CBSE Questions for Class 12 Medical Physics Electromagnetic Waves Quiz 3 - MCQExams.com

The wavelength of light visible to eye is of the order of
  • $$10^{-4}m$$
  • $$10^{-8}m$$
  • $$10^{-10}m$$
  • $$10^{-7}m$$
According to Maxwell's hypothesis, changing of electric field give rise to 
  • Magnetic field
  • Pressure gradient
  • Charge
  • Voltage
_________ are useful in studying the structures of crystals. 
  • All electromagnetic radiations
  • Light rays
  • X-rays
  • $$\gamma$$-rays
Why does radio reception improve slightly during the night ? 
  • The outside noise is reduced very much at night.
  • Unlike the daytime, only a few radio stations broadcast during the night.
  • Sunlight affects radio broadcasts to some extent during the day.
  • The magnetic field of the earth acts with reduced intensity during the night, thereby reducing its impact on broadcasts.
Who first proposed the light as an electromagnetic wave ?
  • Thomas Young
  • Max planck
  • James Clerk Maxwell
  • Albert Einstein
The increasing order of frequencies for infrared rays, Ultraviolet rays-, X-rays and Y-rays will be-
  • y-rays, X-rays, Infrared rays, Ulterviolet rays
  • X-rays,Y-rays Infrared rays,Ultraviolet rays
  • Infrared rays, Ultraviolet rays,X-rays, Y-rays
  • Ultraviolet rays,X-rays, Y-rays Infrared rays
_______ is the characteristic of colour
  • Wavelength
  • Frequency
  • Speed
  • None of the above
EM waves are
  • deflected by electric and magnetic waves
  • not deflected by electric and magnetic waves
  • sometimes deflected sometimes not deflected
  • none of the above
The portion of the spectrum beyond the red end is called
  • UV spectrum
  • Infrard spectrum
  • Microwave
  • All
Most energetic radiations and fluorescence are properties of 
  • Gamma rays
  • UV Rays
  • Infrared Rays
  • Radio waves
Gamma rays have frequency(f)
  • $$f > 3 \times 10^{19} Hz$$
  • $$7.5 \times 10^{14}Hz < f < 3 \times 10^{16} Hz$$
  • $$<3 \times 10^7 Hz$$
  • None of the above
When an object absorb waves  and  energy their temperature increases.
  • True
  • False
If $$c$$ is the speed, $$\nu$$ is frequency and $$\displaystyle \lambda $$ is wavelength of EM waves, then
  • $$\displaystyle c=\nu\lambda $$
  • $$\displaystyle \frac { \lambda }{ \nu } =c$$
  • $$\displaystyle \frac { \nu }{ \lambda } =c$$
  • $$\displaystyle \frac { 1 }{ \lambda } =\frac { c }{ \nu} $$
EM waves travels with a speed of
  • 260m/s
  • $$\displaystyle 3\times { 10 }^{ 8 }m/s$$
  • $$\displaystyle 22\times { 10 }^{ 18 }m/s$$
  • 2m/s
On changing of medium, ______ remains same.
  • Wavelength
  • Frequecy
  • Speed
  • None
How can Infrared radiations be harmful for humans
  • Can cause blindness
  • Can cause skin burns
  • Can cause hairfall
  • Can cause frostbite
Which of the following is absorbed by the ozone layer ?
  • only gamma rays
  • visible light
  • radio waves
  • ultraviolet
Electromagnetic waves exhibit the property of
  • Reflection
  • Refraction
  • Total internal reflection
  • Both A and B
Where are radiowaves used?
  • Radar, radio and tv communications
  • Microwave ovens
  • Photographic films
  • sterilizing purpose
Electromagnetic theory suggests that the light consists of:
  • Magnetic vector only
  • Electric vector only
  • Electric and magnetic vectors perpendicular to each other
  • Parallel electric and magnetic vector
Which of the following are use of microwaves?
  • They are used for satellite communication.
  • They are used for analysis of atomic and molecular structure.
  • They are used cooking in microwave ovens.
  • All of the above.
What are the harmful effects of ultraviolet radiations?
  • It can cause skin cancer.
  • It contributes to global warming.
  • It contributes to greenhouse effect.
  • It can cause depletion of natural resources.
The electromagnetic waves travel in free space with the velocity of
  • Sound
  • Light
  • Greater than that of light
  • Greater than that of sound
Choose the correct answer from the alternatives given.
Which of the following electromagnetic waves have the smallest wavelength?
  • $$\gamma$$-rays
  • $$X$$-rays
  • UV waves
  • Infrared rays
Which of the following is not an electromagnetic wave?
