Tag: physics

Quizzes (598) Questions (13441)

Questions Related to physics

Multiple choice physics electric current and circuit domestic electric circuits and safety precautions domestic and commercial circuit electric power

The wire having a black plastic covering is a

  1. live wire

  2. neutral wire

  3. earth wire

  4. none of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

During wiring in our houses , we use the traditional concept of using red color wire as live , black as neutral and green for earth.These color codes are used to distinguish between live, neutral and earth. which is a standard way of coding of colors for electric connections.

Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

Which of the following relations is correct?

  1. $E = mc$

  2. $E = mc^2$

  3. $E = 2mc^2$

  4. $E = mc^2/4$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

According to Einstein, energy and mass are related by the relation.
$E = mc^2$
where c is the speed of light in vacuum.

Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

One milligram of matter is converted into energy. The energy released will be

  1. $9\times 10^{6} J$

  2. $9\times 10^{8}J$

  3. $9\times 10^{10}J$

  4. $9\times 10^{12}J$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Here, $m = 1\ mg = 1\times 10^{-3} g $

             $= 1\times 10^{-6}kg$
According to Einstein mass-energy equivalence
                $E = mc^{2}$
where $c$ is the speed of light in vacuum
$\therefore E = (1\times 10^{-6} kg)(3\times 10^{8}ms^{-1})^{2}$
$ = 9\times 10^{10}J$.

Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

The relation between the volume $V$ and the mass $M$ of a nucleus is:

  1. $V\propto M^{3}$

  2. $V\propto M^{1/3}$

  3. $V\propto M$

  4. $V\propto 1/M$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Since the density of nucleus is fixed.

$D=\cfrac { M }{ V } \ \Rightarrow M=DV\ M\propto V$

Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

A student wrote the relation for one unified atomic mass unit (u) as $1u=931.5MeV$. What is the correct relation?

  1. $1 u\times c=931.5 MeV$

  2. $1 u\times c^2=931.5 MeV$

  3. $\dfrac{1u}{c^2}=931.5 MeV$

  4. $(1u)^2\times c=931.5Me V$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$1u=931.5 MeV$
we know $1u=1.66\times 10^{-21}kv$
$931.5 MeV=931.5\times 10^6\times 1.6\times 10^{-19}J=1.49\times 10^{-10}$
$E=(1u)(c^2)=(1.66\times 10^{-27})(3\times 10^8)^2J=1.494\times 10^{-10}J$
so $(1u)(c)^2=931.5MeV$

Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

A nucleus of mass number $A$ originally at rest emits $\alpha$- particle with speed $v$. The recoil speed of daughter nucleus is:

  1. $\cfrac{4v}{A-4}$

  2. $\cfrac{4v}{A+4}$

  3. $\cfrac{v}{A-4}$

  4. $\cfrac{v}{A+4}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

By conservation of momentum, the momentum of the alpha particle (mass 4, speed v) must equal the momentum of the daughter nucleus (mass A-4, speed V). Thus, 4v = (A-4)V, so V = 4v / (A-4).