signal
Definition
A signal is a physical quantity that conveys information about its source. Signals can be used to communicate between people, animals, and machines. They can also be used to control devices and to transmit data.
Signals can be classified into two main types: analogue and digital.
Analogue signals are continuous signals that can take on any value between a minimum and maximum value. For example, the voltage of an electrical signal can be an analogue signal.
Digital signals are discrete signals that can only take on a finite number of values. For example, the binary digits 0 and 1 are digital signals.
Analogue signals are often used to represent real-world quantities, such as temperature, pressure, and sound. Digital signals are often used to represent information that can be easily processed by computers, such as text and numbers.
Signals can be transmitted through a variety of media, including air, wires, and optical fibres. The type of media used to transmit a signal affects its speed and range.
Signals can be amplified to increase their strength. They can also be filtered to remove unwanted noise.
Signals can be used to control devices and to transmit data. For example, a signal from a remote control can be used to turn on a TV. A signal from a computer can be used to transmit data over the internet.
How can the word be used?
The soldier signalled to his comrades to attack.
Different forms of the word
Noun:
- a gesture, sound, or other means of conveying information or instructions.
- a distinctive mark or sign.
- a sudden change in the behaviour of an animal or plant, indicating the presence of something.
Verb:
- to give a signal to someone.
- to make a gesture or sound to convey information or instructions.
- to indicate the presence of something by a sudden change in behaviour.
Etymology
The word "signal" comes from the Latin word "signum", which means "mark" or "sign".
The first recorded use of the word "signal" in English was in the 14th century.
The word "signal" is a Latin word, and it is related to the English word "signature".
Question
What is a signal?
AQA Science Exam Question and Answer
Question:
Explain how nerve cells transmit signals within the nervous system and discuss the importance of these signals in coordinating various physiological processes in the human body.
Answer:
Nerve cells, or neurons, transmit signals within the nervous system through a process known as neurotransmission. When a neuron receives a stimulus, it generates an electrical impulse called an action potential. This electrical signal travels along the neuron's axon and reaches the synapse, a small gap between neurons.
At the synapse, the action potential triggers the release of neurotransmitters, which are chemical messengers stored in vesicles. These neurotransmitters diffuse across the synapse and bind to receptors on the neighbouring neuron's membrane, transmitting the signal from one neuron to another.
This communication between neurons is vital for coordinating various physiological processes in the human body. For instance, in the central nervous system, neurons transmit signals that regulate muscle contractions, sensory perception, memory, and emotions. In the peripheral nervous system, neurons facilitate the transmission of sensory information to the brain and initiate motor responses.
The precise and rapid transmission of signals ensures the proper functioning of the body's systems, enabling us to respond to our environment, move, think, and experience sensations. Any disruptions in this signalling process can lead to neurological disorders and affect overall bodily functions.