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physics21

[PHYS] Example Question: In Niels Bohr's 1913 model of the atom, the electron is in a circular orbit around a nucleus. An electron is 5.40 10-11 m from a nucleus traveling in a circular orbit with a speed of 2.50 106 m/s. Example Question # Question In Niels Bohr's 1913 model of the atom, the electron is in a circular orbit around a nucleus. An electron is 5.40*10^(-11) m from a nucleus traveling in a circular orbit with a speed of 2.50*10^6 m/s. What is the magnitude of the magnetic moment due to the electron's motion? # Explanation What is the magnitude of the magnetic moment due to the electron's motion? 2022. 6. 20.
[PHYS] Example Question: For the circuit shown below, the ideal voltmeter reads 5.30 V and the ideal ammeter reads 2.60 mA. Find the following. Example Question # Question For the circuit shown below, the ideal voltmeter reads 5.30 V and the ideal ammeter reads 2.60 mA. Find the following. # Explanation 2022. 6. 20.
[PHYS] Example Question: In the circuit of the figure below, the switch S has been open for a long time. It is then suddenly closed. Take e m f = 10.0 V, R1 = 42.0 kΩ, R2 = 120 kΩ, and C = 12.0 𝜇F. Example Question # Question In the circuit of the figure below, the switch S has been open for a long time. It is then suddenly closed. Take E = 10.0 V, R1 = 42.0 kΩ, R2 = 120 kΩ, and C = 12.0 𝜇F. Determine the time constant before the switch is closed. Determine the time constant after the switch is closed. Let the switch be closed at t = 0. Determine the current in the switch as a function of .. 2022. 6. 20.
[PHYS] Example Question: A battery with e m f = 2.00 V and no internal resistance supplies current to the circuit shown in the figure below. When the double-throw switch S is open as shown in the figure, the current in the battery is 1.01 mA. When the s.. Example Question # Question A battery with E = 2.00 V and no internal resistance supplies current to the circuit shown in the figure below. When the double-throw switch S is open as shown in the figure, the current in the battery is 1.01 mA. When the switch is closed in position a, the current in the battery is 1.21 mA. When the switch is closed in position b, the current in the battery is 2.05 .. 2022. 6. 20.
[PHYS] Example Question: Consider the circuit shown in the figure below. (Let R = 12.0 Ω.) Example Question # Question Consider the circuit shown in the figure below. (Let R = 12.0 Ω.) Find the current in the 12.0-Ω resistor. Find the potential difference between points a and b. # subTitle Find the current in the 12.0-Ω resistor. Find the potential difference between points a and b. 2022. 6. 20.
[PHYS] Example Question: While taking photographs in Death Valley on a day when the temperature is 53.0°C, Bill Hiker finds that a certain voltage applied to a copper wire produces a current of 1.10 A. Bill then travels to Antarctica and applies the sa.. Example Question # Question While taking photographs in Death Valley on a day when the temperature is 53.0°C, Bill Hiker finds that a certain voltage applied to a copper wire produces a current of 1.10 A. Bill then travels to Antarctica and applies the same voltage to the same wire. What current does he register there if the temperature is −88.0°C? Assume that no change occurs in the wire's shap.. 2022. 6. 20.
[PHYS] Example Question: Two capacitors, C1 = 6.06 µF and C2 = 3.22 µF, are connected in parallel, then the combination is connected to a 250 V battery. When the capacitors are charged, each one is removed from the circuit. Next, the two charged capac.. Example Question # Question Two capacitors, C1 = 6.06 µF and C2 = 3.22 µF, are connected in parallel, then the combination is connected to a 250 V battery. When the capacitors are charged, each one is removed from the circuit. Next, the two charged capacitors are connected to each other so that the positive plate of one capacitor is connected to the negative plate of the other capacitor. What is.. 2022. 6. 20.
[PHYS] Example Question: A uniform electric field E = 2550 V/m exists within a certain region. What volume of space contains an energy equal to 1.10 ✕ 10-7 J? Express your answer in cubic meters and in liters. Example Question # Question A uniform electric field E = 2550 V/m exists within a certain region. What volume of space contains an energy equal to 1.10 ✕ 10-7 J? Express your answer in cubic meters and in liters. # Explanation 2022. 6. 20.
