(a) Sketch the magnetic flux pattern around a long; straight, current-carrying wire
(b) State two methods by which the sensitivity of a moving-coil galvanometer can be increased.
(c) A series RLC circuit comprises a 100-(Omega) resistor, a 3-H inductor and a 4-(mu)f capacitor. The a.c source of tile circuit has an e.m.f of 100V and a frequency of 160 Hz.
(i) Draw the circuit diagram of the arrangement. Calculate the:
(ii) capacitive reactance;
(iii) inductive reactance:
(iv) impedance of the circuit;
(v) current in the circuit;
(vi) average power dissipated in the circuit.
Explanation
(a)
(b) The sensitivity is increased by a weak spring and increasing the strength of the magnet C
(c)(i)
(ii) X = (frac{1}{2 pi FC} = frac{1}{2 pi frac{160}{pi} times 4}) = 781(Omega)
(iii) X(_L) = 2(pi)fL = 2(pi) x (frac{160}{pi}) x 3 = 960(Omega)
(iv) Z = (sqrt{R^2 + (X_L – X_c)^2} = sqrt{100^2 + (960 – 781)^2}) = 205(Omega)
(v) I = (frac{v}{z} = frac{100}{205} = 0.49A)
(vi) P = I(^2R) = (0.49)(^{2}) x 100
= 23.795 W = 24W