(a)(i) A dielectric is an insulating material (solid, liquid or gas) separating the two plates of a capacitor.
(ii) Using C = \(\frac{\xi_1.\xi_oA}{d} = \frac{900 \times 8.85 \times 10^{-12} \times 9.6 \times 10^{-3}}{2.25 \times 10^{-4}}\)
= 3.4 x 10\(^{-7}\)

(b)(i) A voltmeter has a higher resistance. Reason: A voltmeter is connected inparallel in a circuit to allow passage of minimal current through it; hence the circuit current is not significantly affected.
(ii)

\(\frac{1}{R_1} = \frac{1}{400} + \frac{1}{400}\) \(R_1 = 200\Omega\)
\(\frac{1}{R_2} = \frac{1}{800} + \frac{1}{800}\) \(R_1 = 400\Omega\)
RT= 200 + 400 = 600\(\Omega\)
I = \(\frac{V_T}{R_T} = \frac{6}{600}\) = 0.01A
Voltmeter reading
= Pd across R\(_2\)
= 0.01A
Voltmeter reading = Pd across R\(_2\)
= 0.01 x 400 = 4v

(c)

\(\frac{1}{R_p} = \frac{1}{2} + \frac{1}{2} = \frac{1 + 1}{2} = \frac{2}{2}\)
Note: This catadation is for the two resistors in parallel.
R\(_T = 2 + 1 + 2 = 5\Omega\)