LECT18_20721A

# LECT18_20721A - Quick Quiz 20.5 In this RL circuit driven...

This preview shows pages 1–6. Sign up to view the full content.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Quick Quiz 20.5 In this RL circuit, driven by an AC source of EMF, the inductor is an air-core solenoid. The switch is closed and after some time, the light bulb glows steadily. An iron rod is inserted into the solenoid, thereby increasing the strength of the B-field inside the solenoid. As the rod is being inserted, what happens to the brightness of the light bulb? Answer: L is increasing. So | Δ V L | = L( Δ I/ Δ t) is increasing. ε = Δ V R + Δ V L Δ V R is decreasing, the power dissipated in the lightbulb decreases, and its brightness decreases. Energy stored in an inductor EMF induced by the inductor prevents the battery from establishing the maximum current immediately. Battery must do extra work to produce current. Extra work: becomes potential energy stored in the B-field of the inductor PE = 1/2 L I 2 An RL circuit switch is closed at t=0, and the current begins to increase. R = 0.5 Ω . L = 3x10 –3 H. ε = 9V. How much potential energy is stored in the inductor at t=0, and t= ∞ ? At t=0: I=0. PE = 1/2 L I 2 = 0 At t= ∞ : I = ε /R: PE = 1/2 L I 2 = 1/2 L ( ε /R) 2 = 0.49J Application: traffic signals Several coils of wire create a solenoid Air-core L = ( μ ( N 2 / l ) )A “car-core”: L increases by μ / μ Device which measures inductance registers the change, triggers green signal. L Application: traffic signals Several coils of wire create a solenoid Air-core L = ( μ ( N 2 / l ) )A “car-core”: L increases by μ / μ Device which measures inductance registers the change, triggers green signal....
View Full Document

{[ snackBarMessage ]}

### Page1 / 30

LECT18_20721A - Quick Quiz 20.5 In this RL circuit driven...

This preview shows document pages 1 - 6. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online