Tag: measurements and units

Quizzes (10) Questions (257)

Questions Related to measurements and units

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

Column I gives three physical quantities. Select the appropriate units for these from the choices given in column II. Some of the physical quantities may have more than one choice.

Column-I Column - II
a) Capacitance d) Ohm second
b) Inductance e) Coulomb$^{2}$ joule$^{ -1 }$
c) Magnetic induction f) Coulomb volt$^{ -1 }$
g) Newton (ampere/metre)$^{ -1 }$
h) Volt second (ampere)$^{ -1 }$

  1. a-e,f; b-d,h; c-g

  2. a-h; b-d; c-e

  3. a-e; b-g,h; c-g

  4. a-e,f; b-d,h; c-d,e
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Capacitance is charge per unit volt. 

Volt has unit of work per unit chage. 
So capacitance has units of charge square per unit energy. 
Inductance is defined as volt per unit rate of change of current and voltage per unit current is resistance, so inductance is ohm second. 

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

The SI unit of magnetic permeability is

  1. ${ Am }^{ -1 }$
  2. ${ Am }^{ -2 }$
  3. ${ Hm }^{ -2 }$
  4. ${ Hm }^{ -1 }$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The correct option is D.

The magnetic permeability of any material is its property for allowing the magnetic line of force to pass through it. Therefore, the magnetic material can support the development of the magnetic field. This capability is measured by the magnetic permeability. Also, the magnetic line of force is directly proportional to the conductivity of the material. Its SI unit is Henry per meter i.e. $Hm^{-1}$ or newton per ampere square.

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

$\left( Coulomb \right) ^{ 2 }{ J }^{ -1 }$ can be the unit of :

  1. electric resistence

  2. electric energy

  3. electric capacity

  4. electric power
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Electric energy $=ML^{2}T^{-2}$
Electric power $=ML^{2}T^{-3}$
Electric resistance $= ML^{2}I^{-2}T^{-3}$
Electric capacity $=M^{-1}L^{-2}I^{2}T^{4}$$=\left ( \dfrac{I^{2}T^{2}}{(M^{1}L^{2}T^{-2})} \right )=\left ( \dfrac{Q^{2}}{J} \right )$
Hence, option C is correct.

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

The energy which an electron acquires when accelerated, through a potential difference of $1$ volt is called

  1. $1$ Joule
  2. $1$ eV
  3. $1$ erg
  4. $1$ watt
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The energy which an electron acquires when accelerated, through a potential difference of 11 volt is called 1 eV. It is a unit of energy.  It is usually used as a measure of particle energies although it is not an SI (System International) unit. The SI unit for energy is the Joule. $1\,eV=1.602\times 10^{-19}\,Joules$

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

The Sl unit of length is the meter. Suppose we adopt a new unit of length which equals to $x$ meters. The area 1 $m ^ { 2 }$ expressed in terms of the new unit has a magnitude:

  1. $x$
  2. $x ^ { 2 }$
  3. $\dfrac { 1 } { x }$
  4. $\dfrac { 1 } { x ^ { 2 } }$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

SI unit of Length $=$ meters.

New Unit of Length $=x$ meters.

$1m=\dfrac 1x$ new units

SI unit of area : 

$A= 1m^2$   

$=1\times 1m^2$                        

$=\dfrac 1x\times \dfrac 1x $     

$=\dfrac{1}{x^2}$     

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

If $10 ^ { 7 }$ era is taken as unit of energy, $10 ^ { 5 }$ dyne as the unit of force, one second as unit of time. what is, the unit of length?

  1. $1$ $m$
  2. $10$ $m$
  3. $100$ $m$

  4. None
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Energy E = M L^2 T^-2 = 10^7 erg = 1 Joule. Force F = M L T^-2 = 10^5 dyne = 1 Newton. Time T = 1 second. Using F = M L T^-2 and E = F L, we get 1 Joule = 1 Newton * L, so L = 1 meter.