[PHYS] Example Question: A nonconducting sphere has mass 80.8 g and radius 19.8 cm. A flat, compact coil of wire with seven turns is wrapped tightly around it, with each turn concentric with the sphere. The sphere is placed on an inclined plane that slo.. Example Question # Question A nonconducting sphere has mass 80.8 g and radius 19.8 cm. A flat, compact coil of wire with seven turns is wrapped tightly around it, with each turn concentric with the sphere. The sphere is placed on an inclined plane that slopes downward to the left (see figure below), making an angle 𝜃 with the horizontal so that the coil is parallel to the inclined plane. A unifo.. 2022. 6. 20.
[PHYS] Example Question: The upper portion of the circuit in the figure below is fixed. The horizontal wire at the bottom has a mass of 10.0 g and is 5.00 cm long. This wire hangs in the gravitational field of the Earth from identical light springs conn.. Example Question # Question The upper portion of the circuit in the figure below is fixed. The horizontal wire at the bottom has a mass of 10.0 g and is 5.00 cm long. This wire hangs in the gravitational field of the Earth from identical light springs connected to the upper portion of the circuit. The springs stretch 0.540 cm under the weight of the wire, and the circuit has a total resistance o.. 2022. 6. 20.
[PHYS] Example Question: A particle with positive charge q = 3.84 10-18 C moves with a velocity v with arrow = (5î + 4ĵ − k) m/s through a region where both a uniform magnetic field and a uniform electric field exist. Example Question # Question A particle with positive charge q = 3.84*10^-(18) C moves with a velocity v with arrow = (5î + 4ĵ − k) m/s through a region where both a uniform magnetic field and a uniform electric field exist. # Explanation A particle with positive charge q = 3.84*10^-(18) C moves with a velocity v with arrow = (5î + 4ĵ − k) m/s through a region where both a uniform magnetic field .. 2022. 6. 20.
[PHYS] Example Question: A typical magnitude of the external magnetic field in a cardiac catheter ablation procedure using remote magnetic navigation is B = 0.080 T. Suppose that the permanent magnet in the catheter used in the procedure is inside the l.. Example Question # Question A typical magnitude of the external magnetic field in a cardiac catheter ablation procedure using remote magnetic navigation is B = 0.080 T. Suppose that the permanent magnet in the catheter used in the procedure is inside the left atrium of the heart and subject to this external magnetic field. The permanent magnet has a magnetic moment of 0.12 A · m2. The orientatio.. 2022. 6. 20.
[PHYS] Example Question: In the figure below, the cube is 42.4 cm on each edge. Four straight segments of wire—ab, bc, cd, and da—form a closed loop that carries a current I = 5.30 A in the direction shown. A uniform magnetic field of magnitude B = .. Example Question # Question In the figure below, the cube is 42.4 cm on each edge. Four straight segments of wire—ab, bc, cd, and da—form a closed loop that carries a current I = 5.30 A in the direction shown. A uniform magnetic field of magnitude B = 0.022 T is in the positive y direction. Determine the magnetic force on each segment. ab bc cd da # Explanation ab bc cd da 2022. 6. 20.
[PHYS] Example Question: A 290-W heating coil designed to operate from 110 V is made of Nichrome wire 0.230 mm in diameter. (Assume 𝜌 = 1.50 10-6 Ω · m, and 𝛼 = 4.000 10-4(°C)−1 for Nichrome.) Example Question # Question A 290-W heating coil designed to operate from 110 V is made of Nichrome wire 0.230 mm in diameter. (Assume 𝜌 = 1.50 * 10^(-6) Ω · m, and 𝛼 = 4.000 * 10^(-4)(°C)^(−1) for Nichrome.) (a) Assuming the resistivity of the Nichrome remains constant at its 20.0°C value, find the length of wire used. (b) Now consider the variation of resistivity with temperature. What power i.. 2022. 6. 20.
