Physics Quiz - Electromagnetic Spectrum
Questions and Answers
- 1.
A group of wavelengths (or) frequencies is known as
- A.
Group of colours
- B.
Spectrum
- C.
Colour band
- D.
None
Correct Answer
B. SpectrumExplanation
A group of wavelengths or frequencies is known as a spectrum. It refers to the range of colors or electromagnetic waves that can be seen or detected. The term spectrum is used in various fields such as physics, chemistry, and astronomy to describe the distribution of wavelengths or frequencies within a given range. It encompasses the entire range of colors or electromagnetic waves, allowing us to understand and study the properties and behavior of light and other forms of radiation.Rate this question:
-
- 2.
Electromagnetic radiations waves are:
- A.
Mechanical
- B.
Longitudinal
- C.
Transverse
- D.
Stationary
Correct Answer
C. TransverseExplanation
Electromagnetic radiation waves are transverse. This means that the oscillations of the waves occur perpendicular to the direction of wave propagation. Unlike mechanical waves, such as sound waves, electromagnetic waves do not require a medium to travel through. They can travel through vacuum as well as through different mediums, such as air or water. This transverse nature of electromagnetic waves is a fundamental characteristic that distinguishes them from other types of waves.Rate this question:
-
- 3.
Electric heater emits
- A.
IR radiations
- B.
Visible spectrum
- C.
UV rays
- D.
Micro waves
Correct Answer
A. IR radiationsExplanation
An electric heater emits infrared (IR) radiations. These radiations are a form of electromagnetic radiation that is not visible to the human eye but can be felt as heat. IR radiations have longer wavelengths than visible light and are commonly used in heating applications as they can effectively transfer heat energy to objects and surroundings.Rate this question:
-
- 4.
A device that can't absorb IR-radiations is
- A.
Flint glass
- B.
Borosilicate glass
- C.
Hard glass
- D.
Soda glass
Correct Answer
D. Soda glassExplanation
Soda glass is a type of glass that cannot absorb infrared (IR) radiations. This is because soda glass is made using sodium carbonate, which has a low refractive index and does not have the ability to absorb IR radiation. In contrast, other types of glass like flint glass, borosilicate glass, and hard glass have different compositions that allow them to absorb IR radiations to some extent. Therefore, soda glass is the correct answer as it is incapable of absorbing IR radiations.Rate this question:
-
- 5.
Prisms made up of the following is used to observe the infrared radiations
- A.
Ordinary glass
- B.
Rock salt
- C.
Epsom Salt
- D.
None
Correct Answer
B. Rock saltExplanation
Rock salt is used to make prisms that can observe infrared radiations. This is because rock salt is transparent to infrared light, allowing it to pass through without significant absorption or scattering. Ordinary glass and Epsom salt, on the other hand, are not transparent to infrared radiation and would block or distort the observation. Therefore, rock salt is the preferred material for prisms used in observing infrared radiations.Rate this question:
-
- 6.
Which of the following emits infrared radiations ?
- A.
Hot iron
- B.
Ice
- C.
Freezing mixture
- D.
Wet cloth
Correct Answer
A. Hot ironExplanation
Hot iron emits infrared radiation because it is at a high temperature. Infrared radiation is a form of electromagnetic radiation that is emitted by objects that are heated. When an object is heated, its atoms and molecules vibrate, and this vibration produces infrared radiation. Since hot iron is at a high temperature, it emits infrared radiation. Ice, freezing mixture, and wet cloth do not emit infrared radiation because they are not at a high enough temperature.Rate this question:
-
- 7.
The velocity of electromagnetic waves C=
- A.
ν/λ
- B.
νλ
- C.
λ/ν
- D.
ν+λ
Correct Answer
B. νλExplanation
The correct answer is νλ because the velocity of electromagnetic waves is equal to the product of its frequency (ν) and wavelength (λ).Rate this question:
-
- 8.
The direction of propagation of electro magnetic waves
- A.
Perpendicular to only electric field
- B.
Perpendicular to only magnetic field
- C.
Electric and magnetic fields perpendicular to each other and also perpendicular to the direction of their propagation
- D.
