MCQ Questions for Class 12 Medical Physics Electromagnetic Waves Quiz 2

Identify which of the following light rays has the highest energy?

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Violet
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Green
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Yellow
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Orange
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Red

Explanation

Energy of light ray

$E = h\nu$

$\implies E \propto \nu$

Among all the visible rays, violet ray has the highest frequency, Thus violet ray has the highest energy.

Name the region beyond the violet end, of the spectrum

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infraviolet
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ultraviolet
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darkviolet
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lightviolet

Name the radiations of wavelength just longer than

$8\times 10^{-7}m$ .

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infrared
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ultrared
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infraviolet
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ultraviolet

Explanation

In the order of increasing wavelength, the waves are Gamma rays (

$< 1 nm$ ), X-rays (

$1-10 nm$ ), infrared rays (

$700-{ 10 }^{ 5 }nm$ ), micro waves (

${ 10 }^{ 5 }-{ 10 }^{ 8 }nm$ ), radio waves (

${ >10 }^{ 8 }nm$ ).
Hence, the radiations of wavelength just longer than

${ 8\times 10 }^{ -7 }m$ is Infrared.

The source of ultraviolet light is:

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electric bulb
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red hot iron ball
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sodium vapour lamp
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carbon arc-lamp

Two waves

$A$ and

$B$ have wavelength

$0.01A^o$ and

$9000A^o$ respectively. Name the two waves.

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A-gamma, B-infrared
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A-gamma, B-ultraviolet
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A-ultraviolet, B-infrared
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A-gamma, B-X rays

Explanation

Electromagnetic radiation is classified into types according to the frequency of the wave. These types include, in order of increasing frequency, radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays and gamma rays.
The frequency is the inverse of wavelength. Hence, in the order of increasing wavelength, the waves are Gamma rays (

$<1 nm$ ), X-rays (

$1-10 nm$ ), infra red rays (

$700-{ 10 }^{ 5 }nm$ ), micro waves (

${ 10 }^{ 5 }-{ 10 }^{ 8 }nm$ ), radio waves (

${ >10 }^{ 8 }nm$ ). Therefore, the range of the electromagnetic spectrum is

$0.01A\quad to\quad 9000A$ .
Hence, the wave A with wavelength of $0.01A$ is Gamma rays and the wave B with wavelength of $9000A$ is radio waves.

Name the rays or waves of highest frequency.

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X-rays
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UV rays
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IR rays
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Gamma rays

Explanation

The electromagnetic spectrum in order of increasing frequency is - radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays and gamma rays.
The frequency of the gamma rays is

${ >3\times 10 }^{ 19 }m$ .
Hence, the gamma rays has the maximum frequency in the electromagnetic spectrum.

Name the radiation which can be detected by a solution of silver chloride.

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X-ray radiation
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ultraviolet radiation
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infrared radiation
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visible radiation

Displacement current is

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continuous when electric field is changing in the circuit
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continuous when magnetic field is changing in the circuit
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continuous in both types of fields
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continuous through wires and resistance only

What is the speed of Light

$c$ ?

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$c=3\times 10^{-8} m s^{-1}$
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$c=3\times 10^8 km s^{-1}$
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$c=3\times 10^8 mm s^{-1}$
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$c=3\times 10^8 m s^{-1}$

According to Maxwell's equation, the velocity of light in any medium is expressed as

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$\displaystyle\frac{1}{\sqrt{\mu_0\varepsilon_o}}$
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$\displaystyle\frac{1}{\sqrt{\mu\varepsilon}}$
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$\displaystyle\sqrt{\frac{\mu}{\varepsilon}}$
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$\displaystyle\sqrt{\frac{\mu_0}{\varepsilon}}$

Explanation

Velocity of light in a medium,

$\displaystyle c=\frac{1}{\sqrt{\mu_0\varepsilon_o\mu_r\varepsilon_r}}=\frac{1}{\sqrt{\mu\varepsilon}}$

An electromagnetic wave has a frequency of

$500MHz$ and a wavelength of

$60cm$ . Calculate the velocity of the wave.

