Electromagnetic Waves Chapter-Wise Test 10

Correct answer Carries: 4.

Wrong Answer Carries: -1.

Why are infrared detectors used in Earth satellites?

The document mentions that infrared detectors are used in satellites for military purposes and to observe the growth of crops.

To detect radio waves
To measure ultraviolet radiation
To detect gamma rays
For military purposes and crop observation
4

What characteristic of visible light explains why humans evolved sensitivity to it?

Visible light corresponds to the peak wavelength distribution of solar radiation, making it the most abundant light on Earth, to which human eyes adapted for survival.

Its high frequency
Its low energy
Its long wavelength
Its abundance in solar radiation
4

What does Maxwell's displacement current ensure in the generalized Ampere's law?

The document explains that displacement current ensures consistency in the magnetic field calculation across different surfaces, resolving the contradiction in Ampere's original law.

Consistency in magnetic field calculation
Elimination of conduction current
Zero magnetic field everywhere
Constant electric field
1

In electromagnetic theory, what distinguishes the production mechanism of radio waves from that of visible light?

Radio waves are typically produced by oscillating currents in macroscopic circuits (like antennas), while visible light arises from electron transitions between energy levels within atoms.

Same production mechanism
Different scales of oscillation
Different speeds of propagation
Different media requirements
2

What type of motion of charges produces electromagnetic waves?

The document states that accelerated charges, such as those in oscillatory motion, produce electromagnetic waves, while stationary or uniformly moving charges do not.

Accelerated motion
Uniform motion
Stationary charges
Random motion
1

Which electromagnetic waves are emitted by electrons transitioning between energy levels in atoms?

The document states that visible light is emitted when electrons in atoms move from one energy level to a lower energy level.

Infrared waves
Visible light
Microwaves
Radio waves
2

What is the primary difference between various types of electromagnetic waves according to the document?

The document states that the basic difference between various types of electromagnetic waves lies in their wavelengths or frequencies, as they all travel at the same speed in vacuum.

Their wavelengths or frequencies
Their speed in vacuum
Their ability to carry energy
Their medium of propagation
1

What is a common method to detect visible light according to the document?

The document lists the human eye, photocells, and photographic film as detectors of visible light. Photocells are a common method in devices.

Thermopiles
Geiger tubes
Photocells
Receiver's aerials
3

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

Using \( v \lambda = c \), we have \( \lambda = \frac{c}{v} = \frac{3 \times 10^8}{10 \times 10^6} = 30 \, \text{m} \).

15 m
20 m
30 m
40 m
3

Why are microwaves used in radar systems for aircraft navigation?

The document explains that microwaves are suitable for radar systems because their short wavelengths allow for precise direction and ranging.

They have long wavelengths
They have short wavelengths for precision
They are absorbed by air
They travel slower than light
2

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