Which is an example of negative feedback?

I came across this term for the first time.

Can anyone explain what it is and why we use it.

Thanks. It's a term used to describe the process by which something (like a temperature or some other parameter) changes in response to the change in some other parameter (like the amount of heat added or removed). For example, if we add heat to a substance at constant pressure, we observe that its temperature increases, ie, temperature is a function of the amount of heat added. This is known as positive feedback.

On the other hand, if we observe that the temperature does not increase, but instead decreases, ie, temperature is a function of the amount of heat removed, then we say that temperature is negative feedback. The same can be said for any other quantity that changes with respect to the amount of some other quantity.

In short, a system (like an electronic circuit) can have positive or negative feedback. This kind of feedback can be positive or negative, depending on whether the change in a parameter causes an increase or decrease in some other parameter.

Negative feedback occurs when you start with an initial condition and you change one part of the system while keeping all the other parts unchanged and the system ends up in a different state than it would have been without the change. A common example would be if you apply a voltage to a resistor and the resistance rises because it is conducting heat. This is a positive feedback situation.

A simple example where a negative feedback situation would occur is if you have an amplifier with a gain of 100 and you connect a variable resistor between the amplifier inputs and the ground. If you increase the resistance by increasing the voltage of the variable resistor, the output voltage would fall. This is because a higher resistance means less current will flow through the amplifier, but the amplifier's gain of 100 means it will still amplify the input signal by a factor of 100.

An example of positive feedback is an electric motor. If you connect a resistor in parallel to the coil of the motor, the current flow through the resistor increases proportionally to the winding current.

The winding current is a function of the torque applied to the rotor of the motor. The torque is a function of the speed of the motor. The speed is a function of the current flowing in the winding.

What are positive and negative feedback loops in the environment?

If you answered something about CO2?

Then the first problem is solved.

However, if you said Something about plants and bacteria then my answer is The hell with that! For all of our sakes, I want to take a serious moment to define positive and negative feedback loops. Feedback Loops describe system dynamics, a concept that is used throughout the sciences (chemistry, physics, biology, etc.). Basically, feedback loops describe how the entire system works together in response to changes in the inputs. Thus, positive feedback loops cause a system to become unstable and chaotic, and negative feedback loops stabilize a system from becoming unstable and chaotic.

In essence, feedback loops are a way of describing things like this: If you add more woodchips to the compost, you can turn it into a garden again. And: If you feed the chickens, they will lay more eggs. If you give a plant sugar it will grow larger. When applied to climate dynamics, the basic idea behind feedback loops is this: a warmer atmosphere causes more cloud cover, which causes more heat to be reflected back into space. More heat is reflected back into space, causing more cloud cover, which causes more heat. And so on. The same is true for every single change in Earth's climate; for example, a warmer ocean can create more clouds, which will block the sun from coming through. Or, if the ocean warms because of greenhouse gases, there will be less sunlight, which will cause the ocean to heat up more, which will cause more cloud cover, which will cause more heat.

Feedback loops have been studied by climatologists for decades. I have often referred to them in previous posts on how changes in atmospheric CO2 might be related to changes in plant photosynthesis. For example, a previous post on photosynthesis talked about how warming temperatures might increase plant-based carbon storage by improving photosynthetic efficiency. Warming temperatures might also help drive soil fertility down into deeper soils due to soil microfauna activity; see also this paper.