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$3\times 10^8kms^{-1}$
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$3\times 10^8cms^{-1}$
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$3\times 10^{-8}ms^{-1}$
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$3\times 10^8ms^{-1}$

Explanation

The formula for velocity, when given wavelength and the frequency of the wave, is written as:

$v=f\lambda$ .
In this formula,

$f$ represents frequency,

$v$ represents the velocity of the wave, and

$\lambda$ represents the wavelength of the wave.
Here, the frequency of the wave is

$500 MHz = 500000000 Hz$ and the wavelength is

$60 cm = 0.6 m$
Hence, the velocity of the wave is

$3\times { 10 }^{ 8 }m/s$ .

Microwaves are detected by

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barometer
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point contact diodes
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thermopiles
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the eye

State whether given statement is True or False

MRI uses radio-waves.

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True
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False

The displacement current was first populated by

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Maxwell
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Marconi
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Ampere
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Hertz

Which of the following has the shortest wavelength?

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Red light
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Blue light
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Gamma rays
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X rays
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Radio waves

A group of wavelengths is called

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Wave
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Echo
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Sound Wave
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Spectrum

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

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Electric
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Magnetic
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Thermoelectric
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Electromagnetic

Explanation

$Answer:-$ D

Any stationary charge produce static electric field. And the field strength is given by:

r, is the radial distance from the point charge.
Q, is the charge in Coulomb.

When electric charge oscillates electric field at any point also oscillates.And according to Maxwell's equations varying electric field produces magnetic field and an oscillating electric field produces oscillating magnetic field.
This thing is used in antennas in which oscillating current of certain frequency produces oscillating electric and magnetic field which propagates through space(electromagnetic waves).

Fraunhofer spectral lines are called:

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Line absorption spectra
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Line emission spectra
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continuous spectra
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Continuous emission spectra

Which of the following solar radiations pass through the atmosphere of earth:
X-rays, ultraviolet rays, visible light rays, infrared radiation.

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X-Ray
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Ultraviolet
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Visible
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Infrared

$v_s$ ,

$v_x$ and

$v_m$ are the speed of soft gamma rays, X-rays and microwaves respectively in vacuum, then

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$v_s > v_x > v_m$
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$v_s < v_x < v_m$
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$v_s > v_x < v_m$
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$v_s = v_x = v_m$

Explanation

$Answer:-$ D

All have different frequency and wavelength but since all are electomagnetic waves so have same speed equal to that of light (

$c=3\times10^8m/s$ ).

Which one of the following rays has minimum frequency?

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Ultraviolet rays
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X-rays
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$\gamma$ -rays
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Infra-red rays

Explanation

$Answer:-$ D

See the figure u will note that among given four options infrared rays have highest wavelength and lowest frequency.

Which of the following electromagnetic radiations have the smallest wavelength?

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Ultraviolet waves
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X-rays
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$\gamma$ -rays
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Microwaves

Explanation

$Answer:-$ C

See the figure u will note that gamma rays have smallest wavelength and highest frequency.

Which of the following electromagnetic waves has the longest wavelength?

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Heat waves
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Visible light
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Radio frequency waves
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Microwaves

Explanation

$Answer:-$ C

In the image we can see that radio waves have longest wavelength and lowest frequency.

Maxwell's equation describe the fundamental laws of

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electricity
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magnetism
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mechanics
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both (A) and (B)

Radio waves with frequencies higher than television signals are

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ultrasonic waves
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sound waves
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light waves
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microwaves

The frequencies of X-rays,

$\gamma$ -rays and ultraviolet rays are respectively a, b and c. Then

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$a < b$ , $b>c$
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$a>b$ , $b>c$
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$a>b$ , $b < c$
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$a < b$ , $b < c$

Explanation

The frequency of

$\gamma-$ rays is more than that of X-rays.

