Tag: physics

Questions Related to physics

Renewable source of energy is 

physics sources of energy wave energy tidal energy wave power and tidal power

  1. Coal

  2. Petrolium

  3. Natural gas

  4. Energy of flowing water

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Correct Option: D
Explanation:

Energy of flowing water

At many places in the ocean, the different in temperatures between the water 'at the surface of ocean' and 'at deeper levels' is up to

physics sources of energy wave energy tidal energy wave power and tidal power

  1. $120^0C$

  2. $80^0C$

  3. $50^0C$

  4. $20^0C$

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Correct Option: D

Arrange the following steps of conversion of ocean thermal energy into electricity, in a proper sequence.
(a) The vapour of ammonia or CFC is passed over the turbines of generators.
(b) The hot water from the ocean is used to vapourise the liquid like ammonia or CFC.
(c) Cold water from the ocean depths is used to cool the vapour again into liquid.
(d) This cold liquid is again vapourised and the process continues.

physics sources of energy wave energy tidal energy wave power and tidal power

  1. b a c d

  2. c a b d

  3. c b a d

  4. a b c d

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Correct Option: A
Explanation:

The hot water in the ocean is used to evaporate liquids like ammonia or CFC. This vapour is used to rotate the turbines of the generator and the vapour is again cooled down to a liquid by using the cold water from the ocean depth. This cooled liquid ammonia or CFC is again vapourised and the above process continues.

Tidal energy is a major source of energy due to the presence of large water bodies on the earth.

physics sources of energy wave energy tidal energy wave power and tidal power

  1. True

  2. False

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Correct Option: B

_________ are used to produce energy in OTEC.

physics sources of energy wave energy tidal energy wave power and tidal power

  1. Tidal energy

  2. Temperature difference between the different layers of water in ocean

  3. Ocean waves

  4. None of the above

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Correct Option: B

Which of the following is not a form of oceanic energy?

physics sources of energy wave energy tidal energy wave power and tidal power

  1. Energy from biomass

  2. Tidal energy

  3. Ocean thermal energy

  4. Solar energy

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Correct Option: D

Energy available from the oceans is

physics sources of energy wave energy tidal energy wave power and tidal power

  1. OTE

  2. Tidal energy

  3. Sea-waves energy

  4. All of these

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Correct Option: D

The oceans cover almost ...... percent of the surface of earth with water and act as a vast collector of ...... energy.

physics sources of energy wave energy tidal energy wave power and tidal power

  1. $71$, chemical

  2. $97$, solar

  3. $71$, solar

  4. $17$, hydroenergy

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Correct Option: C

In Bohr's atom the number of de Broglie's waves associated with an electron moving in $n^{th}$ permitted orbit is:-

limitations of bohr model and explanation of bohr's second postulate by matter waves bohr's model atoms atomic nuclei physics

  1. $n$

  2. $2n$

  3. $\dfrac{n}{2}$

  4. $n^2$

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Correct Option: A
Explanation:
According to Bohr's postulate and de-Broglie the relation for $n^{th}$ orbit is like this $2\pi r _n=n\lambda$
Where $r _n$ is radius of $n^{th}$ orbit and $\lambda$ is deBroglie wavelength of electron in that orbit.
So number of de-Broglie wavelength is $n$.
Correct option is A.

Wavelength of first line in Lyman series is $\lambda $. The wavelength of first line in Balmer series is:

limitations of bohr model and explanation of bohr's second postulate by matter waves bohr's model atoms atomic nuclei physics

  1. $\dfrac { 5 }{ 27 } \lambda $

  2. $\dfrac { 32}{ 27 } \lambda $

  3. $\dfrac { 27 }{ 5 } \lambda $

  4. $\dfrac { 27 }{ 32 } \lambda $

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Correct Option: C
Explanation:

According to Bohr, the wavelength emitted when an electron jumps from ${ n } _{ 1 }^{ th }$ to ${ n } _{ 2 }^{ th }$ orbit is
$E=\dfrac { hc }{ \lambda  } ={ E } _{ 2 }-{ E } _{ 1 }$
$\Rightarrow \dfrac { 1 }{ \lambda  } =R\left( \dfrac { 1 }{ { n } _{ 1 }^{ 2 } } -\dfrac { 1 }{ { n } _{ 2 }^{ 2 } }  \right) $
For first line in Lyman series
$\dfrac { 1 }{ { \lambda  } _{ L } } =R\left( \dfrac { 1 }{ { 1 }^{ 2 } } -\dfrac { 1 }{ { 2 }^{ 2 } }  \right) =\dfrac { 3R }{ 4 } $                        ......(i)
For first line in Balmer series,
$\dfrac { 1 }{ { \lambda  } _{ B } } =R\left( \dfrac { 1 }{ { 2 }^{ 2 } } -\dfrac { 1 }{ { 3 }^{ 2 } }  \right) =\dfrac { 5R }{ 36 } $                      ......(ii)
From equations (i) and (ii)
$\therefore \dfrac { { \lambda  } _{ B } }{ { \lambda  } _{ L } } =\dfrac { 3R }{ 4 } \times \dfrac { 36 }{ 5R } =\dfrac { 27 }{ 5 } $
$\therefore { \lambda  } _{ B }=\dfrac { 27 }{ 5 } \lambda $               $\left( \because { \lambda  } _{ L }=\lambda  \right) $