None
Correct Answer
C. Electric and magnetic fields perpendicular to each other and also perpendicular to the direction of their propagationExplanation
Electromagnetic waves consist of both electric and magnetic fields oscillating perpendicular to each other. These fields are also perpendicular to the direction in which the wave is propagating. This is known as transverse wave motion. The electric and magnetic fields are in phase with each other and together they propagate through space, creating the electromagnetic wave. Therefore, the correct answer is that the electric and magnetic fields are perpendicular to each other and also perpendicular to the direction of their propagation.Rate this question:
-
- 9.
The wavelength limit of visible spectrum
- A.
0.1 µm - 0.7 µm
- B.
0.4 µm - 0.7 µm
- C.
0.7 µm - 1.0 µm
- D.
0.2 µm - 0.9 µm
Correct Answer
B. 0.4 µm - 0.7 µmExplanation
The correct answer is 0.4 µm - 0.7 µm. This range represents the wavelengths of light that are visible to the human eye. Light with wavelengths shorter than 0.4 µm falls into the ultraviolet range and is not visible, while light with wavelengths longer than 0.7 µm falls into the infrared range and is also not visible. Therefore, the visible spectrum is limited to the range of 0.4 µm - 0.7 µm.Rate this question:
-
- 10.
Visible spectrum is due to :
- A.
Excitation of ē s
- B.
Deexcitation of ē s
- C.
Vibrated atoms
- D.
Rotation of atoms
Correct Answer
A. Excitation of ē sExplanation
The visible spectrum is due to the excitation of electrons. When electrons in atoms or molecules absorb energy, they move to higher energy levels. As they return to their original energy levels, they release the excess energy in the form of light. This light falls within the visible range of the electromagnetic spectrum, resulting in the colorful display of the visible spectrum.Rate this question:
-
- 11.
The charateristic colour emitted by the substance is depends on
- A.
The colour of the substance
- B.
The state of the substance
- C.
Characteristic properties of the atoms present in the substance
- D.
None
Correct Answer
C. Characteristic properties of the atoms present in the substanceExplanation
The characteristic color emitted by a substance depends on the characteristic properties of the atoms present in the substance. Different atoms have different energy levels and electron configurations, which determine the wavelengths of light that they can absorb and emit. When atoms in a substance absorb energy, their electrons move to higher energy levels. When these electrons return to their original energy levels, they release the absorbed energy in the form of light. The specific wavelengths of light emitted correspond to the energy differences between the electron energy levels, resulting in the characteristic color of the substance.Rate this question:
-
- 12.
The wavelength limit of IR is .....
- A.
0.1 µm - 0.7 µm
- B.
0.7 µm - 100 µm
- C.
10 µm - 10 m
- D.
1 m - 100 km
Correct Answer
B. 0.7 µm - 100 µmExplanation
The correct answer is 0.7 µm - 100 µm. This is because infrared (IR) radiation has wavelengths longer than those of visible light, ranging from 0.7 µm (near-infrared) to 100 µm (far-infrared). IR radiation is commonly used in various applications such as remote controls, night vision devices, and thermal imaging cameras.Rate this question:
-
- 13.
Which of the following is used to detect the IR ?
- A.
Thermometers
- B.
Thermopiles
- C.
Bolometer
- D.
All
Correct Answer
D. AllExplanation
All of the options listed (thermometers, thermopiles, and bolometers) are used to detect infrared radiation (IR). Thermometers are devices that measure temperature, and some types of thermometers can detect IR radiation. Thermopiles are specifically designed to detect IR radiation and convert it into an electrical signal. Bolometers are also used to detect IR radiation by measuring the change in resistance of a material when it absorbs IR radiation. Therefore, all of these options can be used to detect IR.Rate this question:
-
- 14.
The rays emitted by molecules when they change their state of rotational or vibrational motion are
- A.
Visible spectrum
- B.
Micro waves
- C.
Radio waves
- D.
