

  4. inner core

Show answer
Correct Option: A
Explanation:

The layer below the Earth's crust is known as mantle. This consists of magma.

The Earth's crust is fragmented and each fragment is known as:

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

  1. a spot

  2. a plate

  3. a valley

  4. none of the above

Show answer
Correct Option: B
Explanation:

The Earth's crust is not a huge single piece rather it is in many pieces or fragments. The fragments are called plates.

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

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

  1. constructive

  2. destructive

  3. simple

  4. complex

Show answer
Correct Option: B
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.

Earthquakes are caused mostly due to:

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

  1. landslide

  2. flood

  3. tsunami

  4. movement of Earth's plates

Show answer
Correct Option: D
Explanation:

Due to movement of Earth's plates, most of the earthquakes occur.

Fill in the blank:

Earth's plates are in _______ motion.

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

  1. circular

  2. vibrational

  3. rotational

  4. continual

Show answer
Correct Option: D
Explanation:

Earth's plates or tectonic plates are always in motion. They continuously move and sometimes collide with each other.