Tag: summary of si units

Questions Related to summary of si units

The unit of absolute permitivity of a medium is 

physics measurements and units summary of si units fundamental quantities system of units

  1. Joule/Coulomb

  2. Newton-Meter

  3. Farad/Meter

  4. Farad-Coulomb

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Correct Option: C
Explanation:

Absolute permittivity $(\epsilon)$ is the measure of the resistance that  is encountered when forming an electric field in a medium. The standard SI unit for absolute permittivity is Farad per meter $(F/m)$.

The temp of the sun is measured with

physics measurements and units summary of si units fundamental quantities system of units

  1. platinum thermometer

  2. gas thermometer

  3. pyrometer

  4. vapour pressure

Show answer
Correct Option: C
Explanation:
A pyrometer is a non-contacting device that intercepts and measures thermal radiation, a process known as pyrometry. This device can be used to determine the temperature of an object's surface.  As the temperature of the sun is very high, a non-contact type temperature measurement is needed. So pyrometer will be used to measure the temperature of the sun.

One of the following dimensional quantities which one qualifies to be called dimensional constant?

physics measurements and units summary of si units fundamental quantities system of units

  1. Acceleration due to gravity

  2. surface tension of water

  3. weight of standard kilogram mass

  4. The velocity of light is vaccum

Show answer
Correct Option: D
Explanation:

Dimensonal constants are those constants while have both fixed magnitude and dimension.


$\Rightarrow $1) acceleration due gravity


$\Rightarrow $ Not a Dimensional constant because if planet changes magnitude.

Similarly the magnitude of surface tension and weight is not tired.


So  Speed of light is best if has both fixed dimension and magnitude over all universe.

Answer is speed of light.

The SI unit of electric energy or heat energy is ________.

physics measurements and units summary of si units fundamental quantities system of units

  1. joule (J)

  2. Volt (V)

  3. ampere (A)

  4. watt (W)

Show answer
Correct Option: A
Explanation:

SI unit of electric energy or heat energy is Joule (J). One Joule is defined as the amount of energy exerted when a force of one newton is applied over a displacement of one meter. One Joule is equivalent of one watt of power radiated or dissipated for one second.

The strength of force is expressed by?

physics measurements and units summary of si units fundamental quantities system of units

  1. weight

  2. mass

  3. magnitude

  4. longitudinal force

Show answer
Correct Option: C
Explanation:

The strength of a force is expressed by its magnitude. The magnitude of a force is expressed in the SI unit of force called Newton. One Newton is the force which can make an object of one kilogram mass to move at a speed of one meter per second.

The fundamental unit of the quantity of matter is :

physics measurements and units summary of si units fundamental quantities system of units

  1. kg

  2. mol

  3. gm

  4. meter

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Correct Option: B
Explanation:

Mole is standard unit to measure the amount of substance in SI system.
The mole is the amount of substance which contains as many elementary entities  present in atoms in 0.012 kg of carbon-12.

Temperature can be expressed as a derived quantity in terms of any of the following.

physics measurements and units summary of si units fundamental quantities system of units

  1. length and mass

  2. mass and time

  3. length,mass and time

  4. in terms of none

Show answer
Correct Option: D
Explanation:

Temperature is a fundamental quantity, so it can not be expressed as a derived quantity in terms of length, mass and time.So the correct option is (D).

Given  $x = a + b t + c t ^ { 2 }$  where  $x$  in metre and  $t$  in second. Find the units of $a$

physics measurements and units summary of si units fundamental quantities system of units

  1. $m s ^ { - 1 }$

  2. $m s ^ { - 2 }$

  3. $m ^ { 2 } s$

  4. $m$

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Correct Option: D

Joules / coulomb is the same as....

physics measurements and units summary of si units fundamental quantities system of units

  1. Watt

  2. ampere

  3. Volt

  4. Ohm

Show answer
Correct Option: C
Explanation:

Joule is a unit for work done and coulomb is the unit for the charge. The potential is defined as the ratio of the work done to the charge and the unit of the potential difference is volt. Hence, one joule per coulomb is equal to the unit of the potential difference. Therefore it will be equal to one Volt.

Dimension of $\sqrt { \dfrac { \epsilon _{ 0 } }{ \mu _ 0 }  }$ are

physics measurements and units summary of si units fundamental quantities system of units

  1. $[ML^2T^{-3}A^{-2}]$

  2. $[M^{-1}L^{-2}T^3A^2]$

  3. $[M^2L^2T^{-3}A^{-2}]$

  4. $[M^{-1}L^2T^3A^2]$

Show answer
Correct Option: B
Explanation:

$\sqrt{\dfrac{\varepsilon _0}{\mu _0}}=\sqrt{\dfrac{\varepsilon _0^2}{\mu _0\varepsilon _0 }}=\varepsilon _0c=[M^{-1}L^{-3}T^{4}A^2][LT^{-1}]$
$[M^{-1}L^{-2}T^{3}A^2]$