Tag: summary of si units

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

The unit of absolute permitivity of a medium is 

  1. Joule/Coulomb

  2. Newton-Meter

  3. Farad/Meter

  4. Farad-Coulomb
Reveal answer Fill a bubble to check yourself
C Correct answer
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 $(F/m)$.

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

The temp of the sun is measured with

  1. platinum thermometer

  2. gas thermometer

  3. pyrometer

  4. vapour pressure
Reveal answer Fill a bubble to check yourself
C Correct answer
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.
Multiple choice physics measurements and units summary of si units fundamental quantities system of units

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

  1. Acceleration due to gravity

  2. surface tension of water

  3. weight of standard kilogram mass

  4. The velocity of light is vaccum
Reveal answer Fill a bubble to check yourself
D Correct answer
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.

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

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

  1. joule (J)

  2. Volt (V)

  3. ampere (A)

  4. watt (W)
Reveal answer Fill a bubble to check yourself
A Correct answer
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.

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

The strength of force is expressed by?

  1. weight

  2. mass

  3. magnitude

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

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

Joules / coulomb is the same as....

  1. Watt

  2. ampere

  3. Volt

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

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

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

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

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

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

  4. $[M^{-1}L^2T^3A^2]$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

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