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
Answer:
FFF4
Explanation:
Binary representation of 12 = 00001100
Expressing it in hexadecimal format : 0C
Binary representation of -12:
Step 1 : Computing 1's complement for 12 =11110011
Step 2 : Adding 1 to 1's complement to get the 2's complement =>
11110011+1 = 11110100
Converting the 2's complement representation to hexadecimal format:
F4 ( 8 bit representation) or FFF4 ( 16 bit representation)
Answer:
The solution code is written in Java.
- public static void swapArrayEnds(int myArray[]){
- int lastIndex = myArray.length-1;
- int temp = myArray[0];
- myArray[0] = myArray[lastIndex];
- myArray[lastIndex ] = temp;
- }
Explanation:
First create the swapArrayEngs method that take one input array parameter (Line 1).
Since we need to swap the first and last element of the array, we need to get the first index and last index of the array. The first index is 0 and the last index can be calculated by subtracting the length of array from 1 (Line 2).
Next, we can create a temp variable to hold the value of the first element (Line 3). Then we use the lastIndex the get the value of last element and assign it to the first element of array (Line 4). Lastly, we assign the temp (holding the initial first element value) to the last element of array (Line 5).