PHYS 204 Final Exam Expected Questions and Answers

PHYS 204 Final Exam Expected Questions and Answers What is an application of a Wheatstone bridge? a) charge storage in capacitor b) measure voltage in a voltmeter c) sensor in a light switch d) change frequency in a radio - ANSWER-c) sensor in a light switch In a Wheatstone Bridge: what is the unknown resistor, Rx? R = 6Ω Ra = 4Ω Rb = 2Ω Ig = 0A a) 12 Ω Copyright © KAYLIN 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED FIRST PUBLISH NOVEMBER, 2024 Copyright © Stuvia International BV Page 2/12 b) 3 Ω c) 4 Ω d) 6 Ω - ANSWER-b) 3 Ω If Ig is not zero in a Wheatstone bridge, meaning current is flowing through the galvanometer, which of these is true? a) Rx = R b) Rx R c) R Ra d) Ra Rb - ANSWER-b) Rx R According to the junction rule for the Wheatstone bridge, which of these must be true? (reference picture of Wheatstone bridge in lab manual) a) Ig = Ia + Ib b) Ix = I + Ig c) I = Ia + Ib d) Ib = Ig + Ia - ANSWER-d) Ib = Ig + Ia If you increase the length of a wire in the Wheatstone bridge, what happens to the resistance? Copyright © KAYLIN 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED FIRST PUBLISH NOVEMBER, 2024 Copyright © Stuvia International BV Page 3/12 a) decreases b) increases c) it remains the same d) it depends on the resisitivity - ANSWER-b) increases You have two wires, both are the same length and same diameter. However, one is copper wire (p = 1.7E- 8 Ωm) and the other is nickel-silver wire (p = 28E-8. Ωm). Which wire has the greater resistance? - ANSWER-Nickel-silver wire For the Wheatstone bridge, what element has the unknown resistance? a) a slidewire b) a resistor c) a galvanometer d) a spool of wire - ANSWER-d) a spool of wire What does it say when the Wheatstone bridge is balanced? a) There is no current running through the slide-wire. b) The current running through the top of the bridge is equal to the current in the bottom (I = Ia). c) There is no current running through the top of the bridge (R and Ra). Copyright © KAYLIN 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED FIRST PUBLISH NOVEMBER, 2024 Copyright © Stuvia International BV Page 4/12 d) There is no current running through the middle (Ig = 0). - ANSWER-d) There is no current running through the middle (Ig = 0). A balanced slide-wire Wheatstone bridge has the following properties: La = 40cm, Lb = 60cm, and R = 20Ω. What is the unknown resistance, Rx? (refer to lab manual for equation) - ANSWER-Rx = 30Ω In the Tangent Galvanometer lab, what were we trying to measure? - ANSWER-The Earth's magnetic field A coil of wire is laid flat on a table. A current is passed through the wire in a clockwise direction. What is the direction of the induced magnetic field? a) Counterclockwise b) Clockwise c) Out of the table d) Into the table - ANSWER-d) Out of the table If you increase the diameter of a loop of wire, what will happen to the strength of the induced magnetic field? a) Increase b) Decrease Copyright © KAYLIN 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED FIRST PUBLISH NOVEMBER, 2024 Copyright © Stuvia International BV Page 5/12 c) Not affected - ANSWER-b) Decrease The magnetic field induced in a single loop of wire is B = 3 T. If the same wire is looped 3 times into a coil, what will the magnetic field of the coil be? a) 3 T b) 1 T c) 9 T d) 6 T - ANSWER-c) 9 T What is the magnetic field, B, induced in a single loop of wire with a radius of 0.5m by a 2A current? - ANSWER-8πx10-7 T In the lab, when we change the number of loops in the tangent galvanometer coil, what do we expect to happen? a) The radius of the coil changes. b) The direction of the current changes. c) The deflection angle changes. d) The permeability changes. - ANSWER-c) The deflection angle changes. If you move the switch from one side to the other of a double-pole-double-throw switch (going past the middle), which statement best describes what happens in the circuit? Copyright © KAYLIN 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED FIRST PUBLISH NOVEMBER, 2024 Copyright © Stuvia International BV Page 6/12 a) The power goes from on to off. b) The current reverses direction everywhere in the circuit. c) The ammeter switches from reading positive to negative current. d) The current in one loop of the circuit reverses in direction. - ANSWER-d) The current in one loop of the circuit reverses in direction. How should the plane of the coil of a tangent galvanometer by positioned to measure the Earth's magnetic field? - ANSWER-Vertical in the magnetic North-South direction What happens to the compass needle when the current is turned on in the tangent galvanometer? - ANSWER-It moves by some amount depending on the