InterviewSolution
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InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 201. |
What are electric and magnetic fields and what are their sources? |
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Answer» a. Electric field is the force experienced by a test charge in presence of the given charge at the given distance from it. b. A magnetic field is produced around a magnet or around a current carrying conductor. |
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| 202. |
The electric field intensity produced by the radiations coming from 100 W bulb at a 3 m distance is E. The electric field intensity produced by the radiations coming from 50 W bulb at the same distance is(a) E/2.(b) 2E.(c) E/√2.(d) √2E. |
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Answer» The electric field intensity is √2E. |
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| 203. |
Light with an energy flux of 20 W/cm2 falls on a non-reflecting surface at normal incidence. If the surface has an area of 30 cm2. the total momentum delivered (for complete absorption) during 30 minutes is(a) 36 × 10–5 kg m/s.(b) 36 × 10–4 kg m/s.(c) 108 × 104 kg m/s.(d) 1.08 × 107 kg m/s. |
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Answer» (b) 36 × 10–4 kg m/s. |
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| 204. |
What is meant by Fraunhofer lines? |
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Answer» When the spectrum obtained from the Sun is examined, it consists of large number of dark lines (line absorption spectrum). These dark lines in the solar spectrum are known as Fraunhofer lines. |
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| 205. |
Represent electric and magnetic fields of an electromagnetic wave mathematically by suitable wave equations. Express c in terms of µ0 and ɛo. |
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Answer» Mathematically, for a wave of angular frequency ω wavelength propagating along z-direction we can write Ex and By as follows : Ex = E0 sin (kz– ωt ) and By = B0 sin (kz– ωt ), where ω is the angular frequency and k = 2π/λ is the magnitude of the wave vector (or propagation vector) and ω = ck, where, c = 1/ √µ0 ɛo = speed of light in vacuum. The amplitude of the electric and magnetic field are related as B0 = E0/c. |
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| 206. |
If E is an electric field and vector B is the magnetic induction, then the energy flow per unit area per unit time in an electromagnetic field is given by(A) \(\frac{1}{\mu_0}\) \(\overset\rightarrow{E}\times\overset\rightarrow{B}\)(B) \(\overset\rightarrow{E}.\overset\rightarrow{B}\)(C) E2 + B2(D) \(\frac{E}{B}\) |
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Answer» Correct option is: (A) \(\frac{1}{\mu_0}\) \(\overset\rightarrow{E}\times\overset\rightarrow{B}\) |
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| 207. |
Which of the following type of radiations are radiated by an oscillating electric charge?(A) Electric (B) Magnetic (C) Thermoelectric (D) Electromagnetic |
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Answer» Correct option is: (D) Electromagnetic |
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| 208. |
State uses and limitations of frequency modulation. |
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Answer» 1. Frequency modulation (FM) is more complex as compared to amplitude modulation and, therefore is more difficult to implement. 2. However, its main advantage is that it reproduces the original signal closely and is less susceptible to noise. 3. This modulation is used for high quality broadcast transmission. |
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| 209. |
State advantages and disadvantages of amplitude modulation. |
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Answer» Advantages: 1. It is simple to implement. 2. It has large range. 3. It is cheaper. Disadvantages: 1. It is not very efficient as far as power usage is concerned. 2. It is prone to noise. 3. The reproduced signal may not exactly match the original signal. In spite of this, these are used for commercial broadcasting in the long, medium and short wave bands. |
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| 210. |
How does the effective power radiated by an antenna vary with wavelength? |
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Answer» 1. To transmit a signal, an antenna or an aerial is needed. 2. Power radiated from a linear antenna of length l is, P ∝ (l/λ)2 where, λ is the wavelength of the signal. |
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| 211. |
What is demodulation? |
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Answer» The process of regaining signal from a modulated wave is called demodulation. This is the reverse process of modulation. |
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| 212. |
What type of modulation is required for television broadcast? |
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Answer» Amplitude modulation is required for television broadcast. |
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| 213. |
Why are microwaves considered suitable for radar systems used in aircraft navigation ? |
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Answer» Due to their short wavelength. |
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| 214. |
To which part of the electromagnetic spectrum does a wave of frequency 3 x 1013 Hz belong ? |
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Answer» Infrared region. |
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| 215. |
Electromagnetic waves are ………… |
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Answer» Electromagnetic waves are Transverse in nature. |
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| 216. |
Electromagnetic waves are produced by (a) Atoms and molecules in an electrical discharge (b) Electric device (c) Accelerated charges (d) Molecules of hot bodies |
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Answer» Correct answer is (c) Accelerated charges. |
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| 217. |
In electromagnetic waves, angle between electric and magnetic field vectors is…… |
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Answer» In electromagnetic waves, angle between electric and magnetic field vectors is 90°. |
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| 218. |
The electromagnetic waves travel in vacuum or free space with a velocity of …… |
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Answer» The electromagnetic waves travel in vacuum or free space with a velocity of 3 x 108 m s-1 |
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| 219. |
Electromagnetic disturbance can be propagated through space …… |
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Answer» Electromagnetic disturbance can be propagated through space without the help of material medium. |
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| 220. |
In an electromagnetic wave in free space the rms value of the electric field is 3 V m-1. The peak value of the magnetic field is ……….(a) 1.414 x 10-8 T (b) 1.0 x 10-8 T (c) 2.828 x 10-8 T (d) 2.0 x 10-8 T |
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Answer» Correct answer is (a) 1.414 x 10-8 T |
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