1:A defibrillator sends a7.5A current through the chest of a patient by applying a12000V voltage as in the figure. What is the resistance of the path in k? 2:During open-heart surgery, a defibrillator can be used to bring a patient out of cardiac arrest During such a procedure, the resistance of the path is 550 and a 12.5 mA current is needed. What voltage should be applied in V? Problem 3: A cell phone battery uses chemistry to create charge separation between the terminals (anode and cathode). Such a battery is listed as having a capacity of Q = 9.5E-08 C.

Randomized Variables Q = 9.5E-08 C % Part (a) How many free electrons does the battery contain, N? Problem 4: Suppose an indicator light on a DVD player has a resistance of 134 . How many volts are supplied to operate it, given that 26 mA passes through it? Problem 5:A high-voltage electricity transmission line is hung from metal towers with glass insulators having a resistance of0.95 10⁹ each. Randomized VariablesR=0.95 10⁹ V=205kV What current, in milliamperes, flows through an insulator if the voltage is 205 kV? 6. Use the table below to answer the following question.

Suppose a resistor's resistance is 40.0% greater at 100C than at 20.0C ? Of what material is the resistor made? 7. Use the table below to answer the following questions. Suppose a wire has a length of 26.1m with a diameter of 0.117mm .If the wire described in the problem statement has a resistance of 78.3 at 20.0C , then what is the resistivity, in ohm meters, of the material from which the wire was made? 8. Digital medical thermometers determine temperature by measuring the resistance of a semiconductor device called a thermistor, which has a temperature coefficient of resistivity of = 0.0600 (C)-1, after it has reached thermodynamic equilibrium with the patient. What is a patient's temperature, in degrees Celsius, if the thermistor's resistance at that temperature is 80.5 % of its value at 37.0C (which is normal body temperature)? Problem 9: The strip of solar cells just above the keys of a calculator convert light to electricity to supply its energy needs. A charge of 4.00 C passes through the calculator's solar cells in 4.00 h. What is the average power output in W, given the calculator's voltage output is 3.3 V? Problem 10: An electric water heater consumes 2.5 kW for 2.25 h per day. What is the cost (in $) of running it for one year if electricity costs 15 cents/kWh? 11. A cauterizer, used to stop bleeding in surgery, supplies 1.85 mA at 15.5 kV. What is its power output, P, in watts? Problem 12: A North American tourist takes his 25.0 W, 120 V AC razor to Europe, finds a plug adapter, and plugs it into 240 V AC. Assuming constant resistance, what power, in watts, does the razor consume as it is ruined? Problem 13: Consider a 1.4 kW short circuit through a 0.125 resistance. What voltage is involved in the short circuit, in volts? Problem 14: While taking a bath, a person touches the metal case of a radio. The path through the person to the drainpipe and ground has a resistance of 4100 .

Randomized Variables R = 4100 What is the smallest rms voltage on the case of the radio that could cause ventricular fibrillation in V, assuming ventricular fibrillation can initiate at Irms = 100 mA. roblem 15: As shown, three resistors are connected to a voltage source such that the resistors R2 and R3 are in parallel with one another, and that parallel combination is in series with resistor R1 and the voltage source. Resistance values and the potential of the voltage source are as indicated in the figure.

Calculate the current, I3 , in amperes, that passes through resistor R3 16. Consider the circuit in the following diagram, where the resistances are R1 = 0.45R, R2 = 4R, R3 = 0.85R, and R4 = 3R, where R = 23 . The circuit is connected to a V = 4.2 V source. .Input an expression for the equivalent resistance of the circuit in terms of R1, R2, R3, and R4. Problem 17: Consider a circuit shown in the figure. Ignore the internal resistances of the batteries.

Randomized Variables 1 = 48 V 2 = 46 V R1 = 7 R2 = 10 R3 = 4 . Express the current I1 going through resistor R1 in terms of the currents I2 and I3 going through resistors R2 and R3. Use the direction of the currents as specified in the figure. Problem 18: If you try and measure the voltage of a battery with a voltmeter connected in series, you won't get a completely accurate measurement because of the internal resistance of the battery. To see how large this effect is, consider trying to measure the terminal voltage of a 1.585 V alkaline cell having an internal resistance of 54 by placing a 0.95 k voltmeter across its terminals.

