{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

# hw8 - EE 101 Prof A El Gamal Handout 24 March 6 2003...

This preview shows pages 1–2. Sign up to view the full content.

EE 101 Handout # 24 Prof. A. El Gamal March 6, 2003 Homework Assignment #8 Due: Thursday 3/13 1. Defibrillators. A defibrillator is used to deliver a strong shock across the chest of a person in cardiac arrest or fibrillation. The shock contracts all the heart muscle, whereupon the normal beating can (hopefully) start again. The first defibrillators used the simple circuit shown below. v s R th = 10kΩ R chest = 500Ω C = 20 μ F S D With the switch in the standby mode, indicated as ‘S’, the 20 μ F capacitor is charged up by a power supply represented by a Thevenin voltage v s and Thevenin resistance R th = 10kΩ. When the switch is thrown to ‘D’ (for ‘defibrillate’), the capacitor discharges across the patient’s chest, which we represent (pretty roughly) as a resistance of 500Ω. (The connections are made by two ‘paddles’ pushed against the sides of the chest.) On most defibrillators you can select the ‘dose,’ i.e. , total energy of the shock, which is usually between 100J and 400J. (a) Find v s so that the dose is 100J. You can assume the capacitor is fully charged when the switch is thrown to ‘D’. We’ll use this value of v s in parts 1b, 1c, and 1d. (b) How long after the switch is thrown to ‘D’ does it take for the defibrillator to deliver 90% of its total dose, i.e. , 90J? (c) What is the maximum power p max dissipated in the patient’s chest during defib- rillation? (d) Our model of the chest as a resistance of 500Ω is pretty crude. In fact the resistance varies considerably, depending on, e.g. , skin thickness. Suppose that the chest resistance is 1000Ω instead of 500Ω and the value of v s found in part (a) is used. What is the total energy E dissipated in the patient during defibrillation?

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.

{[ snackBarMessage ]}