Q.1 Which of the following is a transverse wave?
Sound wave
Light wave
Longitudinal water wave
Shock wave
Explanation - Electromagnetic waves, including light, are transverse waves because their electric and magnetic fields oscillate perpendicular to the direction of wave propagation.
Correct answer is: Light wave
Q.2 Electromagnetic waves do not require a medium for propagation because they are:
Transverse mechanical waves
Longitudinal mechanical waves
Self-propagating electric and magnetic fields
Sound waves in vacuum
Explanation - Electromagnetic waves consist of oscillating electric and magnetic fields that sustain each other, allowing propagation through vacuum.
Correct answer is: Self-propagating electric and magnetic fields
Q.3 The speed of electromagnetic waves in vacuum is approximately:
3 × 10^6 m/s
3 × 10^8 m/s
3 × 10^5 m/s
3 × 10^10 m/s
Explanation - The speed of all electromagnetic waves in vacuum is the speed of light, which is 3 × 10^8 meters per second.
Correct answer is: 3 × 10^8 m/s
Q.4 Which of the following has the shortest wavelength?
Radio waves
Microwaves
X-rays
Infrared waves
Explanation - X-rays have much shorter wavelengths compared to radio, microwaves, and infrared waves, making them highly penetrating.
Correct answer is: X-rays
Q.5 Which electromagnetic waves are used for cooking food in microwave ovens?
Radio waves
Microwaves
Infrared waves
Ultraviolet waves
Explanation - Microwaves penetrate food and cause water molecules to vibrate, generating heat and cooking the food.
Correct answer is: Microwaves
Q.6 What property of electromagnetic waves allows them to carry energy without a medium?
Amplitude
Frequency
Mutual induction of E and B fields
Wavelength
Explanation - The changing electric field produces a magnetic field and vice versa, allowing electromagnetic waves to propagate energy in vacuum.
Correct answer is: Mutual induction of E and B fields
Q.7 Which part of the electromagnetic spectrum is used in medical imaging to view bones?
Radio waves
X-rays
Ultraviolet rays
Gamma rays
Explanation - X-rays can penetrate soft tissue but are absorbed by denser materials like bones, creating images for diagnosis.
Correct answer is: X-rays
Q.8 Frequency of electromagnetic waves is directly proportional to:
Wavelength
Energy
Amplitude
Speed in vacuum
Explanation - The energy of a photon is E = hν, showing that higher frequency corresponds to higher energy.
Correct answer is: Energy
Q.9 Electromagnetic waves with frequency just above visible light are:
Radio waves
Microwaves
Ultraviolet waves
Infrared waves
Explanation - Ultraviolet waves lie immediately beyond the violet end of the visible spectrum, having higher frequencies than visible light.
Correct answer is: Ultraviolet waves
Q.10 The component of an electromagnetic wave that oscillates perpendicular to the direction of propagation is the:
Electric field only
Magnetic field only
Electric and Magnetic fields
Sound wave
Explanation - In an EM wave, the electric field and magnetic field are perpendicular to each other and to the direction of wave propagation.
Correct answer is: Electric and Magnetic fields
Q.11 Which electromagnetic waves are used in remote controls?
Infrared waves
Ultraviolet waves
X-rays
Gamma rays
Explanation - Infrared waves are used in remote controls because they can transmit signals over short distances without visible light interference.
Correct answer is: Infrared waves
Q.12 Which EM waves are known for their ionizing ability and are used in sterilization?
Radio waves
Microwaves
Ultraviolet waves
Infrared waves
Explanation - Ultraviolet waves have enough energy to break chemical bonds in microorganisms, making them useful for sterilization.
Correct answer is: Ultraviolet waves
Q.13 The energy of an electromagnetic wave is transported by:
Magnetic field only
Electric field only
Both electric and magnetic fields
Medium particles
Explanation - Energy in EM waves is carried by both the oscillating electric and magnetic fields, as described by the Poynting vector.
Correct answer is: Both electric and magnetic fields
Q.14 The part of the EM spectrum that can cause skin tanning is:
Infrared rays
Ultraviolet rays
X-rays
Microwaves
Explanation - UV rays have higher energy than visible light, causing chemical changes in skin pigment and resulting in tanning.
Correct answer is: Ultraviolet rays
Q.15 Electromagnetic waves in a vacuum propagate at the speed:
Dependent on frequency
Dependent on wavelength
Independent of wavelength or frequency
Zero
Explanation - All EM waves propagate in vacuum at the same speed, c ≈ 3 × 10^8 m/s, regardless of their frequency or wavelength.
Correct answer is: Independent of wavelength or frequency
Q.16 Which part of the EM spectrum is used in night vision devices?
Infrared waves
Ultraviolet waves
X-rays
Gamma rays
Explanation - Infrared waves emitted by warm objects can be detected and converted into visible images in night vision devices.
Correct answer is: Infrared waves
Q.17 Gamma rays differ from X-rays mainly in:
Speed
Source and energy
Wavelength in air
Medium required for propagation
Explanation - Gamma rays originate from nuclear transitions and generally have higher energy than X-rays, which originate from electron transitions.
Correct answer is: Source and energy
Q.18 Which EM waves are used for long-distance communication via satellites?
Gamma rays
X-rays
Microwaves
Infrared rays
Explanation - Microwaves can penetrate the atmosphere and carry signals over long distances, making them ideal for satellite communication.
Correct answer is: Microwaves
Q.19 Electromagnetic waves carry energy and:
Momentum only
Momentum and angular momentum
Pressure only
No momentum
Explanation - EM waves carry both linear momentum and angular momentum, which can exert pressure on objects (radiation pressure).
Correct answer is: Momentum and angular momentum
Q.20 Which EM waves are used in MRI machines indirectly via radio frequency pulses?
Microwaves
Radio waves
X-rays
Gamma rays
Explanation - MRI uses strong magnetic fields and radio frequency pulses to align and detect the spin of nuclei in the body.
Correct answer is: Radio waves
Q.21 The range of visible light in the EM spectrum is approximately:
400–700 nm
100–400 nm
700–1000 nm
10–100 nm
Explanation - Visible light spans wavelengths from about 400 nm (violet) to 700 nm (red).
Correct answer is: 400–700 nm
Q.22 The term 'electromagnetic radiation' refers to:
Sound waves traveling in a medium
Oscillating electric and magnetic fields propagating through space
Mechanical waves in solids
Magnetic fields only
Explanation - Electromagnetic radiation is the propagation of energy via mutually perpendicular electric and magnetic fields through space.
Correct answer is: Oscillating electric and magnetic fields propagating through space
Q.23 Which EM waves are used for sterilizing surgical instruments in hospitals?
Microwaves
Ultraviolet waves
Radio waves
Infrared waves
Explanation - UV radiation can kill bacteria and viruses by destroying their DNA, making it useful for sterilization.
Correct answer is: Ultraviolet waves
Q.24 In an EM wave, the direction of the magnetic field is:
Parallel to the electric field
Perpendicular to both the electric field and propagation direction
Along the direction of propagation
Opposite to the electric field
Explanation - In a transverse EM wave, the electric field, magnetic field, and propagation direction are mutually perpendicular.
Correct answer is: Perpendicular to both the electric field and propagation direction
Q.25 Which EM waves are used in fiber-optic communication?
Visible light
Infrared waves
Microwaves
Radio waves
Explanation - Infrared light is commonly used in optical fibers because it suffers less attenuation and can travel long distances efficiently.
Correct answer is: Infrared waves