HOTs Electromagnetic Waves Class 12 Physics

Please refer to Electromagnetic Waves HOTs Class 12 Physics provided below with Electromagnetic Waves. All HOTs for Class 12 Physics with answers provided below have been designed as per the latest syllabus and examination petter issued by CBSE, NCERT, KVS. Students of Standard 12 Physics should learn the solved HOTS for Class 12 Physics provided below to gain better marks in examinations.

Electromagnetic Waves Class 12 Physics HOTs

Assertion (A) & Reason(R)

A. Both assertion and reason are True, and reason is the correct explaination .
B. Both assertion and reason are True, but reason is not the correct explaination .
C. Assertion is True , but reason is False .
D. Both assertion and reason are False .

Question. Assertion: X-rays travel with the speed of light.
Reason: X-rays are electromagnetic rays.

Question. Assertion: Electromagnetic radiation exert pressure.
Reason: Electromagnetic waves carry both – Momentum & Energy.

Question. Assertion: During discharging, there is magnetic field between plates of capacitor.
Reason: Time varying electric field produces magnetic field.

Question. Assertion: In electromagnetic waves, electric and magnetic Field are perpendicular to each other.
Reason: E and B are self-sustaining.

Question. Assertion: The earth without its atmosphere would be inhospitably Cold.
Reason: All heat would escape in the absence of atmosphere.

Question. Assertion: The EM waves of shorter wavelength can travel longer distances on earth’s surface than those of longer wavelengths.
Reason: Shorter the wavelength, the larger is the Velocity of propagation.

Question. Assertion: EM waves follow Superposition principle.
Reason: Differential expression of EM wave is linear.

Question. Assertion: Sound waves cannot travel in vacuum, but light waves can.
Reason: Light is an electromagnetic wave – but sound is a Mechanical wave.

Question. Assertion: Transverse waves are not produced in liquids and gases.
Reason: Shorter the wavelength, the larger is the Velocity of propagation.

Question. Assertion: The energy contained in a small volume through which an em wave is passing,
oscillates with the frequency of the wave.
Reason: Energy density of the wave is given by : ½ e₀ E² .

Case Study Questions

Question. Microwave in aircraft navigation
Microwave are used in aircraft navigation. A radar guns out short bursts of microwave and it reflect back from oncoming aircraft and are detected by receiver in gun. The frequency of reflected wave used to compute speed of aircraft

Question. How are microwave produced?
a) klystron and magnetron valve
b) sudden deceleration of electron in x- ray tube
c) accelerated motion of charge in conducting wire
d) hot bodies and molecules

Question. why microwave use for aircraft navigation?
A) due to high wavelength
B) due to low wavelength
c) due to low frequency
d) due to their frequency modulation power

Question. which is use of microwave?
a) in treatment of cancer
b) to observe changing blood flow
c) used to kill microbes
d) studying details of atoms and molecule

Question. where do microwave fall in electromagnetic spectrum?
a) between u.v region and infrared
b) between gamma and u.v
c) between infrared and radio wave
d) between gamma and infrared

Q 2) Gamma Rays In Treatment Of Cancer
Gamma rays are used in radiotherapy to Treat cancer. They are used to spot tumors. they kill the living cells and

damage malignant tumor.

Question. what is the source of gamma rays?
a) radioactive decay of nucleus
b) accelerated motion of charges in conducting wire
c) hot bodies and molecule
d) klystron valve

Question. how is wavelength of gamma rays
a) low
b) high
c) infinite
d) zero

Question. choose the one with correct radiation order?
a) alpha>beta>gamma
b) beta>alpha>gamma
c) gamma>beta>alpha
d) gamma>alpha>beta

Question. what is other use of gamma rays?
a) used to change white topaz to blue topaz
b) used in aircraft navigation
c) used in kill microbes
d) checking fractures of bone

Q3) X- Rays
X-rays are a form of electromagnetic radiation, similar to visible light. Unlike light, however, x-rays have higher

energy and can pass through most objects, including the body. Medical x-rays are used to generate images of tissues and structures inside the body.

Question. What is the most common method of preparation of X rays ?
a) magnetron valve
b) vibration of atoms and molecules
c) bombardment of metal by high energy electrons
d) radioactive decay of nucleus

Question. which of the following set of instrument /equipment can detect X- rays
a) Photocells ,photographic film
b) Thermopiles ,bolometer
c) Photographic film ,Geiger tube
d) Geiger tube ,human eye

Question. where do X rays fall on the electromagnetic spectrum?
a) Between UV region and infrared region
b) Between gamma rays and UV region
c) Between infrared and microwaves
d) Between microwaves and radio waves

Question. what is the use of rays lying beyond X ray region in electromagnetic spectrum
a) used to kill microbes
b) used to detect heat loss in insulated systems
c) used in standard broadcast radio and television
d) used In oncology, to kill cancerous cells.

Q4). Green house effect
The greenhouse effect is a natural process that warms the Earth’s surface. When the Sun’s energy reaches the Earth’s atmosphere, some of it is reflected back to space and the rest is absorbed and re-radiated by greenhouse gases. The absorbed energy warms the atmosphere and the surface of the Earth

Question. The one which is not considered as naturally occurring greenhouse gas is
(a) methane
(b) CFCs
(c) carbon dioxide
(d) nitrous oxide

Question. Which of the following is not a use of infrared waves
a) Used in treatment for certain forms of cancer
b) in military and civilian applications include target acquisition, surveillance, night vision, homing, and tracking.
c) to observe changing blood flow in the skin
d) In imaging cameras, used to detect heat loss in insulated systems

Question. which of the following is the best method for production of infrared waves
a) bombardment of metal by high energy electrons
b) radioactive decay of nucleus
c) magnetron valve
d) vibration of atoms and molecules

Question. Wavelength of infrared radiations is
(a) shorter
(b) longer
(c) infinite
(d) zero

Q5 ) Electromagnetic (Em) Spectrum
• The electromagnetic (EM) spectrum is the range of all types of EM radiation. Radiation is energy that travels and spreads out as it goes – the visible light that comes from a lamp in your house and the radio waves that come from a radio station are two types of electromagnetic radiation. The other types of EM radiation that make up the electromagnetic spectrum are microwaves, infrared light, ultraviolet rays, X- rays and gamma rays.

Question. The classification is roughly based on?
I) Wavelength and frequency of waves.
II) Production and detection of waves.
III) The way of travelling of waves.
IV) Year discovered.

Question. Which of the following is NOT an example of EM RAYS.
I) Radiotherapy(medicine).
II) Checking fractures.
III) Sterilisation.
IV) Explosives.

Question. Identify the pair having highest frequency and highest wavelength EM WAVES.
I) UV rays and X- rays
II) Gamma rays and Microwaves.
III) Gamma rays and Radio waves.
IV) Radio waves and UV rays.

Question. What physical quantity is the same for X rays of wavelength 10-10m, red light of wavelength 6800 Ao and radiowaves of wavelength 500m?
I) Speed in vacuum (c)
II) frequency (f)
III) Scattering
IV) Energy (e)