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Problem 1: Suppose you have a 195 μF capacitor. What charge is stored in it when 118 V is applied to it, in millicoulombs? Q = Problem 2: Suppose you have a 4.25 μF capacitor. Calculate the voltage, in volts, applied to it when the capacitor holds 3.8 μC of charge. V = Problem 3: Suppose you wanted to store 21 μC of charge in a capacitor across a voltage of 120 V. What capacitance is needed in nF? C = Problem 7: A parallel plate capacitor has a charge on one plate of q = 1.5E-07 C. Each square plate is d1 = 1.1 cm wide and the plates of the capacitor are separated by d2 = 0.55 mm. The gap is filled with air, εo = 8.85 × 10-12 C2/Nm2. Part (a) What is the voltage between the plates, ΔV, in V? ΔV = Part (b) What plate width would double this voltage, in centimeters? d3 = Problem 8: Suppose you have the 7.75 μF capacitor of a heart defibrillator at a potential difference of 16.5 × 104 V. Part (a) What is the energy stored in it in J? U = Part (b) Find the amount of stored charge in mC. Q = Problem 9: In open heart surgery, a small amount of energy is often used to defibrillate the heart. Part (a) What voltage, in kilovolts, is applied to the 8.5 μF capacitor of a heart defibrillator that stores 39.5 J of energy? V = Part (b) Find the amount of stored charge, in millicoulombs. Q = Problem 10: A current of 77 μA passes through a wire. Part (a) Express the charge Q passing through the wire in terms of the current I and the time interval Δt. Q = Part (b) In a time interval of Δt = 55 s, how much charge has passed through the wire in μC? Q = Problem 11: A charge of Q = 2.4 C passes through a wire every t = 4.5 s. Part (a) Input an expression for the current, I, in the wire. I = Part (b) What is the current in amperes? I = Part (c) What is the current, in milliamps? I = Problem 12: Suppose you have a pocket calculator through which 2.75 C of charge passes in 2.5 h? What is the average current in milliamperes produced by the solar cells of the pocket calculator? I = Problem 13: Suppose a static charge of 0.27 μC moves from your finger to a metal doorknob in 1.25 ms. What is the current, in amperes? I = Problem 14: A large lightning bolt is observed to have a 22000 A current and move 31 C of charge. What was its duration, in milliseconds? Δt = Problem 15: A cell phone battery uses chemistry to create a charge separation between the terminals (anode and cathode). Such a battery is listed as having a capacity of Q = 3.5E-08 C. Part (a) If this charge separation consisted entirely of free electrons, how many free electrons would be present in the battery? N = Part (b) If the operation of the cellphone requires that 1.6 million electrons move through the circuit every second, how long will a full charge of the battery last, in seconds? t = Part (c) What current I, in amperes, is passing through the phone? I = Problem 16: The 220 A current through a spark plug moves 0.45 mC of charge. How long does the spark last, in microseconds? Δt = Problem 17: A current of 9.72AA flows through a wire. How many electrons flow past a particular point in the wire every 8 seconds? nene = Problem 1: A car battery has a voltage of ε = 12 V. To turn the starter on a car the battery must supply I = 344 A. It takes t = 1.8 s for the engine to start. Part (a) Input an expression for the total charge passed through the starter, Q. Q = Part (b) How much energy did the starter consume, E, in J? E = Problem 2: A current of 41 μA passes through a wire. Part (a) Express the charge Q passing through the wire in terms of the current I and the time interval Δt. Q = Part (b) In a time interval of Δt = 79 s, how much charge has passed through the wire in μC? Q = Problem 3: A current of I = 8.4 A is passing through a conductor with cross sectional area A= 8.5 × 10-4 m2. The charge carriers in the conductor, electrons, have a number density n = 9.9 x 1027 m-3. Part (a) Express the charge Q passing through the wire in terms of the current I and the time interval Δt. Q = Part (b) Calculate the numerical value of v, in m/s. vd = Problem 4: A charge of Q = 2.1 C passes through a wire every t = 6.5 s. Part (a) Input an expression for the current, I, in the wire. I = Part (b) What is the current in amperes? I = Part (c) What is the current, in milliamps? I = Problem 5: The 225 A current through a spark plug moves 0.325 mC of charge. How long does the spark last, in microseconds? Δt = Problem 7: An extension cord has a resistivity of ρ = 7.5 × 10-8 Ω⋅m. The cord is made from copper wire with a diameter D = 0.45 cm and it is L = 5.7 m long. Part (a) What is the resistance in ohms? R = Part (b) If a current of I = 3.05 A passes through the wire what voltage is the cord connected to, in volts? V = Problem 8: Suppose you have a 2.9 V flashlight. What current, in amperes, flows through the bulb of the flashlight when its resistance is 3.95 Ω? I = Problem 9: Suppose an indicator light on a DVD player has a resistance of 132 Ω. How many volts are supplied to operate it, given that 21 mA passes through it? V = Problem 10: A battery supplies a constant current of I = 8 mA to the circuit of a flashlight with a resistance of R = 4.1 kΩ. Part (a) Input an expression for the potential difference across the terminals of the battery, ΔV. ΔV = Part (b) What is this potential difference in volts? ΔV = Part (c) Keeping the resistance the same, if the flashlight battery has a potential difference of ΔV = 7.5 V, how much current flows through the circuit, in amperes? I = Problem 11: Consider a wire made of copper with conductivity 6.0 × 107 Ω-1m-1, which has a circular cross-section of radius 0.41 mm. In a particular circuit, this wire carries a current of 1.5 A. Part (a) What is the electric field, in volts per meter, inside this wire? E = Part (b) If we replace this wire with a gold one of the same size, with conductivity 4.1 × 107 Ω-1m-1, what will the electric field in the wire be? E = Problem 12: A light bulb has resistance of R = 110 Ω and has a current of I = 1.85 A passing through it. Part (a) Express the power P using the variables I and R. P = Part (b) Calculate the numerical value of P in W. P = Problem 13: A battery with terminal voltage ΔV = 2.6 V contains E = 2.1 kJ of energy. It is connected to a P = 8.5 W light bulb. Part (a) Input an expression for the light bulb's resistance, R. R = Part (b) What is the resistance, in ohms? R = Part (c) Assuming the voltage remains constant how long will the battery last in seconds? t = Problem 14: A lightning bolt strikes a tree, moving 17.5 C of charge through a potential difference of 0.95 × 102 MV. What energy is dissipated, in joules? E =