In an electromagnetic wave, the direction of the magnetic induction

$\vec{B}$ is

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parallel to the electric field $\vec{E}$
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perpendicular to the electric field $\vec{E}$
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antiparallel to the pointing vector $\vec{S}$
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random

Explanation

$Answer:-$ B

The electric field is always perpendicular to the magnetic field, and both fields are directed at right-angles to the direction of propagation of the wave. In fact, the wave propagates in the direction

$\vec{E} \times \vec{B}$ . Electromagnetic waves are clearly a type of transverse wave.

The electromagnetic waves do not transport

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energy
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charge
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momentum
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information

Explanation

$Answer:-$ B

EM waves carry energy (light ), momentum (can be seen by photoelectric experiment) and information (like radiowaves ) but does'nt carry charge.

Which of the following is of shortest wavelength?

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X-rays
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$\gamma$ -rays
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Microwaves
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Radio waves

Explanation

$Answer:- B$

We can see that gamma rays have highest frequency and so lowest wavelength.

Radio waves of constant amplitude can be generated with

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rectifier
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filter
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F.E.T
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oscillator

Explanation

$Answer:-$ D option

An electronic oscillator is an electronic circuit that produces a periodic, oscillating electronic signal, often a sine wave or a square wave.

the wave produced has a constant amplitude throughout.

while rectifier,filter,FET produce variable amplitudes.

$10\:cm$ is a wavelength corresponding to the spectrum of

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infrared rays
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ultraviolet rays
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microwaves
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$\gamma$ -rays

Explanation

Microwave region wavelength

$={10}^{-3}\:m$ to

$1\:m$

A radar sends the waves towards a distant object and receives the signal reflected by object. These waves are

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sound waves
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light waves
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radio waves
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microwaves

Explanation

$Answer:-$ C and D option

A radar system consists of a transmitter producing electromagnetic waves in the radio or microwave domain, an emitting antenna, a receiving antenna (separate or the same as the previous one) to capture any returns from objects in the path of the emitted signal, a receiver and processor to determine properties of the object(s).

According to Maxwell's hypothesis, a changing electric field gives rise to

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an electromagnetic force
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electric displacement current
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magnetic field
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pressure gradient

Explanation

$Answer:-$ C option

$\nabla \times B={ \mu }_{ 0 }(J+{ \epsilon }_{ 0 }\dfrac { dE }{ dt } )$

using this equation of maxwell we can say changing electric field

$\dfrac{dE}{dt}$ induces magnetic field.

Find out the wavelength of violet light which has a frequency of

$7.5 \times 10^{14}Hz$ ?

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$2.25\times 10^{23}m$
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$2.5\times 10^{5}m$
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$4\times 10^{-7}m$
0%
$7.5\times 10^{-7}m$
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$2.25\times 10^{7}m$

Explanation

Given :

$\nu = 7.5 \times 10^{14}$ Hz

Speed of violet light (EM wave)

$v = 3 \times 10^8$ m/s

Thus wavelength of violet light

$\lambda = \dfrac{v}{\nu} = \dfrac{3 \times 10^8}{7.5 \times 10^{14}} =4 \times 10^{-7}$ m

Which of the following radiations has the least wavelength?

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$\gamma$ -rays
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$\beta$ -rays
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$\alpha$ -rays
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X-rays

It is possible to take pictures of those objects which are not fully visible to the eye using camera films sensitive to

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ultraviolet rays
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infrared rays
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microwaves
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radiowaves

$\lambda=10\:\mathring{A}$ then it corresponds to :

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infrared
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microwaves
0%
ultraviolet
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X-rays

Explanation

$\lambda=10\:\mathring{A}=10\times{10}^{-10}\:m={10}^{-9}\:m$
X-ray wavelength is of the order of

$10{\mathring A}$

Fluorescent tubes give more light than a filament bulb of same power because

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the tube contains gas at low temperature
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ultraviolet light is converted into visible light by fluorescence
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light is diffused through the walls of the tube
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it produces more heat than bulb

Electromagnetic waves are transverse in nature is evident by

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polarization
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interference
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reflection
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diffraction

An accelerated electron would produce

0%
$\gamma$ -rays
0%
$\beta$ -rays
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$\alpha$ -rays
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electromagnetic rays

Explanation

$Answer:-$ D

An electron carries an electric charge. A stationary electron creates no magnetic field. (Like a wire with no current). An electron moving at constant velocity generates a steady magnetic field, but (like a stationary magnet in a coil of wire) a constant magnetic field won't result in another electric field. An electron moving with a changing velocity (ie. accelerating), however, generates a changing magnetic field, which will produce a changing electric field, which produces a changing magnetic field, etc. In other words, it generates an electromagnetic wave.

