Tag: physics

Questions Related to physics

The prefix used to represent $\displaystyle { 10 }^{ -2 }$ is called

physics dynamics - explaining motion summary of si units fundamental quantities system of units

  1. Milli

  2. Centi

  3. Kilo

  4. Deci

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Correct Option: B
Explanation:

The prefix used to represent $10^{-2}$ is called Centi.

1 nano metre (1 nm) is equal to

physics dynamics - explaining motion summary of si units fundamental quantities system of units

  1. $\displaystyle { 10 }^{ -7 }$m

  2. $\displaystyle { 10 }^{ -9 }$m

  3. $\displaystyle { 10 }^{ 9 }$m

  4. None of these

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Correct Option: B
Explanation:
Nano meter is a very small unit of length.
$1 \ nm = 10^{-9}\  m$

SI unit of energy is joule .

physics dynamics - explaining motion summary of si units fundamental quantities system of units

  1. True

  2. False

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Correct Option: A
Explanation:

Joule $(J)$ is the SI unit of energy. So, the given statement is true.

The dimensional formula for magnetic flux is:

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

  1. $(ML^2T^{-2}A^{-1})$

  2. $(ML^3T^{-2}A^{-2})$

  3. $(M^0L^{-2}T^{2}A^{-2})$

  4. $(ML^2T^{-1}A^{2})$

Show answer
Correct Option: A
Explanation:

The magnetic flux if given by

$\phi=BAcos\theta$
If $cos\theta=1$
The maximum magnetic flux, $\phi=BA$. . . . . .(1)
where, $B=$ magnetic field
$A=area$ 
The dimensional formula for magnetic field,
$F=qvB$
where, $v=$ velocity
$q=$ charge,
$B=$ magnetic field
$[B]=\dfrac{M^1 L^1T^{-2}}{[A^1 T^1][L^1T^{-1}]}$
$[B]=[M^1L^0T^{-2}A^{-1}]$
for area, $[A]=[M^0 L^2 T^0]$
The dimensional formula for magnetic flux,
$[\phi]=[M^1L^0 T^{-2}A^{-1}].[M^0L^2T^0]$
$[\phi]=[M^1L^2T^{-2}A^{-1}]$
The correct option is A.

The SI unit of gravitational potential is :

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

  1. Joule/kg

  2. Joule$^2$/kg

  3. kg/Joule

  4. Joule/kg$^2 $

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Correct Option: A
Explanation:

The gravitational potential at a point is the potential energy associated with a unit mass due to its position in the gravitational field of another body. Gravitational potential is the amount of work done in bringing a body of unit mass from infinity to that point.
Gravitational potential (V) $=\dfrac{Work done}{Mass}=\dfrac{W}{m}$
Gravitational potential  is a scalar quantity and the  SI unit is $J/kg$. 

Siemen is the SI unit of

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

  1. resistivity

  2. resistance

  3. conductivity

  4. conductance

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Correct Option: D
Explanation:

Conductance, $G=\dfrac {1}{resistance}=mho(\Omega^{-1})$ or Siemens (S)


Unit for conductivity is $\mu S/cm$

Which of the following unit is not a fundamental unit:

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

  1. Meter

  2. Litre

  3. Second

  4. Kilogram

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Correct Option: B
Explanation:

Litre is not a fundamental unit.

The SI unit of $ \dfrac{1}{2 \pi \sqrt{LC}}$ is equivalent to that of :

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

  1. time period

  2. frequency

  3. wavelength

  4. wave number

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Correct Option: B
Explanation:

The angular frequency of current oscillations in an LC circuit is given by $\omega =\dfrac{1}{\sqrt {LC}}$ and $\omega = 2\pi f$.
$\Rightarrow f= \dfrac{1}{2\pi \sqrt{LC}}$ and the unit is equivalent to that of frequency.

The SI unit of coefficient of mutual inductance of a coil is

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

  1. henry

  2. volt

  3. farad

  4. weber

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Correct Option: A
Explanation:

The henry (symbolized H) is the Standard International ( SI ) unit of coefficient of mutual inductance of a coil .

The S.I. unit of pole strength is

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

  1. $Am^2$

  2. $Am$

  3. $Am^{-1}$

  4. $Am^{-2}$

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Correct Option: B
Explanation:

Pole strength, $m=\displaystyle \frac {Magnetic \ moment}{2l}=\frac {Am^2}{m}=Am$