Forces repelled

AC Dielectrophoresis Lab-on-Chip Devices, Fig. 3 Dielectrophoresis of particles with interdigitated electrodes (side view). Particles experiencing pDEP are attracted to the edges of the electrode, while nDEP forces repel the particle to the middle of the electrode... 

One of the remarkable properties of an atomic mirror is its ability to reflect atoms in a certain quantum state. That the atomic mirror is quantum-state-selective follows from the character of the relationship between the gradient force and the detuning. When the detuning is positive, the gradient force repels an atom from the surface, and thus specular reflection takes place. With negative detuning, the force attracts an atom to the surface, and so diffusive reflection is observed. 

Note that negative Acoj (red detuning) produces a force attracting the atom to the intensity maximum while positive (blue detuning) repels the atom away from the intensity maximum. The spontaneous force or cooling force can also be written in tenns of the saturation parameter and the spontaneous emission rate. 

Fig. 1. Motion of a material point on the body over time (left, short time interval right, long interval). The rigid body swings repeatedly toward the plane where it is repelled by the strong short-range force.

Electrostatics is the study of interactions between charged objects. Electrostatics alone will not described molecular systems, but it is very important to the understanding of interactions of electrons, which is described by a wave function or electron density. The central pillar of electrostatics is Coulombs law, which is the mathematical description of how like charges repel and unlike charges attract. The Coulombs law equations for energy and the force of interaction between two particles with charges q and q2 at a distance rn are... 

All of the material in this text and most of chemistry generally can be understood on the basis of what physicists call the electromagnetic force Its major principle is that opposite charges attract and like charges repel As you learn organic chemistry a good way to start to connect structure to properties such as chemical reactivity is to find the positive part of one molecule and the neg ative part of another Most of the time these will be the reactive sites... 

All of the forces in chemistry except for nuclear chemistry are electrical Opposite charges attract like charges repel This simple fact can take you a long way... 

The molecular dipstick microscope is related to the AFM. It measures lubricant film thickness. The probe is lowered into the oil film on a surface (like the automobile engine crankcase dipstick). The tip is attracted to the surface by the surface tension of the film but repelled by van der Waal s forces from the hard substrate. By noting the height of the probe from the two surfaces as it makes contact, the film thickness can be measured with a precision of about 0.5 nm. 

This model had an immediate nuclear problem because the positive charges in the nucleus repel each other. The nucleus should thus blow itself apart. This model clearly required a new force to hold the particles in the nucleus together. 

Principle of Operation. Electrical current flows are induced in all conductors when exposed to an a-c field. These currents generate a magnetic field surrounding the conductors which oppose the field being produced by the a-c field with a force sufficient to repel the conductor. Eigure 16 illustrates this principle by showing a rotor consisting of many poles. 

Ejfect of Gas Saturation in Scrubbing If hot unsaturated gas is introduced into a wet scrubber, spray particles will evaporate to cool and saturate the gas. The evaporating liquid molecules moving away from the target droplets will repel particles which might collide with them. This results in the forces of diffusiophoresis opposing particle... 

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