[PHYS] Example Question: The cost of energy delivered to residences by electrical transmission varies from $0.070/kWh to $0.258/kWh throughout the United States; $0.110/kWh is the average value. Example Question # Question The cost of energy delivered to residences by electrical transmission varies from $0.070/kWh to $0.258/kWh throughout the United States; $0.110/kWh is the average value. (a) At this average price, calculate the cost of leaving a 40-W porch light on for two weeks while you are on vacation? (b) At this average price, calculate the cost of making a piece of dark toast in.. 2022. 6. 20.
[PHYS] Example Question: The quantity of charge q (in coulombs) that has passed through a surface of area 2.05 cm2 varies with time according to the equation q = 7t^3 + 3t + 6, where t is in seconds. Example Question # Question The quantity of charge q (in coulombs) that has passed through a surface of area 2.05 cm^2 varies with time according to the equation q = 7t^3 + 3t + 6, where t is in seconds. (a) What is the instantaneous current through the surface at t = 0.900 s? (b) What is the value of the current density? # Explanation (a) What is the instantaneous current through the surface at.. 2022. 6. 20.
[PHYS] Example Question: The figure below represents a section of a circular conductor of nonuniform diameter carrying a current of I = 5.40 A. The radius of cross-section A1 is r1 = 0.230 cm. Example Question # Question The figure below represents a section of a circular conductor of nonuniform diameter carrying a current of I = 5.40 A. The radius of cross-section A1 is r1 = 0.230 cm. What is the magnitude of the current density across A1? Specify the radius at A2. Specify the current at A2. Specify the current density at A2. # Explanation What is the magnitude of the current density.. 2022. 6. 20.
[PHYS] Example Question: A 56.0-m length of coaxial cable has an inner conductor that has a diameter of 2.58 mm and carries a charge of 8.10 µC. The surrounding conductor has an inner diameter of 7.27 mm and a charge of −8.10 µC. Example Question # Question A 56.0-m length of coaxial cable has an inner conductor that has a diameter of 2.58 mm and carries a charge of 8.10 µC. The surrounding conductor has an inner diameter of 7.27 mm and a charge of −8.10 µC. (a) What is the capacitance of this cable? (b) What is the potential difference between the two conductors? # Explanation (a) What is the capacitance of this cable? .. 2022. 6. 20.
[PHYS] Example Question: Two identical parallel-plate capacitors, each with capacitance 18.0 𝜇F, are charged to potential difference 47.0 V and then disconnected from the battery. They are then connected to each other in parallel with plates of like .. Example Question # Quesiton Two identical parallel-plate capacitors, each with capacitance 18.0 𝜇F, are charged to potential difference 47.0 V and then disconnected from the battery. They are then connected to each other in parallel with plates of like sign connected. Finally, the plate separation in one of the capacitors is doubled. Find the total energy of the system of two capacitors before t.. 2022. 6. 20.
[PHYS] Example Question: Find the equivalent capacitance between points a and b in the combination of capacitors shown in the figure below. (C1 = 7.0 µF and C2 = 6.0 µF.) Example Question # Question Find the equivalent capacitance between points a and b in the combination of capacitors shown in the figure below. (C1 = 7.0 µF and C2 = 6.0 µF.) # Explanation # Answer A) 15.7 2022. 6. 20.
[PHYS] Example Question: Consider the circuit shown in the figure below, where C1 = 8.00 µF, C2 = 6.00 µF, and ΔV = 22.0 V. Capacitor C1 is first charged by closing switch S1. Switch S1 is then opened, and the charged capacitor is connected to the un.. Example Question # Question Consider the circuit shown in the figure below, where C1 = 8.00 µF, C2 = 6.00 µF, and ΔV = 22.0 V. Capacitor C1 is first charged by closing switch S1. Switch S1 is then opened, and the charged capacitor is connected to the uncharged capacitor by closing S2. Calculate the initial charge (in µC) acquired by C1. Calculate the final charge (in µC) on each capacitor. After.. 2022. 6. 20.
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