The circular plates of a parallel-plate capacitor have a radius of 30 mm. A steady 0.43-mA current is charging the initially uncharged capacitor, and the surface charge on the plates is distributed uniformly. The flat circular surface between the capacitor plates is coaxial and parallel to the plates, and has a radius of 13 mm. Calculate the magnetic field at any point on the circumference of the circular region (in Tesla).

Solution :

The electric field between two plates is given by

where

permitivity of free space

 q = charge

 A = surface area

It is given that  :

the radius of the circular plates , r = 30 mm

the current, I = 0.43 mA

Therefore, Magnetic field can be found by

  the grams     of oxygen gas   that can be produced     is 20.6   grams of o₂

calculation

2liclo₃ →   2 licl + 3 o₂

step 1:   find the moles of liclo₃

moles = mass÷ molar mass

from periodic table the molar mass of liclo₃ =6.9 +35.5   +(16 x3) =90.4 g/mol

moles=38.7 g÷90.4 g/mol=0.4281   moles

step 2:   use the   mole ratio   to calculate the moles of o2

from equation above, liclo₃: o₂   is 2: 3  

therefore the moles of   o₂=0.4281 moles x3/2 =0.6422   moles

step 3: find mass   of o₂

mass= moles x molar mass

from periodic table the   molar mass of   o₂ = 16 x2= 32 g/mol

mass=0.6422   moles   x   32 g/mol = 20.6 grams of o₂

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