Question:
Electromagnetic radiation used to kill germs in water purifiers is:
Electromagnetic radiation used to kill germs in water purifiers is:
Show Hint
UV rays damage the DNA of germs, so they are used in water purifiers. Microwaves, gamma rays and radio waves are used elsewhere.
Updated On: Nov 12, 2026
Microwaves
Ultraviolet rays
Gamma rays
Radio waves
Show Solution
Verified By Collegedunia
The Correct Option is B
Solution and Explanation
Step 1: Understanding the Concept:
Electromagnetic waves of different frequencies have different uses. Water purifiers need a wave that damages germs but is safe to use inside a household device.
Step 2: Why ultraviolet rays:
Ultraviolet (UV) rays have wavelengths of about 10 nm to 400 nm and photon energies higher than visible light.
UV-C light, of about 254 nm, is absorbed by the DNA of bacteria and viruses. It damages the DNA, so the germs cannot multiply and die.
Step 3: Why the other options are wrong:
(A) Microwaves heat water molecules. They are used in ovens and radar, not to kill germs in a purifier.
(C) Gamma rays are very penetrating and harmful. They are used in nuclear medicine and sterilising medical goods, not in home purifiers.
(D) Radio waves have the lowest energy. They are used for communication and have no germicidal effect.
Final Answer:
Ultraviolet rays kill germs in water purifiers. This is option (B). \[ \boxed{\text{(B) Ultraviolet rays}} \]
Electromagnetic waves of different frequencies have different uses. Water purifiers need a wave that damages germs but is safe to use inside a household device.
Step 2: Why ultraviolet rays:
Ultraviolet (UV) rays have wavelengths of about 10 nm to 400 nm and photon energies higher than visible light.
UV-C light, of about 254 nm, is absorbed by the DNA of bacteria and viruses. It damages the DNA, so the germs cannot multiply and die.
Step 3: Why the other options are wrong:
(A) Microwaves heat water molecules. They are used in ovens and radar, not to kill germs in a purifier.
(C) Gamma rays are very penetrating and harmful. They are used in nuclear medicine and sterilising medical goods, not in home purifiers.
(D) Radio waves have the lowest energy. They are used for communication and have no germicidal effect.
Final Answer:
Ultraviolet rays kill germs in water purifiers. This is option (B). \[ \boxed{\text{(B) Ultraviolet rays}} \]
Was this answer helpful?
0
0
Top CBSE CLASS XII Physics Questions
- A boy of mass 50 kg is standing at one end of a, boat of length 9 m and mass 400 kg. He runs to the other, end. The distance through which the centre of mass of the boat boy system moves is
- A capillary tube of radius r is dipped inside a large vessel of water. The mass of water raised above water level is M. If the radius of capillary is doubled, the mass of water inside capillary will be
- A circular disc is rotating about its own axis. An external opposing torque 0.02 Nm is applied on the disc by which it comes rest in 5 seconds. The initial angular momentum of disc is
- A circular disc is rotating about its own axis at uniform angular velocity \(\omega.\) The disc is subjected to uniform angular retardation by which its angular velocity is decreased to \(\frac {\omega}{2}\) during 120 rotations. The number of rotations further made by it before coming to rest is
- A constant power is supplied to a rotating disc. The relationship between the angular velocity $\omega$ of the disc and number of rotations (n) made by the disc is governed by
View More Questions
Top CBSE CLASS XII Questions
- 2, b, c are in A.P. and the range of determinant $\begin{vmatrix}1&1&1\\ 2&b&c\\ 4&b^{2}&c^{2}\end{vmatrix}$ is [2, 16]. Then find range of c is
- A boy of mass 50 kg is standing at one end of a, boat of length 9 m and mass 400 kg. He runs to the other, end. The distance through which the centre of mass of the boat boy system moves is
- A capillary tube of radius r is dipped inside a large vessel of water. The mass of water raised above water level is M. If the radius of capillary is doubled, the mass of water inside capillary will be
- A circular disc is rotating about its own axis. An external opposing torque 0.02 Nm is applied on the disc by which it comes rest in 5 seconds. The initial angular momentum of disc is
- A circular disc is rotating about its own axis at uniform angular velocity \(\omega.\) The disc is subjected to uniform angular retardation by which its angular velocity is decreased to \(\frac {\omega}{2}\) during 120 rotations. The number of rotations further made by it before coming to rest is
View More Questions