Randomized Variables R = 0.95 k r = 54 What current flows in A? Problem 19: A heart pacemaker fires 65 times a minute, each time a 25.0 nF capacitor is charged (by a battery in series with a resistor) to 0.632 of its full voltage.

Randomized Variables s = 65 times per minutes What is the value of the resistance in ? Problem 20: An uncharged capacitor with C = 67 F and a resistor with R = 95 are connected in series with a battery of = 3.5 V.

Randomized Variables C = 67 F R = 95 = 3.5 V Express the time constant in terms of R and C. 21. The figures below demonstrate four current-voltage characteristics of different resistors. Which of them demonstrates Ohmic behavior? 1 and 4 4 1, 2, 4 3 1 and 2 2 and 4 Problem 22: A circuit is created with a constant voltage source, a resistor and an ammeter. A second resistor is added using a rectangular block of conducting material with side lengths a < b < c, and the current is measured with the block connected in three different orientations as shown below. Which statement about the resulting current in the circuit is true? The current is greatest in the circuit on the left and least in the circuit on the right. The current is greatest in the circuit in the center and least in the circuit on the left. The current is greatest in the circuit on the right and least in the circuit in the center. The current is the same in all three circuits. The current is greatest in the circuit on the right and least in the circuit on the left. Problem 23: Consider three electric bulbs. Voltage drop across bulb #1 is V and current passing through it is I. Voltage drop across bulb #2 is 2V with current passing through it I/4. Voltage drop across bulb #3 is V/8 and current passing through it is 4I. Which bulb produces the greatest illumination? Bulb #1 because of the greatest power dissipated. Bulb #2 because it has greatest voltage drop. Bulb #3 because it has greatest current. It is impossible to answer without resistances of bulbs given. Problem 24: Three identical resistors are connected in series to an ideal battery of 12 V. The current which flows through the battery is measured to be 1 A. Which statement is true about this situation? Each resistor has resistance of 4 Ohm. The power dissipated in each resistor is 4W. The voltage drop on each resistor is 4V. All of these statements are true. The current through each resistor is 1A. Problem 25: Consider the circuit shown in the picture. It consists of three identical resistors, an ideal battery, and a switch S. Answer the following questions about what happens after you close the switch." After closing switch S, the total resistance of the circuit: Increases Decreases Stays the same part (b) After closing switch S, the voltage drop across resistor 2: Part (c) After closing switch S, current through resistor 2: Part (d) After closing the switch S, current through resistor 1: Part (e) After closing the switch S, voltage drop across resistor 1: Part (f) After closing the switch S, current through the battery: Part (g) After closing the switch S, the total power dissipated in the circuit: Part (h) After closing the switch S, the power dissipated in resistor 1: part (I) After closing the switch S, the power dissipated in resistor 2: Problem 26: The excess charge at a given point in a circuit as a function of time is described by the equation q(t) = 2.5 - 2.5t + 2.9t2,

where the charge is in coulombs when the time is in seconds. Calculate the instantaneous current, in amperes, that flows through the circuit at time t1 = 8.5 s. Problem 27: A solid conical frustum has a length L = 26 cm, an initial radius R1 = 6.5 mm and a final radius R2 = 10.5 mm. The material that it is made from has a resistivity = 1.3 10-5 m. Integrate over the length of the frustum to write equation for the resistance of the frustum in terms of L, R1, R2, and . Problem 28: The circuit shown contains a voltage source with emf =8.99V , a resistor with resistance R=135k , and a capacitor with capacitance C=662nF . When switch S is set to position a , the three circuit elements are in series. When the switch is in position b , the battery is excluded from the circuit. The switch is initially moved to position a where it remains for a sufficiently long time that the capacitor is fully charged. Calculate the maximum charge, in coulombs, on the capacitor. Part (b) The switch is moved from position a , but it is not connected to position b , so the circuit not a complete circuit. What will happen to the voltage across the capacitor? Part (c) The switch is now moved to position b . What is the magnitude of the instantaneous current, in amperes, through resistor at the instant the switch makes contact with terminal b ? Part (d) With time measured from the instant that switch S is closed in position b , enter an expression for the voltage across the capacitor as a function of time. Part (e) With time measured from the instant that switch S is closed in position b , calculate the time, in seconds, when the charge on the capacitor is one-half of its maximum value. Part (f) Calculate the current through the resistor, in amperes, at time t=95.5ms after the switch is closed in position b .