  • Light rays
  • X-rays
  • Alpha rays
  • Gamma rays
Which of the following types of waves travels at the greatest speed through the vacuum?
  • Radio waves
  • Microwaves
  • Ultraviolet light
  • $$X$$-rays
  • None of the above; all these waves would travel at the same speed
Infrared radiation was discovered in $$1800$$ by.
  • William Wollaston
  • William Herschel
  • Wilhelm Roentgen
  • Thomas Young
Electromagnetic waves of wavelength ranging from $$100\mathring{A}$$ to $$\mathring{A}$$ comes under 
  • X-rays
  • UV regions
  • Visible region
  • Infrared region
The electromagnetic wave travel in free space with the velocity of 
  • Sound
  • Light
  • Greater than that of light
  • Greater than that of sound
In electromagnetic wave, according to Maxwell, changing electric field gives _______.
  • stationary magnetic field
  • conduction current
  • eddy current
  • displacement current
Electromagnetic theory suggests that the light consists of
  • Magnetic vector only
  • Electric vector only
  • Electric and magnetic vector perpendicular to each other
  • Perpendicular electric and magnetic vector
Which of the following light has the combination of all frequencies of visible light ?
  • white light
  • black light
  • ultraviolet light
  • infrared light
  • transparency
Identify most suitable options for the following vacant space. The visible light spectrum sits between the _____and _______regions of the electromagnetic spectrum.
  • infrared; ultraviolet
  • infrared; X-ray
  • infrared; gamma ray
  • microwave; ultraviolet
  • radio; ultraviolet
According to the electromagnetic spectrum, As the frequencies of the pure spectral colours increase, the wavelengths of the colours:
  • decrease
  • increase
  • remain the same
  • decrease by a factor of 2
  • increase by a factor of 2
According to the electromagnetic spectrum. Which of the following is NOT a pure spectral colour?
  • white
  • violet
  • red
  • blue
  • yellow
Identify which of the following is NOT a characteristic of electromagnetic waves?
  • contain electrical properties
  • have crests and troughs
  • contain magnetic properties
  • travel through space
  • have crests but no troughs
Identify the waves with the largest wavelengths .
  • Radio
  • Gamma Rays
  • X-Rays
  • Visible Light
  • Infrared Radiation
According to the electromagnetic spectrum, radio waves have the ______frequency and the  __________ wavelength.
  • lowest; largest
  • lowest; smallest
  • highest; smallest
  • highest; largest
  • medium; medium
Fill the most suitable option. Mosquitoes and some snakes find their food using vision in the ___ range.
  • infrared
  • ultraviolet
  • radio
  • microwave
  • visible light
Of the following waves has the longest wavelength?
  • X-rays
  • Green light
  • Orange light
  • Microwaves
  • Gamma rays
If a particular electromagnetic wave has the highest frequencies among the other electromagnetic waves then it should have the smallest
  • wavelengths
  • speeds
  • amplitudes
  • energies
  • periods
In an electromagnetic spectrum, identify which of the following lists are ordered from longest wavelength to shortest wavelength?
  • X ray, ultraviolet, visible light
  • visible light, ultraviolet , X-ray
  • ultraviolet, X-ray, visible light
  • ultraviolet, visible light, X-ray
  • X-ray, visible light, ultraviolet
In photocell cesium, coated oxidized silver cathode emits electrons for
  • visible light.
  • ultraviolet.
  • infrared light.
  • x-rays.
Identify which of the following is NOT a source of visible light?
  • red-hot metal
  • cool metal
  • fluorescent bulb
  • the Sun
  • fire
Which of the following colors of light has the lowest frequency?
  • Yellow
  • Violet
  • Orange
  • Blue
  • Green
Maxwell introduced displacement current to remove the conceptual contradiction in 
  • Gauss's law in electrostatics
  • Gauss's law in magnetism
  • Faraday's law
  • Ampere's law
Maxwell's corrections to Ampere's law was required when the later was extended to:
  • a static situation
  • a non-static situation
  • a semi-static situation
  • a quasi-static situation
Fill in the blanks. 
Current flowing through the resistor is known as ________ , while the current flowing through the capacitor is commonly known as _______. 
  • eddy current, displacement current
  • displacement current , conduction current
  • conduction current, eddy current
  • conduction current, displacement current
State whether true or false :
Ultraviolet rays are used to take photographs in darkness.
  • True
  • False
Which of the following is/are electromagnetic wave(s)?
  • Microwaves
  • Radio wave
  • Infrared radiation
  • All of the above
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