Tag: physics

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

How many electron volts make one Joule?

  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} $
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Since 1 eV = 1.6 * 10^-19 Joules, the number of eV in 1 Joule is 1 / (1.6 * 10^-19), which equals 6.25 * 10^18.

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

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)

  1. $42^0\, C$

  2. $49^0\, C$

  3. $0.49^0\, C$

  4. $4.9^0\, C$
Reveal answer Fill a bubble to check yourself
C Correct answer
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.

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

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

  1. True

  2. False

  3. Ambiguous

  4. Data insufficient
Reveal answer Fill a bubble to check yourself
B Correct answer
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}$. 

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

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

  1. Erwin Schrodinger

  2. R.A Millikan

  3. Louis Victor de Brogue

  4. Albert Einstein
Reveal answer Fill a bubble to check yourself
C Correct answer
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.
Multiple choice physics dual nature of matter and radiation davisson and germer experiment and its conclusion matter waves wave nature of matter

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-

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

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

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

  4. $0.18\ A^{\circ}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Using Bragg's Law 2d sin(theta) = n * lambda. The wavelength lambda = sqrt(150/V) Angstroms = sqrt(150/60) = 1.58 Angstroms. Given the angle 60 degrees is to the incident beam, the glancing angle theta is 90 - 60/2 = 60 degrees (or 30 degrees depending on convention). Using standard diffraction geometry for this experiment, d = 1.8 Angstroms is the accepted value.

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

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

  1. Nickel

  2. Cobalt

  3. Iron

  4. Gold
Reveal answer Fill a bubble to check yourself
A Correct answer
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.