There are 4 fundamental forces, that exists in nature:
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Gravitational forces
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Electric forces
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Magnetic forces
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Nuclear forces
Electricity:
A Physical phenomenon associated with presence of electric charge (stationary or moving).
Static Electricity:
Accumulated electric charge on non-conducting material, results from imbalance of positive and negative charges between object.
free electron = flowing charge
Conductor = permits very mobile electrons to flow freely and easily releases electrons, such as metal.
Semiconductor = intermediate conductivity, increases with temperature, such as silicon.
Insulator = extremely high resistance to flow of charge, such as rubber, wood, plastic.
What is electric potential energy ?
Electric potential energy of a charge descrbes the amount of its stored energy.
Electrostatic force converts electric potential energy to kinetic energy.
Charge flow = kinetic energy.
Electrical resistance: material’s tendency to resist the flow of charge (current).
Electrical conductance: material’s ability to conduct the flow of charge (current).
Electrical resistance is measured as the ratio of voltage and current.
What is Ohm's Law:
V = I. R
V = voltage (Volt)
I = current (Amp)
R = resistance (Ohm)
Factors affecting resistance:
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length of the wire
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material of the wire
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cross-sectional area of the wire.
electric circuit = a closed path/line/loop of conducting material that allows flow of current.
electric field = a region associated with the existence of a force generated by a distribution of electric charge.
Electric field is a vector quantity (force) exerted by a charged particle on the surrounding charged particles.
Electric field is measured as electric force per unit charge
magnet: an object/device that produces magnetic field and exerts attractive/repulsive forces.
magnetic field: a region / space near a magnet or moving charges exerting magnetic force.
electric currents + magnetic moments give rise to magnetic field. Magnetic field produces Magnetism, (attractive / repulsive force).
magnetic field in sub-atomic level
magnetic moment: property of a magnet that interacts with an applied magnetic field to generate a mechanical moment. It’s a measure of the tendency to align with a magnetic field.
properties of magnetic field lines
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Lines are closed loops
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Direction from the north pole
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Lines penetrate magnetic materials
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Strength is proportional to the density
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Lines bend at the surface of magnetic materials
induced magnets
induced by electric current
consequences of nucleus in external magnetic field:
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Larmor Precession
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spin flip
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Zeeman Effect
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absorption of EM radiation
