Tag: electromagnetic waves

Quizzes (7) Questions (222)

Questions Related to electromagnetic waves

Multiple choice electromagnetic spectrum electromagnetic waves physics

Electromagnetic wave of intensity $1400\ W/m^{2}$ falls on metal surface on area $1.5\ m^{2}$ is completely absorbed by it. Find out force exerted by beam.

  1. $14\times 10^{-5}N$
  2. $14\times 10^{-6}N$
  3. $7\times 10^{-5}N$
  4. $7\times 10^{-6}N$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
For a perfectly absorbing surface,
$F=\dfrac{IA}{C}$

$=\dfrac{(1400w/m^2\times 1.5m^2)}{(3\times 10^8m/s)}$

$=7\times 10^{-6}N$.
Multiple choice electromagnetic spectrum electromagnetic waves physics

Which one of the following is the primary effect of UV radiation caused due to depletion of ozone layer?

  1. Heart attack

  2. Skin cancer

  3. High fever

  4. All of these

  5. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The ozone layer prevents most harmful UV wavelengths of ultraviolet light (UV light) from passing through the Earth's atmosphere. These wavelengths cause skin cancer, sunburn and cataracts, which were projected to increase dramatically as a result of thinning ozone, as well as harming plants and animals.

Multiple choice electromagnetic spectrum electromagnetic waves physics

A gas of identical hydrogen like atoms has some atoms in ground state and some atoms in a particular excited state and there are no atoms in any other energy level. The atoms of the gas make transition to a higher state by absorbing monochromatic light of wavelength $304 \AA $. subsequently, the atoms emit radiation of only six different photon energies. Some of emitted photons have wavelength $304 \AA $, some have wavelength more and some have less than $304 \AA $ ( Take $hc = 12420 eV - \AA $)
Find the principal quantum number of the initially excited state.

  1. 1

  2. 2

  3. 3

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

The energy of the absorbed photon is E = hc/lambda = 12420/304 approx 40.8 eV. For a hydrogen-like atom, E = 13.6 * Z^2 * (1/n1^2 - 1/n2^2). Given the emission of 6 lines, the final state must be n=4 (since 4*3/2 = 6). The transition is from n_initial to n_final = 4. Solving for Z and n_initial requires specific energy level data.

Multiple choice electromagnetic spectrum electromagnetic waves physics

A gas of identical hydrogen like atoms has some atoms in ground state and some atoms in a particular excited state and there are no atoms in any other energy level. The atoms of the gas make transition to a higher state by absorbing monochromatic light of wavelength $304 \mathring A $. subsequently, the atoms emit radiation of only six different photon energies. Some of emitted photons have wavelength $304 \mathring A $, some have wavelength more and some have less than $304 \mathring A $ ( Take $hc = 12420 eV - \mathring A $). Find the principal quantum number of the initially excited state.

  1. 1

  2. 2

  3. 3

  4. 4
Reveal answer Fill a bubble to check yourself
A Correct answer
Multiple choice electromagnetic spectrum electromagnetic waves physics

A gas of identical hydrogen like atoms has some atoms in ground state and some atoms in a particular excited state and there are no atoms in any other energy level. The atoms of the gas make transition to a higher state by absorbing monochromatic light of wavelength $304 \mathring A $. subsequently, the atoms emit radiation of only six different photon energies. Some of emitted photons have wavelength $304 \mathring A $, some have wavelength more and some have less than $304 \mathring A $ ( Take $hc = 12420 eV - mathring A $). Find the principal quantum number of the initially excited state.

  1. 1

  2. 2

  3. 3

  4. 4
Reveal answer Fill a bubble to check yourself
A Correct answer
Multiple choice electromagnetic spectrum electromagnetic waves physics

Mark the correct option in impure spectrum :

  1. Order of colours is reverse

  2. Order of colours is irregular

  3. colours are overlapped

  4. no colours is present
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

For impure spectrum:

  1. The order of colours is are straight, hence option a is false
  2. Order of colours are regular
  3. Colours are overlapped each other in impure spectrum
  4. Colours are present in impure spectrum
Hence option C is the correct statement according to the impure spectrum

Multiple choice electromagnetic spectrum electromagnetic waves physics

Radiations of intensity 0.5 W/m2 are striking a metal plate. The pressure on the plate is

  1. $0.166 \times 10^{-8} N/m2$
  2. $0.332 \times 10-8 N/m^2$
  3. $0.111 \times 10-8 N/m^2$
  4. $0.083 \times 10-8 N/m^2$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Intensity or power per unit area of the radiations,
$P = pv$
$\Rightarrow p=\dfrac{p}{v} = \dfrac{0.5}{3\times 10^8}=0.166\times 10^{-8}N/m^2$

Multiple choice electromagnetic spectrum electromagnetic waves physics

Radiation pressure on any surface :

  1. is dependent on wavelength of the light used

  2. is dependent on nature of surface and intensity of light used

  3. is dependent on frequency and nature of surface

  4. depends on the nature of source from which light is coming and on nature of surface on which it is falling.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Radiation pressure is given by   $P _R = \dfrac{(1+\alpha) I}{c}$
where $\alpha$ is the coefficient of reflection of the surface.
For completely reflecting surface  $\alpha =1$
For completely absorbing surface  $\alpha = 0$
So,  radiation pressure depends on the nature of surface on which the light is falling but independent of wavelength of light falling.

Multiple choice the nature of electromagnetic waves space exploration and forms of light observing space: telescopes electromagnetic waves physics

Choose the correct answer from the alternatives given.
Maxwell in his famouse questions of  eletromagnetism introduce the concept of:

  1. ac current

  2. displacement current

  3. impedance

  4. reatance
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Maxwell in his famous question's of electromagnetism introduce the concept of displacement current

$J=J _E+J _C\ \quad=\epsilon _0\cfrac{dE}{dT}+\cfrac{dP}{dT}$

Multiple choice the nature of electromagnetic waves space exploration and forms of light observing space: telescopes electromagnetic waves physics

Which of the following has/have zero average value in a plane electromagnetic wave?

  1. Both magnetic and electric fields

  2. Electric fields only

  3. Magnetic field only

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Both electric and magnetic field have sinusoidal nature in a plane electromagnetic wave. As we know, the average value of a sinusoidal wave is zero, so both magnetic and electric fields have average values zero.