convection requires a medium is not the main difference, it is simply the most obvious aspect of what is a fundamentally different mechanism for transfering energy. Convection is the transfer of energy by movement of a medium, whereas radiation is the transfer of energy by, well, thermal radiation. Conduction also requires a medium, but, again, it is a fundamentally different mechanism than either convection or radiation; in this case it is the transfer of energy through a medium.
Unfortunately, analogies are hard but if you can visualize the particles involved, it would help. Picture the red hot iron you mentioned. On a molecular level, the material is emitting lots and lots of photons (hence why it is glowing red). The creation of these photons takes energy; energy from the heat of the iron. These photons leave the iron, pass through the environment, and eventually collide with some other object where they are absorbed and deposit their energy. This is radiative heat transfer. If that energy is deposited on your retina or a CCD (like in a digital camera), an image forms over time. This is how infrared goggles work and they would work equally well in high vacuum as here on earth.
In conduction, the next simplest example, there is no generation of photons (physics nerds forgive me for the sake of simplicity). The individual atoms in the object are vibrating with heat energy. As each atom gains energy from it's more energetic neighbors, so it gives up energy to its less energetic ones. Over time, the heat "travels" through the object.
In convection, the molecules of gas near the object gain energy, like in the conduction case, but those same molecules that gained energy then travel through the environment to some other location where they then give off their heat energy.
In summary:
radiation = generated and absorbed photonsconduction = molecules exciting their neighbors succesivelyconvection = molecules heated like in conduction, but then move to another location
I'd choose B as the answer.
Our entire social lives these days are mediated and we are now leaving in a mediated era. Social media, for instance, has profoundly influenced in inter-personal communication. Options A and D contributes to the interaction and the fulfillment of peoples’ social needs and social media has become a preferred mode of communication with the rise of digital and mobile technologies. Social media has negatively impacted and reduced face to face interactions of human beings, whether business wise or through personal communication. Option C also illustrates an effect of media on human communication, which only leaves us with option B
Answer:
"Security Kernel" is the correct answer for the above question.
Explanation:
- Security Kernel is a part of the kernel which is present in the operating system. The work of kernel is to manage the resource, boot the operating system and the other work.
- The security kernel is used to secure or control the access of the software and the hardware from the other source and the user which can access the computer for the wrong purpose.
- The above question asked about the central part of the operating system which is used to control access. This part is known as "Security Kernal".
