For which frequency of light, the eye is most sensitive? - Physics

Advertisements
Advertisements
MCQ

For which frequency of light, the eye is most sensitive?

Options

  • 6.1 × 1014 Hz

  • 5.36 × 1014 Hz

  • 4.87 × 104 Hz

  • 8.16 × 1014 Hz

Advertisements

Solution

5.36 × 1014 Hz

Explanation:

Light weave length is most sensitive to the eye.

`lambda = 5600 xx 10^-10` m.

As a result, its frequency `r = c/lambda = (5 xx 10^8)/(5600 xx 10^-10)`

= `5.36 xx 10^14` Hz.

  Is there an error in this question or solution?

RELATED QUESTIONS

How are electromagnetic waves produced? 


Write any two important properties of electromagnetic waves.


Do electromagnetic waves carry energy and momentum ?


What is the ratio of the speed of gamma rays to that of radio waves in a vacuum?


How are electric vector `(vec "E")`, magnetic vector `(vec "B")` and velocity vector `(vec "C")` oriented in an electromagnetic wave?


 Which segment of electromagnetic waves has highest frequency? How are these waves produced? Give one use of these waves.


How does a charge q oscillating at certain frequency produce electromagnetic waves?

Sketch a schematic diagram depicting electric and magnetic fields for an electromagnetic wave propagating along the Z-direction.


In a microwave oven, the food is kept in a plastic container and the microwaves is directed towards the food. The food is cooked without melting or igniting the plastic container. Explain.


A capacitor is connected to an alternating-current source. Is there a magnetic field between the plates?


Can an electromagnetic wave be polarised?


An electromagnetic wave going through vacuum is described by
E = E0 sin (kx − ωt); B = B0 sin (kx − ωt).
Which of the following equations is true?


Speed of electromagnetic waves is the same


Which of the following have zero average value in a plane electromagnetic wave?
(a) Electric field
(b) Magnetic field
(c) Electric energy
(d) Magnetic energy


The energy contained in a small volume through which an electromagnetic wave is passing oscillates with


A point charge is moving along a straight line with a constant velocity v. Consider a small area A perpendicular to the motion of the charge. Calculate the displacement current through the area when its distance from the charge is x. The value of x is not large, so that the electric field at any instant is essentially given by Coulomb's law.


A laser beam has intensity 2.5 × 1014 W m−2. Find amplitudes of electric and magnetic fields in the beam.


The energy associated with light of which of the following colours is minimum : 


This is an example of step-up transformer .


Define frequency modulation and state any one advantage of frequency modulation (FM) over amplitude modulation (AM). 


State any one property which is common to all electromagnetic waves.


The energy levels of an atom of a certain element are shown in the given figure. Which one of the transitions A, B, C, D or E will result in the emission of photons of electromagnetic radiation of wavelength 618.75 nm? Support your answer with mathematical calculations.


An e.m. wave is propagating in a medium with a velocity `vec"v" = "v" hat"i"`. The instantaneous oscillating electric field of this e.m. wave is along +y-axis, then the direction of an oscillating magnetic field of the e.m. wave will be along:


Fraunhofer lines are an example of _______ spectrum.


Give two uses of Microwaves.


Write a short note on the microwave.


Write a short note on the radio waves.


Write a short note on the visible spectrum.


Discuss the Hertz experiment.


Discuss the source of electromagnetic waves.


Explain the types of absorption spectrum.


A pulse of light of duration 10-6 s is absorbed completely by a small object initially at rest. If the power of the pulse is 60 x 10-3 W, calculate the final momentum of the object.


In plane electromagnetic wave propagation velocity v, wavelength λ and frequency ν are related by ______.


A man standing on the road has to hold his umbrella at 30° with the vertical to keep the rain away. He throws away the umbrella and starts, running at 10 km/h and finds raindrops hitting his head vertically. The speed of the raindrops with respect to the road is ______.


Which one of the following does not represent simple harmonic motion? Here y denotes the instantaneous displacement. Here, A and B are constants and co is the angular frequency.


A plane electromagnetic wave travels in free space along x-axis. At a particular point in space, the electric field along y-axis is 9.3 Vm−1. The magnetic induction (B) along z-axis is:


Dimensions of 1/(µOE0) is


Which of the following electromagnetic radiations has the smallest wave length?


An accelerate electron would produce.


If a source is transmitting electromagnetic waves of frequency 8.2 × 106 Hz. then wavelength of electromagnetic waves transmitted from the source will be.


The velocity of electromagnetic wave is parallel to


Which of the following are not electromagnetic waves?


