A solenoid with resistance 4Ω and inductance 6 mH is used in an automobile ignition circuit similar to that in Fig. 7.78. If the battery supplies 12 V, determine: the final current through the solenoid when the switch is closed, the energy stored in the coil, and the voltage across the air gap,

Question

A solenoid with resistance 4 Ω and inductance 6 mH is used in an automobile ignition circuit similar to that in Fig. 7.78. If the battery supplies 12 V, determine: the final current through the solenoid when the switch is closed, the energy stored in the coil, and the voltage across the air gap, assuming that the switch takes 1 μ s to open.

Accepted Answer

The final current through the coil is

[latex] I = \frac{V_{s}}{R}= \frac{12}{4} = 3 A [/latex]

The energy stored in the coil is

[latex] W = \frac{1}{2} = L I² = \frac{1}{2} × 6 × 10^{-3} × 3 ² = 27 mJ [/latex]

The voltage across the gap is

[latex] V = L \frac{ΔI}{Δt} = 6 × 10^{-3} × \frac{3}{1 × 10^{-6}} = 18 kV [/latex]

Question 7.22: A solenoid with resistance 4Ω and inductance 6 mH is used in......

Related Answered Questions

For the op amp circuit in Fig. 7.55(a), find vo for t > 0 given that v(0)= 3 V . Let Rf = 80 kΩ, R1 = 20 kΩ, and C = 5 μF. ...

Verified Answer:

At t = 0 , switch 1 in Fig. 7.53 is closed, and switch 2 is closed 4 s later. Find i(t) for t > 0.Calculate i for t = 2s and t = 5s. ...

Verified Answer:

Determine v(t) and vo(t) in the circuit of Fig. 7.57 ...

Verified Answer:

Find the step response vo(t) for t > 0 in the op amp circuit of Fig. 7.59. Let vi= 2u(t) V, R1 = 20kΩ,Rf= 50kΩ,R2=R3= 10kΩ, C= 2µF. ...

Verified Answer:

Use PSpice to find the response i(t) for t > 0 in the circuit of Fig. 7.63 ...

Verified Answer:

In the circuit of Fig. 7.67(a), determine the response v(t). ...

Verified Answer:

Consider the circuit in Fig. 7.73, and assume that R1=1.5 MΩ,0 < R2< 2.5 MΩ(a) Calculate the extreme limits of the time constant of the circuit. (b) How long does it take for the lamp to glow for the first time after the switch is closed? LetR2 assume its largest value. ...

Verified Answer:

The coil of a certain relay is operated by a 12-V battery. If the coil has a resistance of 150 Ω and an inductance of 30 mH and the current needed to pull in is 50 mA, calculate the relay delay time. ...

Verified Answer:

Verified Answer:

Find i(t) in the circuit of Fig. 7.51 for t > 0 . Assume that the switch has been closed for a long time. ...

Verified Answer: