**Current, Maximum, circuit**

Question by longdecember:

**What is the maximum current in the circuit?**

A 75 microFarad capacitor is connected in series with a 10 mH inductance and a switch. The capacitor is first charged to a voltage of 220 V. The charging battery is then removed. As soon as the switch is closed, the current begins to oscillate back and forth between one direction and the reversed direction. What is the maximum current in the circuit in units of A?

I am having trouble with this because I know the formula for current for an RL circuit, but this is an LC circuit, and I can't find it anywhere. Any help would be appreciated.

I also know that when current is maximum, the charge has to be zero because current and charge are 90 degrees out of phase, but I don't know where this would fit in.

Best answer:

*Answer by Bekki B*

When there's no battery in there, the voltage across the capacitor = - voltage across the inductor.

V cap = Q/C = -V ind = -L I' = -LQ''

The solution is a differential equation:

Q = Qmax cos (omega t)

where omega = sqrt (1/LC)

Qmax is the initial charge, which you got when the capacitor voltage Q/C = the battery voltage. So Qmax = VC.

So Q = Qmax cos (omega t)

Current is the time derivative of charge.

So I = Q' = - Qmax (omega) sin (omega t)

The maximum value, therefore, is Qmax * omega. Plug in all the numbers to solve for it.

Add your own answer in the comments!

Other posts like this, by keyword:

**Current**:

Current Events Brief 31 ...

Immobilisation of DNA on Chips I (Topics in Current Chemistry) (v. 1) ...

The Social Psychology of Education: Current Research and Theory ...

Addiction Recovery Management: Theory, Research and Practice (Current Clinical Psychiatry) ...

Medicine, 2001 Edition (Current Clinical Strategies Series) Reviews ...

The Contours of Psychiatric Justice: A Postmodern Critique of Mental Illness, Criminal Insanity, and the Law (Current Issues in Criminal Jus ...

Disability Research And Policy: Current Perspectives ...

Current Clinical Strategies Manual of HIV/AIDS Therapy 2003 Edition Reviews ...

High Voltage Direct Current Transmission (I E E Power Engineering Series) ...

Chronic Leukemias and Lymphomas: Clinical Management (Current Clinical Oncology) Reviews ...

**Maximum**:

Letters to Penthouse xxx: Extreme Sex, Maximum Pleasure (v. 30) ...

Trigun Maximum Volume 3: His Life As A. . . (Trigun Maximum (Graphic Novels)) Reviews ...

Trigun Maximum Volume 7: Happy Days (Trigun Maximum (Graphic Novels)) (Trigun Maximum, Vol. 7) (v. 7) Reviews ...

The Food Service Professional Guide to Waiter & Waitress Training: How to Develop Your Staff for Maximum Service & Profit (The Food ...

Past Climate Variability in South America and Surrounding Regions: From the Last Glacial Maximum to the Holocene (Developments in Paleoenvir ...

The Angel Experiment (Maximum Ride, Book 1) ...

SGIÂ® AltixÂ® UV Scales Microsoft Windows Server to Its Maximum ...

Trigun Maximum Volume 5: Break Out (Trigun Maximum (Graphic Novels)) ...

Fitness Without Exercise: The Proven Strategy for Achieving Maximum Health with Minimum Effort ...

Trigum Maximum Manga Set volumes 1- 8 (Trigun) Reviews ...

**circuit**:

RF Circuit Design: Theory & Applications (2nd Edition) ...

Surveillance, Closed Circuit Television and Social Control ...

What generates the current in the secondary circuit of the transformer? ...

## No comments:

## Post a Comment