Tag: physics

Questions Related to physics

How many electron volts make one Joule?

physics energy and its forms introduction to work work introduction to work and energy

  1. $ 3.25 \times 10^{19} \mathrm{eV} $

  2. $ 6.25 \times 10^{18} \mathrm{eV} $

  3. $ 9.25 \times 10^{17} \mathrm{eV} $

  4. $ 1.25 \times 10^{20} \mathrm{eV} $

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Correct Option: B

Water falls from a height of $210\, m$. Assuming whole of energy due to fall is converted into heat the rise in temperature of water would be 
($J = 4.3$ Joule/cal)

physics energy and its forms introduction to work work introduction to work and energy

  1. $42^0\, C$

  2. $49^0\, C$

  3. $0.49^0\, C$

  4. $4.9^0\, C$

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Correct Option: C
Explanation:

$\begin{array}{l} \Delta \theta =0.0023h \ =0.0023\times 210 \ ={ 0.483^{ 0 } }C \ =\approx { 0.49^{ 0 } }C \end{array}$

Hence, Option $C$ is correct.

1 J Is equal to $1 : kg : m : s^{-2}$

physics energy and its forms introduction to work work introduction to work and energy

  1. True

  2. False

  3. Ambiguous

  4. Data insufficient

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Correct Option: B
Explanation:

False
because,A Joule is equal$= Newton \times meter$, and a Newton $= mass \times acceleration$The unit for mass is kg and for acceleration is m${s}^{2}$. So if a Joule $=Newton \times meter$, it equals $kgm{s}^{2}times m$. The x meter makes the meter
on top squared so you get Joules $= kg{m^2}$${s}^{-2}$. 

Which of the following will give $1J$ of work?

physics energy and its forms introduction to work work introduction to work and energy

  1. $F=1N,S=1m,\theta={0}^{0}$

  2. $F=1N,S=1m,\theta={90}^{0}$

  3. $F=0.1N,S=1m,\theta={0}^{0}$

  4. $F=0.1N,S=10m,\theta={90}^{0}$

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Correct Option: A
Explanation:

$W=F.S.cos\theta$
For $F=1, S=1, \theta={0}^{0}$, $W=1\times1{\times}cos{0}^{0}=1 J$

$4.0\times{10}^{-19}J=$

physics energy and its forms introduction to work work introduction to work and energy

  1. $1eV$

  2. $2eV$

  3. $2.5eV$

  4. $5eV$

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Correct Option: C
Explanation:

$1eV=1.6\times{10}^{-19}J$


$\therefore{4.0}\times{10}^{-19}J=\dfrac{4.0\times{10}^{-19}}{1.6\times{10}^{-19}}eV=2.5eV$

Who won the Nobel prize in physics in the year 1929 for the discovery of the wave nature of electrons?

physics dual nature of matter and radiation davisson and germer experiment and its conclusion matter waves wave nature of matter

  1. Erwin Schrodinger

  2. R.A Millikan

  3. Louis Victor de Brogue

  4. Albert Einstein

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Correct Option: C
Explanation:
The Nobel price in physics $1929$ was awarded to prince Louis Vector "for the discovery of the wave nature of electrons, as he discovered the wave nature of electrons and suggested that all the matter have wave properties.

In Davisson-Germer experiment an electron beam of energy $60\ eV$ falls normally on the surface of a crystal. If the maximum intensity is obtained at an angle of $60^{\circ}$ to the direction of incident beam. then inter-atomic distance in the lattice plane of the crystal will be-

physics dual nature of matter and radiation davisson and germer experiment and its conclusion matter waves wave nature of matter

  1. $18\ A^{\circ}$

  2. $3.6\ A^{\circ}$

  3. $1.8\ A^{\circ}$

  4. $0.18\ A^{\circ}$

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Correct Option: C

The idea of matter waves was given by

physics dual nature of matter and radiation davisson and germer experiment and its conclusion matter waves wave nature of matter

  1. Davisson and Germer

  2. de-Broglie

  3. Einstein

  4. Planck

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Correct Option: B

Drift speed of electrons is of the order of- 

physics dual nature of matter and radiation davisson and germer experiment and its conclusion matter waves wave nature of matter

  1. zero

  2. ${ 10 }^{ -2 }$ cm/sec

  3. ${ 10 }^{ 5 }$ m/sec

  4. ${ 10 }^{ -4 }$ m/sec

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Correct Option: D
Explanation:

Drift speed of electrons is of the order of ${10^{ - 4}}\,m/\sec $

Hence, the option $D$ is the correct answer.

In Davisson-Germer experiment electrons were made to strike a sheet made of ______ metal.

physics dual nature of matter and radiation davisson and germer experiment and its conclusion matter waves wave nature of matter

  1. Nickel

  2. Cobalt

  3. Iron

  4. Gold

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Correct Option: A
Explanation:

Davisson and Germer experiment was conducted by two American scientists Clinton Davisson and Lester Germer, in 1927, to verify the de Broglie hypothesis that a material particle posses wave nature. 

The electron beam was made to pass through a hole and strike the nickel crystal normally, the electrons scattered in all directions acting like waves. The detector indicated the peak intensity of scattered electrons at certain angle. This maximum intensity was due to constructive interference of two waves. Thus wave nature of electrons was experimentally proved.