Radio waves do not penetrate in the band of

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ionosphere
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mesosphere
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troposphere
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stratosphere

Explanation

$Answer:-$ A option

The ionization of gas particles in the ionosphere aids in the transmission of radio waves by reflecting waves back to Earth, rather than allowing them to escape the atmosphere. Solar flares, the spontaneous eruption of high-energy radiation from the surface of the sun, can cause a sharp increase in the number of ionized particles in the upper atmosphere and can interfere with radio wave transmissions.

Radio waves and visible light in vacuum have

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same velocity but different wavelength
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continuous emission spectrum
0%
band absorption spectrum
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line emission spectrum

Explanation

$Answer:-$ A

speed of electromagnetic wave in vacuum is given by:-

c(speed of light)=frequency

$\times$ wavelength =

$\dfrac{1}{\mu_0 \epsilon_0}$ =constant

as we go from gamma rays to radio waves frequency decreases and wavelength increases thereby maintaining the product constant.

so velocity is same but wavelength is different.

Astronauts communicate with one another on moon with the help of.

0%
radio waves
0%
sound waves
0%
ultrasound waves
0%
infrasound waves

Choose the correct answer from the alternatives given.
Radio waves diffract around building although light waves do not. The reason is that radio waves

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travel with speed larger than c
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have much larger wavelength than light
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are not electromagnetic waves
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None of these

Explanation

$Answer:-$ B

Both radio and light waves are EM waves, just in different frequency ranges. The wavelength of visible light is typically around the 600 nm range, which is 6/1000 of a millimeter (very small!). Radio waves on the other hand, often wave wavelengths of a few yards long. For a wave to diffract around an object, the size of the object must be on the same order of the wavelength of the wave.

Radiations used to get relief from bodyaches are:

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I.R. radiations
0%
U.V. radiations
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visible radiations
0%
none of these

For transmission of speeches, talks, music, dramas etc ........... is used

0%
radio broadcast transmitter
0%
radio telegraph transmitter
0%
navigation transmitter
0%
None of these

Explanation

$Answer:-$ A

Radio Broadcast Transmitters: -Theses transmitters are designed for transmitting speeches, talks, music, dramas etc for the information and reception of people. These broadcast transmitters may be either amplitude modulated or frequency modulated. The A.M transmitters operate on long waves, medium waves and short waves and radiate carrier power as low as about 1 kW and high as 100 kW. The F.M broadcast transmitters operate on very short waves or on ultra waves and radiate carrier power of the order of 100 kW or so.

In which one of the following regions of the electromagnetic spectrum will the vibrational motion of molecules give rise to absorption?

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Ultraviolet
0%
Microwaves
0%
Infrared
0%
Radio waves

The middle colour in sunlight spectrum is:

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yellow
0%
green
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blue
0%
orange

In which form does the Light propagates?

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Electric waves
0%
Magnetic waves
0%
Electromagnetic waves
0%
Sound wave

The broad wavelength range of visible spectrum is:

0%
$4000-8000A^o$
0%
$2000-4000A^o$
0%
$10000-20000A^o$
0%
None of the above

Explanation

The wavelength range of

$4000-8000 A^o$ is known as visible spectrum as waves within this wavelength range create a sensation of vision in our eyes.

CBSE Questions for Class 12 Medical Physics Electromagnetic Waves Quiz 2 - MCQExams.com

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Practice Class 12 Medical Physics Quiz Questions and Answers

CBSE Questions for Class 12 Medical Physics Electromagnetic Waves Quiz 2 - MCQExams.com

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Practice Class 12 Medical Physics Quiz Questions and Answers

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