A parallel plate capacitor of area \( A = 16 \, \text{cm}^2 \) and separation between the plates \( 10 \, \text{cm} \), is charged by a DC current. Consider a hypothetical plane surface of area \( A_0 = 3.2 \, \text{cm}^2 \) inside the capacitor and parallel to the plates. At an instant, the current through the circuit is 6A. At the same instant the displacement current through \( A_0 \) is _____ mA.
To calculate the displacement current, we first revisit the displacement current formula within a capacitor. The displacement current (\(I_d\)) is given by:
\(I_d = \varepsilon_0 \frac{d\phi_E}{dt}\)
where \(\varepsilon_0\) is the permittivity of free space and \(\frac{d\phi_E}{dt}\) is the rate of change of electric flux.
The electric flux (\(\phi_E\)) is defined as:
\(\phi_E = E \cdot A = \frac{Q}{\varepsilon_0} \cdot A\)
where \(Q\) is the charge and \(E\) is the electric field. For a capacitor, \(I = \frac{dQ}{dt}\), thus \(\frac{d\phi_E}{dt} = \frac{1}{\varepsilon_0} \cdot \frac{dQ}{dt} \cdot A\).
Substituting in the equation for \(I_d\):
\(I_d = A \cdot \frac{1}{\varepsilon_0} \cdot I\)
Given \(A_0 = 3.2 \, \text{cm}^2 = 3.2 \times 10^{-4} \, \text{m}^2\) and \(I = 6 \, \text{A}\), with \(\varepsilon_0 = 8.854 \times 10^{-12} \, \text{F/m}\), plug in the values:
\(I_d = 3.2 \times 10^{-4} \cdot \frac{6}{8.854 \times 10^{-12}}\)
Simplifying:
\(I_d \approx 2.17 \times 10^{-3} \, \text{A} = 2170 \, \text{mA}\)
The displacement current through \(A_0\) is therefore correctly calculated as 2170 mA, which is within the range provided (1200 mA).
A black body is at a temperature of 2880 K. The energy of radiation emitted by this body with wavelength between 499 nm and 500 nm is U1, between 999 nm and 1000 nm is U2 and between 1499 nm and 1500 nm is U3. The Wien's constant, b = 2.88×106 nm-K. Then,


What will be the equilibrium constant of the given reaction carried out in a \(5 \,L\) vessel and having equilibrium amounts of \(A_2\) and \(A\) as \(0.5\) mole and \(2 \times 10^{-6}\) mole respectively?
The reaction : \(A_2 \rightleftharpoons 2A\)