Question 56: AC fundamentals

Question

An AC voltage source of variable angular frequency $$\omega$$ and fixed amplitude V0 is connected in series with a capacitance C and an electric bulb of resistance R (inductance zero). When $$\omega$$ is increased

Accepted Answer

Impedance of the circuit,
$$Z = \sqrt {{{({X_C})}^2} + {{(R)}^2}}  = \sqrt {{{\left( {{1 \over {\omega C}}} \right)}^2} + {R^2}} $$
As $$\omega$$ increases, Z decreases.
Current in the circuit, $$I = {{{V_0}} \over Z}$$
When $$\omega$$ is increased, the impedance of the circuit decreases and the current through the bulb increases. Therefore the bulb glows brighter.

Answer

the bulb glows dimmer.

Answer

the bulb glows brighter.

Answer

total impedance of the circuit is unchanged.

Answer

total impedance of the circuit increases.

AC fundamentals

An AC voltage source of variable angular frequency $\omega and fixed amplitude V0 is connected in series with a capacitance C and an electric bulb of resistance R (inductance zero). When \omega$ is increased

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