What is the purpose of a waveguide in an electromagnetic system?
A Amplify signals
B Reflect signals
C Transmit signals
D Absorb signals
A waveguide is used to direct electromagnetic waves in a specific direction, ensuring minimal signal loss. They are commonly used in high-frequency communication systems to transmit microwaves or radio waves.
Which type of electromagnetic wave is primarily used in radar systems?
A Microwaves
B Radio waves
C X-rays
D Gamma rays
Microwaves are commonly used in radar systems due to their ability to penetrate through the atmosphere and provide high–resolution imaging. They are also used for communication in satellites and aviation systems.
What does electromagnetic interference (EMI) typically cause in electronic circuits?
A Signal enhancement
B Increased frequency
C Reduced current
D Signal distortion
Electromagnetic interference (EMI) can disrupt electronic circuits by introducing unwanted electromagnetic energy into the system, leading to signal distortion, noise, or malfunction in devices such as computers and radios.
What is the effect of a dielectric material between the plates of a capacitor?
A Decreases capacitance
B Increases capacitance
C Increases resistance
D Decreases resistance
A dielectric material between the plates of a capacitor increases its capacitance by reducing the electric field between the plates, allowing the capacitor to store more charge at a given voltage.
What happens when an electromagnetic wave moves from a low–density medium to a high–density medium?
A Wave is absorbed
B Speed increases
C Speed decreases
D No change in speed
When an electromagnetic wave enters a medium with higher refractive index (higher density), its speed decreases, and the wave bends toward the normal. This is explained by Snell’s law of refraction.
What does a low–pass filter allow in an electromagnetic system?
A High–frequency signals
B All signals
C Only noise
D Low–frequency signals
A low–pass filter allows low–frequency signals to pass through while attenuating higher frequencies. It is commonly used in communication systems to block unwanted high–frequency noise.
What is the basic principle behind electromagnetic wave transmission?
A Electric and magnetic field interaction
B Magnetic induction
C Waveguiding
D Electric field variation
Electromagnetic wave transmission relies on the interaction between oscillating electric and magnetic fields. These fields propagate through space and carry energy without requiring a medium, such as in the case of light traveling through a vacuum.
Which of the following affects the propagation speed of electromagnetic waves in a material?
A Electric conductivity
B Magnetic permeability
C Both B and C
D Electric permittivity
The propagation speed of electromagnetic waves in a material is influenced by its magnetic permeability and electric permittivity. Their product determines the speed at which the wave propagates through the medium.
What type of waves are used for communication in optical fibers?
A Radio waves
B Light waves
C Microwaves
D X–rays
Optical fibers use light waves, typically in the infrared or visible spectrum, to transmit data. Light is guided through the fiber by total internal reflection, allowing for high–speed and high–capacity communication over long distances.
What is the primary function of shielding in electromagnetic systems?
A Block unwanted signals
B Increase signal strength
C Absorb radiation
D Reflect radiation
Shielding is used to prevent electromagnetic interference (EMI) by blocking unwanted external signals from entering sensitive electronic devices or preventing the device’s signals from leaking out.
What does a waveguide typically consist of?
A A dielectric material
B A conductor and insulator
C A hollow metallic tube
D A solid dielectric core
A waveguide is typically a hollow metallic structure that directs the flow of electromagnetic waves. It is most effective for high–frequency signals such as microwaves and is used to prevent signal loss and control wave propagation.
What happens when an electromagnetic wave passes through a medium with a lower refractive index?
A Speed decreases
B No change in speed
C Wave disappears
D Speed increases
When an electromagnetic wave moves from a medium with a higher refractive index to one with a lower refractive index, its speed increases, and the wave bends away from the normal. This is also described by Snell’s law.
Which of the following is a common source of electromagnetic interference (EMI)?
A Motors
B Batteries
C Diodes
D Capacitors
Motors, especially those with brushes, are common sources of electromagnetic interference (EMI). They generate fluctuating magnetic fields that can disrupt nearby electronic circuits and systems, affecting signal quality.
What happens when an electromagnetic wave is incident at the critical angle on a boundary between two media?
A Refraction
B Diffraction
C Total reflection
D Polarization
When an electromagnetic wave strikes the boundary between two media at the critical angle, total internal reflection occurs. The wave is completely reflected back into the first medium, with no transmission through the boundary.
How does an increase in frequency affect the wavelength of an electromagnetic wave in a given medium?
A Increases wavelength
B Decreases wavelength
C No change
D Increases amplitude
As the frequency of an electromagnetic wave increases, its wavelength decreases, according to the relationship c=λ×f, where c is the speed of light, λ is the wavelength, and f is the frequency.