Radiation

Radiation is the transfer of heat energy through:
a) Conduction
b) Convection
c) Direct contact
d) Electromagnetic waves
✅ d) Electromagnetic waves
Explanation: Radiation transfers energy via EM waves and doesn't need a medium.
Which of the following can travel through a vacuum?
a) Sound waves
b) Convection currents
c) Radiation
d) Heat via conduction
✅ c) Radiation
Explanation: Only radiation can travel through vacuum (e.g., sunlight to Earth).
Which of the following is NOT a form of electromagnetic radiation?
a) X-rays
b) Gamma rays
c) Sound waves
d) Microwaves
✅ c) Sound waves
Explanation: Sound is a mechanical wave, not EM radiation.
Which radiation has the highest energy?
a) Ultraviolet
b) Infrared
c) Gamma rays
d) Radio waves
✅ c) Gamma rays
Explanation: Gamma rays are most energetic and highly penetrating.
Which radiation causes sunburn and skin cancer?
a) Radio waves
b) Ultraviolet rays
c) Infrared rays
d) Microwaves
✅ b) Ultraviolet rays
Explanation: UV rays are harmful to skin and may damage DNA.
Ionizing radiation includes:
a) Infrared and radio waves
b) Gamma rays and X-rays
c) Microwaves
d) Visible light
✅ b) Gamma rays and X-rays
Explanation: Ionizing radiation carries enough energy to remove electrons from atoms.
Which device detects radiation?
a) Thermometer
b) Geiger-Muller counter
c) Barometer
d) Calorimeter
✅ b) Geiger-Muller counter
Explanation: It detects ionizing radiation like alpha, beta, gamma.
Which of the following radiations is used in microwave ovens?
a) Ultraviolet
b) Infrared
c) Microwaves
d) Gamma rays
✅ c) Microwaves
Explanation: Microwaves excite water molecules to heat food.
The visible part of the EM spectrum lies between:
a) Infrared and ultraviolet
b) Radio and infrared
c) X-ray and gamma
d) UV and X-ray
✅ a) Infrared and ultraviolet
Explanation: Visible light lies in between ~400–700 nm.
Which radiation is used in remote controls?
a) Gamma
b) UV
c) Infrared
d) Visible
✅ c) Infrared
Explanation: IR signals are used in TV remotes.

Predicted and Advanced Questions

Radiation that helps in Vitamin D synthesis:
a) Infrared
b) UV-B
c) UV-C
d) X-rays
✅ b) UV-B
Explanation: Moderate exposure to UV-B synthesizes Vitamin D in the skin.
What is the unit of radiation dose?
a) Watt
b) Gray (Gy)
c) Kelvin
d) Pascal
✅ b) Gray (Gy)
Explanation: Gy is SI unit of absorbed radiation dose.
Which part of the EM spectrum is used in medical imaging?
a) UV
b) X-rays
c) Infrared
d) Radio waves
✅ b) X-rays
Explanation: X-rays can penetrate soft tissues and help visualize bones.
Alpha particles are:
a) High-energy electrons
b) Neutrons
c) Helium nuclei
d) Protons only
✅ c) Helium nuclei
Explanation: Alpha particles = 2 protons + 2 neutrons (He²⁺).
Which radiation is used in night vision devices?
a) UV
b) Infrared
c) Visible
d) Microwaves
✅ b) Infrared
Explanation: IR detection is used in thermal imaging/night vision.
The radiation most blocked by the ozone layer is:
a) UV-A
b) UV-B
c) UV-C
d) Infrared
✅ c) UV-C
Explanation: Ozone layer absorbs highly dangerous UV-C radiation.
Which of the following has the longest wavelength?
a) Gamma rays
b) X-rays
c) Radio waves
d) Ultraviolet rays
✅ c) Radio waves
Explanation: Longer wavelength → lower energy → radio waves.
Radiation therapy for cancer typically uses:
a) Alpha particles
b) Beta rays
c) Gamma rays
d) Microwaves
✅ c) Gamma rays
Explanation: Gamma rays kill cancerous cells by damaging DNA.
Which of these is non-ionizing radiation?
a) X-rays
b) Gamma rays
c) UV-C rays
d) Visible light
✅ d) Visible light
Explanation: Non-ionizing means not strong enough to remove electrons.
Which color in visible light carries most energy?
a) Red
b) Yellow
c) Green
d) Violet
✅ d) Violet
Explanation: Shorter wavelength → higher frequency → more energy.