The sun delivers 103w/m2 of electromagnetic flux to the earth's surface. The total power that is incident on a roof of dimension 8m/10m will be


Electromagnetic waves are produced by ______.


Which of the following type of radiations are radiated by an oscillating electric charge?


For a plane electromagnetic wave propagating in x-direction, which one of the following combinations gives the correct possible directions for electric field (E) and magnetic field (B) respectively?


For a plane electromagnetic wave propagating in the x-direction, which one of the following combinations gives the correct possible directions for the electric field (E) and magnetic field (B) respectively?


A linearly polarized electromagnetic wave given as E = Eoî cos (kz – ωt) is incident normally on a perfectly reflecting infinite wall at z = a. Assuming that the material of the wall is optically inactive, the reflected wave will be given as ______.


An EM wave radiates outwards from a dipole antenna, with E0 as the amplitude of its electric field vector. The electric field E0 which transports significant energy from the source falls off as ______.


A charged particle oscillates about its mean equilibrium position with a frequency of 109 Hz. The electromagnetic waves produced ______.

  1. will have frequency of 109 Hz.
  2. will have frequency of 2 × 109 Hz.
  3. will have a wavelength of 0.3 m.
  4. fall in the region of radiowaves.

Poynting vectors S is defined as a vector whose magnitude is equal to the wave intensity and whose direction is along the direction of wave propagation. Mathematically, it is given by `S = 1/mu_0 E xx B`. Show the nature of S vs t graph.


A plane EM wave travelling in vacuum along z direction is given by `E = E_0 sin(kz - ωt)hati` and `B = B_0 sin(kz - ωt)hatj` 

  1. Evaluate `oint E.dl` over the rectangular loop 1234 shown in figure.
  2. Evaluate `int B.ds` over the surface bounded by loop 1234.
  3. Use equation `oint E.dl = (-dphi_B)/(dt)` to prove `E_0/B_0` = c.
  4. By using similar process and the equation `ointB.dl = mu_0I + ε_0 (dphi_E)/(dt)`, prove that c = `1/sqrt(mu_0ε_0)`


The intensity of the light from a bulb incident on a surface is 0.22 W/m2 . The amplitude of the magnetic field in this light-wave is ______× 10–9 T. 

(Given: Permittivity of vacuum ε0 = 8.85 × 10–12 C2 N–1 – m–2, speed of light in vacuum c = 3 × 108 ms-1)


A plane electromagnetic wave of frequency 500 MHz is travelling in a vacuum along a y-direction.

At a particular point in space and time, `vec"B"` = 8.0 × 10-8 `hat"Z"`T. The value of the electric field at this point is ______.

(speed of light = 3 × 108 ms-1)

`hat x, hat y, hat z` are unit vectors along x, y, and Z directions.


A plane electromagnetic wave, has frequency of 2.0 × 1010 Hz and its energy density is 1.02 × 10-8 J/m3 in vacuum. The amplitude of the magnetic field of the wave is close to `(1/(4piepsilon_0) = 9xx10^9"Nm"^2/"C"^2  "and speed of light" = 3 xx 10^8  "m"  "s"^-1)`:


A plane electromagnetic wave travels in free space along the x-direction. The electric field component of the wave at a particular point of space and time is E = 6 Vm-1 along the y-direction. Its corresponding magnetic field component, B would be ______.


Sunlight falls normally on a surface of area 36 cm2 and exerts an average force of 7.2 × 10-9 N within a time period of 20 minutes. Considering a case of complete absorption the energy flux of incident light is ______.


The electric field in an electromagnetic wave is given by E = 56.5 sin ω(t - x/c)Nc-1. Find the intensity of the wave if it is propagating along x-axis in the free space.

(Given ε0 = 8.85 × 10-12 C2 N-1 m-2)


A plane electromagnetic wave with frequency of 30 MHz travels in free space. At particular point in space and time, electric field is 6 V/m. The magnetic field at this point will be x × 10-8 T. The value of x is ______.


An electromagnetic wave of frequency 3 GHz enters a dielectric medium of relative electric permittivity 2.25 from vacuum. The wavelength of this wave in that medium will be ______ × 10-2 cm. 


A 27 mW laser beam has a cross-sectional area of 10 mm2. The magnitude of the maximum electric field in this electromagnetic wave is given by:

[Given permittivity of space ∈0 = 9 × 10-12 SI units, Speed of light c = 3  108 m/s] 


An electromagnetic wave of frequency v = 3.0 MHz passes from vacuum into a dielectric medium with permittivity ∈ = 4.0. Then ______.


Name the electromagnetic wave/radiation which is used to study crystal structure.


Share
Notifications



      Forgot password?
Use app×