An alternating emf source with amplitude 14.9 14.9 V and an adjustable driving frequency f d fd is connected in series with a 59.4 59.4 Ω resistor and a 23.7 23.7 μF capacitor. At what value of f d fd are the amplitudes of the voltages across the resistor and capacitor equal?

Respuesta :

Answer:

113.0 Hz

Explanation:

In a RC circuit with alternating current, the voltage across the resistor is given by Ohm's Law:

[tex]V_R = IR[/tex]

where

I is the current in the circuit

R is the resistance of the resistor

While the voltage across the capacitor is given by:

[tex]V_C = IX_C[/tex]

where

[tex]X_C=\frac{1}{2\pi f C}[/tex] is the impedance of the capacitor, where

f is the frequency

C is the capacitance

The voltages across the resistor and the capacitor are equal when

[tex]V_R = V_C[/tex]

So

[tex]IR=\frac{I}{2\pi fC}[/tex]

Which can be rewritten as

[tex]f=\frac{1}{2\pi RC}[/tex]

In this problem:

[tex]R=59.4\Omega[/tex] is the resistance

[tex]C=23.7\mu F = 23.7\cdot 10^{-6}F[/tex] is the capacitance

Substituting, we find the frequency at which this happens:

[tex]f=\frac{1}{2\pi (59.4)(23.7\cdot 10^{-6})}=113.0 Hz[/tex]

The value of fd represents the amplitudes of the voltages across the resistor and capacitor equal to 113.0 Hz.

Ohm law:

Here

V = IR

Here.

I is the current in the circuit

R is the resistance of the resistor

Now the voltage across the capacitor and resistor should be  provided by

Vr = Vc

IR = 1/2πFc

Here

f = 1 /2πRC

So,

= 1/2π(59.4)(23.7.10^-60

= 113.0 Hz

Hence, The value of fd represents the amplitudes of the voltages across the resistor and capacitor equal to 113.0 Hz.

Learn more about ohm law here:  https://brainly.com/question/17139885?referrer=searchResults