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  2. Universal motor - Wikipedia

    en.wikipedia.org/wiki/Universal_motor

    The universal motor is modified in several ways to allow for proper AC supply operation. There is a compensating winding typically added, along with laminated pole pieces, as opposed to the solid pole pieces found in DC motors. [2] A universal motor's armature typically has far more coils and plates than a DC motor, and hence fewer windings per ...

  3. Molecular model - Wikipedia

    en.wikipedia.org/wiki/Molecular_model

    A molecular model is a physical model of an atomistic system that represents molecules and their processes. They play an important role in understanding chemistry and generating and testing hypotheses .

  4. Molecular motor - Wikipedia

    en.wikipedia.org/wiki/Molecular_motor

    An alternative proposal is that, in contrast with all other biological motors, the force is not generated directly by the protein, but by the DNA itself. [9] In this model, ATP hydrolysis is used to drive protein conformational changes that alternatively dehydrate and rehydrate the DNA, cyclically driving it from B-DNA to A-DNA and back again ...

  5. Molecular machine - Wikipedia

    en.wikipedia.org/wiki/Molecular_machine

    Unlike a molecular motor, any mechanical work done due to the motion in a switch is generally undone once the molecule returns to its original state unless it is part of a larger motor-like system. The image on the right shows a hydrazone -based switch that switches in response to pH changes.

  6. Field coil - Wikipedia

    en.wikipedia.org/wiki/Field_coil

    Most three-phase AC field coils are used to generate a rotating field as part of an electric motor. Single-phase AC motors may follow either of these patterns: Small motors are usually universal motors, like the brushed DC motor with a commutator, but run from AC. Larger AC motors are generally induction motors, whether these are three-phase or ...

  7. History of atomic theory - Wikipedia

    en.wikipedia.org/wiki/History_of_atomic_theory

    The current theoretical model of the atom involves a dense nucleus surrounded by a probabilistic "cloud" of electrons. Atomic theory is the scientific theory that matter is composed of particles called atoms. The definition of the word "atom" has changed over the years in response to scientific discoveries.

  8. Biology - Wikipedia

    en.wikipedia.org/wiki/Biology

    In terms of its molecular structure, water is a small polar molecule with a bent shape formed by the polar covalent bonds of two hydrogen (H) atoms to one oxygen (O) atom (H 2 O). [33] Because the O–H bonds are polar, the oxygen atom has a slight negative charge and the two hydrogen atoms have a slight positive charge. [33]

  9. Directionality (molecular biology) - Wikipedia

    en.wikipedia.org/wiki/Directionality_(molecular...

    A furanose (sugar-ring) molecule with carbon atoms labeled using standard notation. The 5′ is upstream; the 3′ is downstream. DNA and RNA are synthesized in the 5′-to-3′ direction. Directionality, in molecular biology and biochemistry, is the end-to-end chemical orientation of a single strand of nucleic acid.