(i) What is dielectric?
(ii) A parallel plate capacitor consists of two plates each of area 9.6 x 10(^{-2})m(^2), separated by a dielectric of thickness 2.25 x 10(^{-3}) and dielectric constant 900. Calculate the capacitance of the capacitor. [ (varepsilon_o) = permittivity of free space = 8.85 x 10(^{-12})Fm(^{-1})]
(b) (i) Which of the following devices has a higher resistance; an ammeter or a voltmeter? Give a reason for your answer.
(ii)
The resistance of the voltmeter in the circuit diagram illustrated above is 800(Omega), Calculate the voltmeter reading.
(c)
A battery of negligible internal resistance is connected to a set of resistors as illustrated in the circuit diagram above. Determine the equivalent resistance of the circuit.
Explanation
(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 = 200Omega)
(frac{1}{R_2} = frac{1}{800} + frac{1}{800}) (R_1 = 400Omega)
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 = 5Omega)