degrees per second (deg/s) to terahertz (THz) conversion

What is degrees per second?

Degrees per second ($^{\circ}/s$) is a unit of angular speed, representing the rate of change of an angle over time. It signifies how many degrees an object rotates or turns in one second. Understanding this unit is crucial in various fields, from physics and engineering to animation and video games.

Definition and Formation

Degrees per second measures angular velocity, which describes how quickly an object rotates or revolves relative to a specific point or axis. Unlike linear speed (e.g., meters per second), angular speed focuses on rotational motion.

It is formed by dividing the angle in degrees by the time in seconds:

$$\text{Angular Speed} = \frac{\text{Angle (in degrees)}}{\text{Time (in seconds)}}$$

For example, if a spinning top rotates 360 degrees in one second, its angular speed is 360 $^{\circ}/s$.

Connection to Hertz and Revolutions Per Minute (RPM)

Degrees per second is related to other units of angular speed, such as Hertz (Hz) and Revolutions Per Minute (RPM).

• Hertz (Hz): Represents the number of cycles per second. One complete cycle is equal to 360 degrees. Therefore, 1 Hz = 360 $^{\circ}/s$.
• Revolutions Per Minute (RPM): Represents the number of complete rotations per minute. Since one revolution is 360 degrees and there are 60 seconds in a minute, you can convert RPM to degrees per second using the following formula:

$$\text{Degrees per second} = \frac{\text{RPM} \times 360}{60} = \text{RPM} \times 6$$

Relevant Laws and Figures

While there isn't a specific "law" directly associated with degrees per second, it's a fundamental unit in rotational kinematics and dynamics. These fields are governed by Newton's laws of motion adapted for rotational systems.

• Isaac Newton: His laws of motion form the basis for understanding how forces affect the angular motion of objects. For instance, the rotational equivalent of Newton's second law states that the net torque acting on an object is equal to the object's moment of inertia multiplied by its angular acceleration.

Real-World Examples

• Hard disk drives: A hard disk drive can spin at 7200 RPM, converting this to degrees per second: $7200 \times 6 = 43200$ $^{\circ}/s$
• Electric motors: The shaft of a small electric motor might spin at 3000 RPM, converting this to degrees per second: $3000 \times 6 = 18000$ $^{\circ}/s$
• DVD Player: DVD players rotate their disks at a rate that varies depending on which track is being read, but can easily exceed 1500 RPM.

Applications

• Robotics: Controlling the precise movement of robotic arms and joints relies on accurate angular speed measurements.
• Video Games: Degrees per second is used to control the rotation speed of objects and characters.
• Navigation Systems: Gyroscopes in navigation systems use angular speed to determine orientation and direction.
• Astronomy: Astronomers measure the angular speed of celestial objects, such as the rotation of planets or the movement of stars across the sky.

What is Terahertz (THz)?

Terahertz (THz) is a unit of frequency equal to one trillion (10^12) hertz. In other words:

$1 THz = 10^{12} Hz$

Frequency, measured in Hertz (Hz), represents the number of complete cycles of a wave that occur in one second. Therefore, a terahertz wave oscillates one trillion times per second. Terahertz radiation lies in the electromagnetic spectrum between the infrared and microwave bands, typically defined as the range from 0.1 to 10 THz.

How is Terahertz Formed?

Terahertz waves can be generated through various physical processes and technologies, including:

• Electronic methods: Using high-speed electronic circuits and devices like Gunn diodes and photomixers. These create oscillating currents at terahertz frequencies.
• Optical methods: Employing lasers and nonlinear optical crystals to generate terahertz waves through processes like difference frequency generation (DFG).
• Photoconductive antennas: Illuminating a semiconductor material with a short laser pulse, generating a burst of current that radiates terahertz waves.
• Synchrotron radiation: Accelerating charged particles to near the speed of light in a synchrotron produces broad-spectrum electromagnetic radiation, including terahertz.

Interesting Facts and Applications of Terahertz

• Non-ionizing Radiation: Unlike X-rays, terahertz radiation is non-ionizing, meaning it doesn't have enough energy to remove electrons from atoms and damage DNA, making it potentially safer for certain applications.

• Water Absorption: Terahertz waves are strongly absorbed by water. This property is both a challenge and an advantage. It limits their range in humid environments but also allows them to be used for moisture sensing.

• Security Screening: Terahertz imaging can penetrate clothing and other materials, making it useful for security screening at airports and other locations. It can detect concealed weapons and explosives.

• Medical Imaging: Terahertz imaging is being explored for medical applications, such as detecting skin cancer and monitoring wound healing. Its non-ionizing nature is a significant benefit.

• Materials Science: Terahertz spectroscopy is used to characterize the properties of various materials, including semiconductors, polymers, and pharmaceuticals.

Terahertz in Real-World Examples:

To understand the scale of terahertz, let's compare it to other frequencies:

• Radio Frequencies: FM radio broadcasts operate at around 100 MHz (0.0001 THz).
• Microwaves: Microwave ovens use frequencies around 2.45 GHz (0.00245 THz).
• Infrared: Infrared radiation used in remote controls has frequencies around 30 THz.
• Visible Light: Visible light spans frequencies from approximately 430 THz (red) to 790 THz (violet).
• Cell phones Cell phones operate between 0.7 to 3 GHz.

Therefore, terahertz waves fill the "terahertz gap" between commonly used radio/microwave frequencies and infrared light.

Well-Known People Associated with Terahertz

While no single person is universally credited as the "discoverer" of terahertz radiation, several scientists have made significant contributions to its understanding and development:

• Joseph von Fraunhofer (Early 1800s): Although not directly working with terahertz, his discovery of dark lines in the solar spectrum laid groundwork for spectroscopy, which is fundamental to terahertz applications.

• Jagadish Chandra Bose (Late 1800s): A pioneer in microwave and millimeter wave research, Bose's work with generating and detecting electromagnetic waves at these frequencies paved the way for terahertz technology.

• Martin Nuss (Late 1980s - Present): A leading researcher in terahertz science and technology, Nuss has made significant contributions to terahertz imaging and spectroscopy.

• Xi-Cheng Zhang (1990s - Present): Zhang is renowned for his work on terahertz time-domain spectroscopy (THz-TDS) and terahertz imaging.