University Physics Volume 2

# Key Equations

### Key Equations

 Permeability of free space $μ0=4π×10−7T⋅m/Aμ0=4π×10−7T⋅m/A$ Contribution to magnetic fieldfrom a current element $dB=μ04πIdlsinθr2dB=μ04πIdlsinθr2$ Biot–Savart law $B→=μ04π∫wireIdl→×r^r2B→=μ04π∫wireIdl→×r^r2$ Magnetic field due to along straight wire $B=μ0I2πRB=μ0I2πR$ Force between two parallel currents $Fl=μ0I1I22πrFl=μ0I1I22πr$ Magnetic field of a current loop $B=μ0I2R(at center of loop)B=μ0I2R(at center of loop)$ Ampère’s law $∮B→·dl→=μ0I∮B→·dl→=μ0I$ Magnetic field strengthinside a solenoid $B=μ0nIB=μ0nI$ Magnetic field strength inside a toroid $B=μoNI2πrB=μoNI2πr$ Magnetic permeability $μ=(1+χ)μ0μ=(1+χ)μ0$ Magnetic field of a solenoidfilled with paramagnetic material $B=μnIB=μnI$