Mixed Applications & PYQ-style

Radiation is transferred from Sun to Earth by:
a) Conduction
b) Convection
c) Radiation
d) All three
✅ c) Radiation
The greenhouse effect is mainly caused by:
a) UV radiation
b) Infrared radiation trapped
c) X-rays
d) Visible light reflection
✅ b) Infrared radiation trapped
Explanation: Infrared heat is absorbed and re-emitted by greenhouse gases.
Which radiation is used in satellite communication?
a) X-rays
b) Radio waves
c) Gamma rays
d) UV rays
✅ b) Radio waves
Which radiation is mostly used in lasers?
a) Gamma
b) Infrared
c) UV
d) X-rays
✅ b) Infrared
The term “black body radiation” is related to:
a) Magnetic fields
b) Heat loss by conduction
c) Radiation by a perfect emitter
d) Reflection of light
✅ c) Radiation by a perfect emitter
Which law explains the distribution of energy in blackbody radiation?
a) Stefan’s law
b) Newton’s law
c) Planck’s law
d) Ohm’s law
✅ c) Planck’s law
Which instrument measures solar radiation?
a) Anemometer
b) Pyranometer
c) Hydrometer
d) Spectrometer
✅ b) Pyranometer
Electromagnetic radiation is a combination of:
a) Sound and magnetic waves
b) Electric and magnetic waves
c) Heat and sound
d) None
✅ b) Electric and magnetic waves
Which of the following radiations can be harmful to DNA?
a) Gamma rays
b) X-rays
c) UV rays
d) All of the above
✅ d) All of the above
Which natural phenomenon proves light is an electromagnetic wave?
a) Reflection
b) Refraction
c) Interference
d) Polarization
✅ d) Polarization

Advanced & Higher-order MCQs

Which principle is used in thermal scanners?
a) X-ray reflection
b) Infrared radiation
c) Sound wave reflection
d) UV rays
✅ b) Infrared radiation
Which of these is used to sterilize medical equipment?
a) Radio waves
b) Microwaves
c) Gamma radiation
d) Infrared
✅ c) Gamma radiation
Which of these does NOT belong to EM spectrum?
a) UV rays
b) X-rays
c) Beta particles
d) Radio waves
✅ c) Beta particles
Radiowaves are mainly produced by:
a) Atomic nucleus
b) Oscillating circuits
c) High-frequency UV
d) Infrared lasers
✅ b) Oscillating circuits
The unit “Sievert” measures:
a) Frequency
b) Radiation dose (biological effect)
c) Sound pressure
d) Current
✅ b) Radiation dose (biological effect)
Microwaves lie between:
a) X-ray and UV
b) Infrared and radio waves
c) UV and visible
d) Gamma and X-ray
✅ b) Infrared and radio waves
Which rays are used to treat cancer via internal radiation?
a) Alpha
b) X-rays
c) Gamma
d) UV
✅ c) Gamma
Ozone absorbs radiation in which range?
a) Microwave
b) UV
c) X-ray
d) IR
✅ b) UV
What is the wavelength range of visible light?
a) 200–300 nm
b) 700–800 nm
c) 400–700 nm
d) 100–300 nm
✅ c) 400–700 nm
Radiations emitted by radioactive substances are:
a) Only alpha
b) Only gamma
c) Alpha, beta, gamma
d) Only beta
✅ c) Alpha, beta, gamma
Which of these EM waves are used for cooking?
a) UV
b) Microwave
c) IR
d) X-rays
✅ b) Microwave
Which ray penetrates human tissue most deeply?
a) Alpha
b) Beta
c) X-ray
d) Gamma
✅ d) Gamma
Which radiation has ionizing potential but is natural in background?
a) Gamma
b) UV-A
c) Infrared
d) Microwaves
✅ a) Gamma
Source of cosmic radiation:
a) Earth
b) Moon
c) Sun and stars
d) Water bodies
✅ c) Sun and stars
What blocks alpha radiation effectively?
a) Plastic
b) Air
c) Paper
d) Lead
✅ c) Paper
Most of the radiation in the universe is:
a) X-ray
b) Microwave
c) Gamma
d) IR
✅ b) Microwave
Explanation: Cosmic Microwave Background is dominant.
Light is considered radiation because:
a) It is made of particles
b) It needs a medium
c) It is an EM wave
d) It is mechanical
✅ c) It is an EM wave
The harmful effect of excessive radiation is:
a) Nerve stimulation
b) Genetic mutation
c) Cold
d) Low immunity
✅ b) Genetic mutation
A radioisotope used in radiation therapy is:
a) Cobalt-60
b) Oxygen-16
c) Iron-59
d) Helium-2
✅ a) Cobalt-60
Radiations are classified based on:
a) Energy
b) Shape
c) Temperature
d) Color
✅ a) Energy