Electromagnetic Waves Chapter-Wise Test 12

Correct answer Carries: 4.

Wrong Answer Carries: -1.

Why are X-rays used as a diagnostic tool in medicine?

The document explains that X-rays can penetrate tissues and are used to image internal structures, making them effective for diagnosis.

They heat tissues
They emit visible light
They kill germs
They penetrate tissues for imaging
4

In electromagnetic wave propagation, what ensures energy conservation during wave travel?

The energy in an electromagnetic wave is carried by both electric and magnetic fields, with the total energy flux described by the Poynting vector, ensuring conservation during propagation.

Static fields
Medium interactions
Poynting vector
Frequency variation
3

What characteristic of radio waves enables their use in broadcasting over large areas?

Radio waves have long wavelengths, allowing them to diffract around obstacles and reflect off the ionosphere, facilitating wide-area coverage for broadcasting.

High frequency
Long wavelength
Short penetration
Visible spectrum
2

Why are gamma rays used in sterilization of medical equipment?

Gamma rays penetrate deeply and have high energy, enabling them to kill bacteria and pathogens effectively without leaving chemical residues, ideal for sterilizing medical equipment.

Low energy
Visible emission
Thermal heating
Deep penetration
4

Which scientist succeeded in transmitting electromagnetic waves over long distances, marking the beginning of communication technology?

The document mentions that Guglielmo Marconi transmitted electromagnetic waves over many kilometers, initiating communication technology.

Heinrich Rudolf Hertz
Guglielmo Marconi
Jagdish Chandra Bose
James Clerk Maxwell
2

Which type of electromagnetic waves are produced by radioactive decay of the nucleus?

The document states that gamma rays are produced in nuclear reactions and emitted by radioactive nuclei.

X-rays
Gamma rays
Ultraviolet rays
Infrared waves
2

What is the approximate wavelength range of visible light as per the document?

The document states that visible light ranges from about \( 700 \, \text{nm} \) to \( 400 \, \text{nm} \).

\( 1 \, \text{mm} \) to \( 700 \, \text{nm} \)
\( 400 \, \text{nm} \) to \( 0.6 \, \text{nm} \)
\( 10^{-10} \, \text{m} \) to \( 10^{-14} \, \text{m} \)
\( 700 \, \text{nm} \) to \( 400 \, \text{nm} \)
4

In the electromagnetic spectrum, what characteristic of UV rays makes them harmful to human tissue?

UV rays have higher energy due to their shorter wavelengths (higher frequencies), which can damage living tissues by breaking molecular bonds, leading to effects like skin cancer.

Their long wavelength
Their high energy
Their low frequency
Their thermal properties
2

An electromagnetic wave has an angular frequency \( \omega = 6 \times 10^{11} \, \text{rad/s} \). What is its frequency in Hz?

Frequency \( v = \frac{\omega}{2\pi} \). Given \( \omega = 6 \times 10^{11} \, \text{rad/s} \), \( v = \frac{6 \times 10^{11}}{2 \pi} \approx 9.55 \times 10^{10} \, \text{Hz} \).

\( 3 \times 10^{10} \, \text{Hz} \)
\( 9.55 \times 10^{10} \, \text{Hz} \)
\( 1.2 \times 10^{11} \, \text{Hz} \)
\( 1.5 \times 10^{11} \, \text{Hz} \)
2

What does Gauss's Law for electricity describe in Maxwell's equations?

Gauss's Law for electricity states that the electric flux through a closed surface is proportional to the charge enclosed, given by \( \oint \mathbf{E} \cdot \mathrm{d} \mathbf{A} = \frac{Q}{\varepsilon_0} \).

Electric flux proportional to enclosed charge
Magnetic flux proportional to current
Induction of magnetic fields
No magnetic monopoles
1

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