Tag: physics

Questions Related to physics

Relation between pressure ($P$) and energy density ($E$) of an ideal gas is-

physics behaviour of perfect gas and kinetic theory of gases degree of freedom: law of equipartition of energy law of equipartition of energy law of equipartition of energy and mean free path

  1. $P=2/3E$

  2. $P=3/2E$

  3. $P=3/5E$

  4. $P=E$

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Correct Option: A
Explanation:
Kinetic energy $=\dfrac{1}{2}{ MV } _{ rms }$
$\Rightarrow \dfrac{1}{2}M\left( \dfrac { 3RT }{ M }  \right) $        $[M=$ molar mass,$ { V } _{ rms }=\sqrt { \dfrac { 3KT }{ { m } }  } =\sqrt { \dfrac { 3RT }{ M }  } ]$
$=\dfrac{3}{2}RT$
$\Rightarrow K.E=\dfrac{3}{2}PV$          $[PV=RT]$
$\Rightarrow \dfrac{K.E}{V}=\dfrac{3}{2}P$
$\Rightarrow E=\dfrac{3P}{2}$        $E=$ Energy density.
Hence, the answer is $P=\dfrac{2}{3}E.$

A vessel of volume $0.3 \ { { m }^{ 3 } }$ contains Helium at $20.0$. The average kinetic energy per molecule for the gas is:

physics behaviour of perfect gas and kinetic theory of gases degree of freedom: law of equipartition of energy law of equipartition of energy law of equipartition of energy and mean free path

  1. $6.07\times { 10 }^{ -21 }J$

  2. $7.3\times { 10 }^{ 3 }J$

  3. $14.6\times { 10 }^{ 3 }J$

  4. $12.14\times { 10 }^{ -21 }J$

Show answer
Correct Option: A
Explanation:
Given temperature of gas $=20°C$
                                            $=293K$
$\Rightarrow$ Average translational kinetic energy $=\dfrac{3}{2}KT$
                                                                   $=\dfrac{3}{2}\times1.38\times10^{-23}\times293$
                                                                   $=6.07\times10^{-21}J$
Hence, the answer is $6.07\times10^{-21}J.$

Light pollution is caused when

physics science in daily life inventions and inventors in science scientists indian scientist: biography and achievements

  1. the ozone layer is damaged

  2. too much of light sources are used unnecessarily

  3. light sources pointing up to the sky rather than down to the earth

  4. sources of light are polluted

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Correct Option: C

The volume of a single liquid drop can be measured using a :

physics science in daily life inventions and inventors in science scientists indian scientist: biography and achievements

  1. measuring jar

  2. measuring flask

  3. pipette

  4. burette

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Correct Option: D

Which of the following is not the contribution of Sir Issac Newton?

physics science in daily life inventions and inventors in science scientists indian scientist: biography and achievements

  1. Universal Law of Gravitation

  2. Laws of Motion

  3. Ultra Short Radio Waves

  4. Reflecting Telescope

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Correct Option: C
Explanation:

Sir J. C. Bose discovered Ultra Short Radio Waves.

Which of the following scientists is known for his outstanding work in the genetic code?

physics science in daily life inventions and inventors in science scientists indian scientist: biography and achievements

  1. Satyendra Nath Bose

  2. Vikram Sarabhai

  3. Srinivasa Ramanujan

  4. Har Gobind Khorana

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Correct Option: D

Which Indian scientist is known for his crucial role in the development of Indias missile and nuclear weapons programmes?

physics science in daily life inventions and inventors in science scientists indian scientist: biography and achievements

  1. A. P. J. Abdul Kalam

  2. C. V. Raman

  3. Jagadish Chandra Bose

  4. Har Gobind Khorana

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Correct Option: A
Explanation:

A.P.J Abdul Kalam aka Missile Man, is known for hi crucial role in development of Indian missiles and nuclear weapons programmes.

......... suggested that the slips should be marked with load lines

physics electric current and its effects electric fuse electrical fuse and mcb fuse

  1. Samuel Plimsoll

  2. Einstein

  3. Newton

  4. Archimedes

Show answer
Correct Option: C
Explanation:

Fuse should be connected to live / phase wire o fthe circuit. If it is connected to neutral wire , the fuse will melt when excess current flows, but the appliance will still be connected to high potential through live wire. Thus, if a person touches the appliance, he receives shock. 
Hence, choice is (3) 

Fill in the blank-
An electric fuse works on the ______effect of current.

physics electric current and its effects electric fuse electrical fuse and mcb fuse

  1. heating

  2. magnetic

  3. chemical

  4. none of these

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Correct Option: A
Explanation:

Electric fuse work on the principal of heating effect of current . fuse wire is a wire of high resistance and low melting point. when very large current will pass through it, heat will be generated which will melt the fuse wire and break the circuit.By using electric fuses in home we can protect the home appliances from damaging by large amount of current.

A fuse wire is generally made of

physics electric current and its effects electric fuse electrical fuse and mcb fuse

  1. tin

  2. tin-lead alloy

  3. copper

  4. either (a) or (b) above

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Correct Option: D
Explanation:

Fuse wire are used to save the home appliances from damagaing by large currents. so they are made up of such materials which have high resistance and low melting point so that they can melt down when unexpected amount of current is passed through.for this work either tin metal or tin-lead alloy will be appropriate.