Case Study Questions Class 12 Physics Electromagnetic Waves

Case Study Questions Class 12 Physics Chapter 8 Electromagnetic Waves

CBSE Class 12 Case Study Questions Physics Electromagnetic Waves. Term 2 Important Case Study Questions for Class 12 Board Exam Students. Here we have arranged some Important Case Base Questions for students who are searching for Paragraph Based Questions Electromagnetic Waves.

At Case Study Questions there will given a Paragraph. In where some Important Questions will made on that respective Case Based Study. There will various types of marks will given 1 marks, 2 marks, 3 marks, 4 marks.

CBSE Case Study Questions Class 12 Physics Electromagnetic Waves

Case study 1:

According to Maxwell’s electromagnetic equations it has been proved that electric and magnetic field vectors are perpendicular to each other and also perpendicular to the direction of propagation as shown in the figure below. If Ex is the electric field along X axis, then Bywill be the direction of magnetic field along y axis and both which are perpendicular to the z axis showing direction of propagation. The light waves are also the electromagnetic waves and may travels through vacuum also. So, we can find the velocity of a light traveling through the material medium having permittivity € and magnetic permeability u as V = 1/√ɛμ

In this way, we proved that velocity of light also depends on the electrical and magnetic properties of that medium through which it is traveling. The velocity of light which is constant everywhere is having value as 3*108m/s.The most technological importance of electromagnetic waves is that they are having strong capacity to take energy from one place to another place. The best examples are radio waves, TV signals which also carry energy from their broadcasting stations. Also, life is possible on the earth only because of the sunlight coming from the sun to the earth which also carry energy and it is nothing but the electromagnetic waves. Due to which electromagnetic waves are considered as the transverse waves.

Q 1.) The ratio of relative permittivity of the medium to the permittivity of vacuum is called as______.

a) permeability

b) permittivity of free space

c) dielectric constant of the medium

d) electric intensity

Q 2.) Who showed that electromagnetic waves can be polarised?

a) Maxwell

b) Hertz

c) Ampere

d) Michelson and Morley

Q 3.) The pressure exerted by the electromagnetic waves is called as

a) light pressure

b) electric pressure

c) magnetic pressure

d) radiation pressure

Q 4.) What is the relationship between magnitude of magnetic field and electric field in case of electromagnetic waves from the Maxwell’s equations?

Q 5.) What is mean by the permittivity and permeability of the medium?

Answers key:

Q 1.) c) dielectric constant of the medium

Q 2.) b) Hertz

Q 3.) d) radiation pressure

Q 4.) From Maxwell’s equations, the relationship between magnitude of magnetic field and electric field is given as Bo = (Eo/c)

Q 5.) Permittivity of the medium is nothing but the ability of that medium to store electric potential energy in that medium.

While permeability of the medium is also the ability of the medium to allow the number of magnetic field lines through it.

Case study 2:

The electromagnetic spectrum consists of visible light, x- rays, gamma rays, microwaves, ultraviolet rays, radio waves and infrared waves. The waves used in radio and television communication are the radio waves having frequency range 500 kHz to 1000MHz.  In the ultrahigh frequency bands cellular phone uses the radio waves to transmit the voice. Microwaves are the waves having short wavelength. In aircraft navigation, for the radar system microwaves are used due to their short wavelength. Infrared waves are also called as heat waves. Infrared radiation has most importance in maintaining earth’s surface temperature through greenhouse effect. The infrared waves have vast application in real life such as infrared detectors are used for military purposes and also to see the growth of crops.  The waves which are visible to human eye are the visible rays. Visible rays are having frequency range as 4*1014 Hz to 7*1014 Hz. The huge source of ultraviolet light is the sun. Ultraviolet rays have wavelength range from 4*10-7m to 6*10-10m. X-rays are the rays having most importance in medical applications which are having wavelength range 10nm to 10-4 nm. X-rays are used to destroy the living tissue and organisms in medical field. Then gamma rays are the rays having wavelength range as 10-10m to 10-14m which are the high frequency radiations mostly produced in nuclear reactions. Gamma rays are also used to destroy cancer cells in medical field.

Q 1.) The TV waves range from _____ which are the radio waves.

a) 54Hz to 890Hz

b) 54 MHz to 890 MHz

c) 500 kHz to 1000 MHz

d) 1000 Hz to 1000 KHz

Q 2.) The domestic application of microwaves used is____

a) electric induction

b) water heater

c) TV

d) microwave oven

Q 3.) The part of the electromagnetic spectrum which is detected by human eye is having wavelength range as

a) 900 – 400 nm

b) 200 – 400 mm

c) 700 – 400 mm

d) 700 – 400 nm

Q 4.) Why infrared waves are also called as heat waves?

Q 5.) How ozone layer in atmosphere plays a protective role?

Answer key:

Q 1.) b) 54MHz to 890 MHz

Q 2.) d) microwave oven

Q 3.) d) 700 – 400 nm

Q 4.) Infrared red waves are the waves which are having frequency lower than the frequency of visible light range. This infrared wave causes to vibrate the electrons, whole atom or molecules also of that material. Due to such increased vibrations the internal energy of the material gets increased and thereby increase in the temperature of the material and heat is generated. Because of this reason infrared waves are also called as the heat waves.

Q 5.) The very harmful ultraviolet rays coming from sun are absorbed by the ozone layer in the atmosphere which is at an altitude of 40 – 50 km from the earths surface. And due to which very less ultraviolet light rays from the sun reach to the earth. Ultraviolet rays are very harmful to human which may causes skin cancer. In this way, ozone layer in the atmosphere plays a very protective role.

Updated: March 18, 2022 — 12:21 pm

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