Electromagnetic Waves Chapter-Wise Test 22

Correct answer Carries: 4.

Wrong Answer Carries: -1.

What explains the ability of electromagnetic waves to exhibit polarization?

Electromagnetic waves are transverse, meaning their electric and magnetic fields oscillate perpendicular to the direction of propagation, allowing the orientation of these fields to be manipulated for polarization.

Longitudinal nature
Medium dependence
Frequency variation
Transverse nature
4

Why are X-rays used in crystallography to study atomic structures?

X-rays have wavelengths comparable to atomic spacings, allowing them to diffract off crystal lattices and produce interference patterns that reveal atomic arrangements.

High penetration
Thermal effects
Comparable wavelengths
Visible spectrum
3

An electromagnetic wave has a magnetic field amplitude of \( B_0 = 6 \times 10^{-8} \, \text{T} \). What is the electric field amplitude? (Given \( c = 3 \times 10^8 \, \text{m/s} \))

Using \( E_0 = B_0 c \), we have \( E_0 = (6 \times 10^{-8}) \times (3 \times 10^8) = 18 \, \text{V/m} \).

12 V/m
15 V/m
16 V/m
18 V/m
4

What distinguishes the mechanism of energy transfer in electromagnetic waves from that in mechanical waves?

Electromagnetic waves transfer energy via oscillating electric and magnetic fields without a medium, while mechanical waves require a medium and transfer energy through particle vibrations.

Same mechanism
No medium for electromagnetic waves
Electromagnetic waves need particles
Mechanical waves use fields
2

Which electromagnetic waves are used in remote switches of household electronic systems?

Infrared waves are widely used in remote switches for devices like TVs and hi-fi systems, as mentioned in the document.

Radio waves
Infrared waves
Microwaves
Ultraviolet waves
2

What is the typical wavelength range of radio waves used in television communication?

The document mentions that TV waves range from \( 54 \, \text{MHz} \) to \( 890 \, \text{MHz} \). Using \( \lambda = \frac{c}{v} \), this corresponds to wavelengths from about \( 0.34 \, \text{m} \) to \( 5.56 \, \text{m} \). A simpler range based on frequency is used here.

\( 1 \, \text{mm} \) to \( 700 \, \text{nm} \)
Corresponding to \( 54 \, \text{MHz} \) to \( 890 \, \text{MHz} \)
\( 400 \, \text{nm} \) to \( 0.6 \, \text{nm} \)
\( < 10^{-14} \, \text{m} \)
2

What is one precaution welders take to protect their eyes from UV radiation?

The document mentions that welders wear special glass goggles or face masks to protect their eyes from the large amounts of UV radiation produced by welding arcs.

Wear ordinary sunglasses
Use visible light filters
Avoid using any protection
Wear special glass goggles
4

An electromagnetic wave in vacuum has a frequency of \( 40 \, \text{MHz} \). What is its wavelength? (Given \( c = 3 \times 10^8 \, \text{m/s} \))

Using \( v \lambda = c \), we have \( \lambda = \frac{c}{v} = \frac{3 \times 10^8}{40 \times 10^6} = 7.5 \, \text{m} \).

5 m
7.5 m
10 m
12.5 m
2

Why are gamma rays more hazardous than visible light when interacting with human tissue?

Gamma rays have much higher energy due to their extremely short wavelengths, enabling them to penetrate tissues and cause ionization, which damages cells, unlike visible light.

Lower frequency
Visible spectrum
Thermal effects
Higher energy
4

What makes electromagnetic waves different from other waves discussed in the document?

The document notes that electromagnetic waves differ from other waves because they involve no material medium for propagation—they are oscillations of electric and magnetic fields.

They have higher frequencies
They are always visible
They travel slower
They require no material medium
4

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