Infrared waves
Correct Answer
D. Infrared wavesExplanation
When molecules change their state of rotational or vibrational motion, they emit rays in the form of electromagnetic radiation. Infrared waves are a type of electromagnetic radiation that has longer wavelengths than visible light. These waves are not visible to the human eye but can be detected as heat. Therefore, the correct answer is Infrared waves.Rate this question:
-
- 15.
The radiations, those find application in physio - therapy are
- A.
Visible spectrum
- B.
Micro waves
- C.
Infrared waves
- D.
Radio waves
Correct Answer
C. Infrared wavesExplanation
Infrared waves are used in physiotherapy because they have the ability to penetrate deep into the body tissues, providing therapeutic benefits. These waves generate heat, which can help in relieving pain, reducing inflammation, and promoting healing. Unlike visible light, infrared waves are not visible to the human eye but can be felt as heat. Therefore, they are commonly used in physiotherapy treatments to target specific areas of the body and provide therapeutic effects.Rate this question:
-
- 16.
The wavelength range of microwaves is
- A.
0.1 µm - 0.7 µm
- B.
10 µm - 10 m
- C.
0.7 µm - 100 µm
- D.
0.4 µm - 1 nm
Correct Answer
B. 10 µm - 10 mExplanation
Microwaves have a longer wavelength compared to other types of electromagnetic waves. The given answer, 10 µm - 10 m, represents the wavelength range of microwaves. This range includes wavelengths that are longer than those of visible light but shorter than those of radio waves. Microwaves are commonly used in communication, cooking, and radar technology due to their ability to penetrate certain materials and be easily generated and detected.Rate this question:
-
- 17.
Micro waves are produced when
- A.
Excited electrons in atoms jump back to their normal states
- B.
Electromagnetic oscillators oscillate with high frequency
- C.
Electrons are accelerated
- D.
Transitions of the electrons in atoms
Correct Answer
B. Electromagnetic oscillators oscillate with high frequencyExplanation
Micro waves are produced when electromagnetic oscillators oscillate with high frequency. This is because microwaves are a form of electromagnetic radiation, and they are generated by oscillating electromagnetic fields. As the oscillators vibrate at a high frequency, they create electromagnetic waves in the microwave range, which can then be used for various applications such as cooking or communication.Rate this question:
-
- 18.
Micro waves are used in
- A.
Radar
- B.
Telemetry
- C.
Micro wave oven
- D.
All the above
Correct Answer
D. All the aboveExplanation
Microwaves are electromagnetic waves with wavelengths ranging from 1 mm to 1 meter. They are commonly used in radar systems for detecting and tracking objects, as well as in telemetry systems for transmitting data wirelessly. Additionally, microwaves are the primary source of energy in microwave ovens, which use them to heat and cook food. Therefore, the correct answer is "all the above" as microwaves are used in radar, telemetry, and microwave ovens.Rate this question:
-
- 19.
Radio waves are produced when
- A.
Electromagnetic oscillators oscillate with low frequency
- B.
Electromagnetic oscillators oscillate with high frequency
- C.
Transition of electrons in atoms
- D.
Excited electrons in atoms jump back to their normal state
Correct Answer
A. Electromagnetic oscillators oscillate with low frequencyExplanation
Radio waves are a type of electromagnetic radiation that have a low frequency. Electromagnetic oscillators are responsible for producing electromagnetic waves, including radio waves. When these oscillators oscillate with a low frequency, they generate radio waves. Therefore, the correct answer is "electromagnetic oscillators oscillate with low frequency."Rate this question:
-
- 20.
Mapping of the radio emissions from extra-terrestrial sources is termed as
- A.
Halography
- B.
Radio-astronomy
- C.
Meteorology
- D.
None
Correct Answer
B. Radio-astronomyExplanation
Radio astronomy is the correct answer because it refers to the mapping of radio emissions from outer space. It is a scientific field that uses radio waves to study celestial objects and phenomena. By detecting and analyzing these radio signals, astronomers can gain insights into the nature and behavior of objects such as stars, galaxies, and black holes. Radio astronomy has been instrumental in discovering and studying various cosmic phenomena, including pulsars, quasars, and the cosmic microwave background radiation.Rate this question:
-
Back to top