Physics IB glossary - electricity and magnetism
|Coulomb's law|| F=k (Q₁Q₂/r²)|
electric force between two point charges.
also for two spherical objects, where r is measured from centre to centre. attractive for unlike charges and repulsive for like charges.
|Current||charge per unit time passing through cross-sectional area.|
|Electric field|| electric force per unit charge experienced by positive test charge. Vector. |
point charge Q produces electrical field magnitude
|electric potential|| V=k(Q/r)|
work per unit charge in bringing test charge from infinity to a given point within electric field. electric potential is constant within conductor. scalar.
|Electric Power|| P=VI=RI²=V²/R|
rate of dissipation of electrical energy
|Electron volt|| 1eV=1.6x10⁻¹⁹J|
work done moving charge of e=1.6x10⁻¹⁹ through PD of 1volt.
|Emf||work done in moving a positive test particle across the terminals of a battery. εI = total power dissipated when I is current in circuit.|
|Faraday's law|| ε=N (ΔΦ/Δt)|
induced emf in loop is rate of change with time of magnetic flux linkage through the loop.
|Lenz's law||direction of induced current is such to oppose change that created it.|
|Magnetic field strength|| vector. magnitude is given by force on a unit charge moving at right angles to field with unit velocity. MFS, B, is at right angles for force it exerts. measured in Tesla.|
in straight wire: B=μ₀ (I/2πr)
in solenoid : B=μ₀ (NI/L)
|Magnetic flux linkage|| Φ=NBAcosθ scalar.|
product of magnetic field strength, area of loop, no. turns of wire, and cosine of angle between the area normal and B
|Magnetic force|| F=qvBsinθ = BILsinθ|
moving charged particle or current will experience force in a magnetic field.
|Ohm's law||current in a conductor at constant T is proportional to voltage across it.|
|path in electric field||for charged particle: parabola, or straight line if particle moves along a straight field line.|
|path in magnetic field|| for charged particle: circle if moving at right angle to field, a helix, or a straight line if particle moves along a straight field line.|
radius of circular path: R=mv/qB
|Rms current|| √ of average of square of current. |
for sinusoidally varying currents = peak voltage/ √2
|Rms voltage|| √ of average of square of voltage. |
for siusoidally varying voltage = peak voltage / √2