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An ac generator operates at a rotational frequency of 60 Hz and produces a maximum emf of 100 V. Assume that its output at is zero. What is the instantaneous emf (a) at ? (b) at ? (c) at t? (d) How much time elapses between successive 0-volt outputs? (e) What maximum emf would this generator produce if it were operated, instead, at 120 Hz?

Respuesta :

Answer:

(a). The instantaneous emf at [tex]t = \dfrac{1}{240}[/tex] is 100 V.

(b). The instantaneous emf at [tex]t = \dfrac{1}{120}[/tex] is 0 V.

(c). The instantaneous emf at [tex]t = \dfrac{t}{376.9}[/tex] is [tex]100\times\sin(57.29\ t)[/tex].

(d).  The time elapses is 0.00416 sec.

(e). The maximum voltage is 100 V.

Explanation:

Given that,

Frequency = 60 Hz

Emf = 100 V

We need to calculate the angular frequency

Using formula of angular frequency

[tex]\omega=2\pi f[/tex]

Put the value into the formula

[tex]\omega=2\pi\times60[/tex]

[tex]\omega=376.9\ rad/s[/tex]

(a). At [tex]t = \dfrac{1}{240}[/tex]

We need to calculate the instantaneous emf

Using formula of instantaneous emf

[tex]V_{inst}=V\sin\omega t[/tex]

Put the value into the formula

[tex]V_{inst}=100\sin\times376.9\dfrac{1}{240}[/tex]

[tex]V_{inst}=100\sin(360\times\dfrac{1.57}{2\pi})[/tex]

[tex]V_{inst}=100\times\sin90[/tex]

[tex]V_{inst}=100\ V[/tex]

(b). At [tex]t =\dfrac{1}{120}[/tex]

We need to calculate the instantaneous emf

Using formula of instantaneous emf

[tex]V_{inst}=V\sin\omega t[/tex]

Put the value into the formula

[tex]V_{inst}=100\sin\times376.9\dfrac{1}{120}[/tex]

[tex]V_{inst}=100\sin(360\times\dfrac{3.14}{2\pi})[/tex]

[tex]V_{inst}=100\times\sin180[/tex]

[tex]V_{inst}=0\ V[/tex]

(c). At [tex]t = \dfrac{t}{376.9}[/tex]

We need to calculate the instantaneous emf

Using formula of instantaneous emf

[tex]V_{inst}=V\sin\omega t[/tex]

Put the value into the formula

[tex]V_{inst}=100\sin\times376.9\times \dfrac{t}{376.9}[/tex]

[tex]V_{inst}=100\sin(360\times\dfrac{ t}{2\pi})[/tex]

[tex]V_{inst}=100\times\sin(57.29\ t)[/tex]

(d). The maximum instantaneous voltage occurred at [tex]t =\dfrac{1}{240}[/tex] is 100 V and the maximum instantaneous voltage occurred at [tex]t =\dfrac{1}{120}[/tex] is 0 V .

We need to calculate the time elapses

Using formula of time

[tex]t=\dfrac{1}{120}-\dfrac{1}{240}[/tex]

Put the value into the formula

[tex]t=\dfrac{1}{240}[/tex]

[tex]t=0.00416\ sec[/tex]

(e). The maximum voltage does not depend upon the frequency.

So, The maximum voltage is 100 V.

Hence, (a). The instantaneous emf at [tex]t = \dfrac{1}{240}[/tex] is 100 V.

(b). The instantaneous emf at [tex]t = \dfrac{1}{120}[/tex] is 0 V.

(c). The instantaneous emf at [tex]t = \dfrac{t}{376.9}[/tex] is [tex]100\times\sin(57.29\ t)[/tex].

(d).  The time elapses is 0.00416 sec.

(e). The maximum voltage is 100 V.