Tag: physics

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Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

Which row describes the nature of $\alpha$- particles and of $\gamma$- rays

  1. $\alpha$- particles : helium nuclei ; $\gamma$ rays - electromagnetic radiation

  2. $\alpha$- particles : helium nuclei ; $\gamma$ rays - electrons

  3. $\alpha$- particles : protons; $\gamma$ rays - electromagnetic radiation

  4. $\alpha$- particles : protons; $\gamma$ rays - electrons
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Characteristics of $\alpha$ particle
  mass= $4$ unit
  charge = $+2$ unit
The mass of Helium nuclei is $4$ unit and charge is $+2$ unit. So, it is equivalent to $\alpha $ particle .

$\gamma $- rays  is a penetrating electromagnetic radiation arising from the radioactive decay of atomic nuclei.
Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

A scientist carries out an experiment using a sealed source which emits $\beta$ -particles. The range of the $\beta$- particles in the air is about $30cm$.
Which precaution is the most effective to protect the scientist from the radiation?

  1. handling the source with long tongs

  2. keeping the temperature of the source low

  3. opening all windows in the laboratory

  4. washing his hands before leaving the laboratory
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Handling the source with long tongs will prevent him from the exposure of $\beta$- particles. Since the range of $\beta$-particle is only $30cm$ so, long tongs can easily be a safer and effective precaution.

Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

One electron volt is equal to .......................

  1. $\displaystyle 1.6\times 10^{-19}$ Joule

  2. $\displaystyle 16\times 10^{-19}$ Joule

  3. $\displaystyle 1.6\times 10^{-10}$ Joule

  4. $\displaystyle 1.6\times 10^{-9}$ Joule
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

One electron volt is the energy gained by an electron accelerated through a potential difference of 1 volt, which is 1.6 * 10^-19 Joules.

Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

How much energy is released when a $ _{8}{O}^{16}$ nucleus is completely converted into energy?

The binding energy per nucleon of $ _{8}{O}^{16}$ is $7.97  MeV$ and ${m} _{p} = 1.0078  u$ and ${m} _{n} = 1.0087  u$

  1. $14899.438 MeV$

  2. $148.99 MeV$

  3. $4489.73 MeV$

  4. $448.973 MeV$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Binding Energy $=E=\triangle mc^2$
$\triangle m=$ mass of nucleus $-$ (mass of proton + neutron)
Multiplying both sides by $c^2$
$\triangle mc^2=$ (mass of nucleus)$c^2 -$ (mass of proton + neutron)$c^2$
$=7.97\times 16-8(1.0078+1.0087)931 \\ E=127.52-15018.892 \\ E=-14899.438MeV$
Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

What is the energy required to increase the mass of a system by one atomic mass unit?

  1. 661.5 MeV

  2. <span>931.5 MeV</span>

  3. <span>1336.5 MeV</span>

  4. <span>785.2 MeV</span>
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$\Delta m = 1  u$
$E = 1 \times 931.5  MeV = 931.5  MeV$

Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

Using $E = m{c}^{2}$, find out the energy released, when $2  u$ of mass is destroyed completely.
Take $1  u = 1.66 \times {10}^{-27}  kg$.

  1. $4.65 MeV$

  2. $3627 MeV$

  3. $91.5 MeV$

  4. $1865 MeV$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
When $2u$ of mass is destroyed completely then
$\triangle m=2u\\ E=\triangle m{ c }^{ 2 }\\ E=2\times 931MeV\\ \therefore 1u=931Mev/{ c }^{ 2 }\\ So,E=1863MeV\approx 1865MeV$
So, (D) is correct option.
Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics
What  describe the Einsteins equation for the relativity of mass and energy ?

  1. a small amount of mass contains a lot of energy.

  2. a small amount of energy can be converted into a large amount of mass.

  3. a small amount of mass contains a small amount of energy.

  4. mass can be converted into energy, but energy cannot be converted mass.

  5. energy can be converted into mass, but mass cannot be converted into energy.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Sir Einstein's mass-energy equation states that mass and energy can be converted into each other by the following relation.

                 $E=mc^{2}$,    ($c=$speed of light)
This implies that a small amount of mass contains a lot of energy, which can be proved with an example.
Let we have a mass of $1g=10^{-3}kg$ , therefore energy produced by it will be:
                      $E=10^{-3}\times \left(3\times10^{8}\right)^{2}=9\times10^{13}J$ 
which is a vast amount energy produced by only one gram (small mass) of mass.
Whereas a small amount of energy doesn't give a large amount of mass because for that we have to divide the energy by $c^{2}$, which gives a small mass.