Physics Chapter on Circuits and Power
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Physics Chapter on Circuits and Power

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Questions and Answers

If the distance between two electric charges doubles, how does the force they exert on each other change?

  • 2 times as large
  • 1/2 as large
  • 4 times as large
  • 1/4 as large (correct)

    • What happens when you hold two pieces of tape together after pulling them off a window?

  • Repel because they have like charges (correct)
  • Attract because they have opposite charges
  • Repel because they have opposite charges
  • Attract because they have like charges

    • Which of the following correctly defines resistance in an electrical circuit?

  • R = P/I
  • R = V/I (correct)
  • R = I/V
  • R = V/P

    • What is the relationship between electric power, current, and voltage?

    <p>P = IV</p> Signup and view all the answers

    Which formula represents the electric field in relation to voltage?

    <p>E = -∇V</p> Signup and view all the answers

    What is the value of Coulomb’s constant, k?

    <p>8.988 · 10^9 N m²/C²</p> Signup and view all the answers

    What is the unit of electric field strength?

    <p>V/m</p> Signup and view all the answers

    If the voltage is doubled while resistance remains constant, what happens to the current?

    <p>It doubles</p> Signup and view all the answers

    What will happen if you switch on the flashlight assuming good contact with the terminals?

    <p>It will not work because the batteries cannot send current backward.</p> Signup and view all the answers

    Which battery in the flashlight arrangement will run out of chemical potential energy first?

    <p>The first battery will run out first.</p> Signup and view all the answers

    What occurs when one wire in the desk lamp's cord is completely cut?

    <p>No current will flow through the bulb.</p> Signup and view all the answers

    When both toasting units of a toaster are operated, how much power do the wires waste?

    <p>About 4 W.</p> Signup and view all the answers

    What is the power loss as heat in a power line carrying 10 A with a resistance of 2 Ω?

    <p>$200 W$</p> Signup and view all the answers

    What will happen to the current through the toaster when two units are operated simultaneously?

    <p>The current will double to 10 A.</p> Signup and view all the answers

    If a flashlight's battery is arranged in series, which effect is observed?

    <p>The total voltage increases.</p> Signup and view all the answers

    What will lead to the light bulb in a damaged desk lamp glowing brightly?

    <p>Replacing the cut wire.</p> Signup and view all the answers

    What causes the paper to stick to the comb?

    <p>The paper becomes electrically polarized.</p> Signup and view all the answers

    What type of objects can a charged object repel?

    <p>Neutral objects but not neutral particles.</p> Signup and view all the answers

    What effect does polarization have on the potential energy of a system?

    <p>Minimizes the potential energy of a system.</p> Signup and view all the answers

    How do sharpened metal rods on a commercial jet prevent electric charge accumulation?

    <p>By transferring any charge on the plane to the air behind the plane.</p> Signup and view all the answers

    Why can't an electric current flow through a piece of glass?

    <p>Electrons in the glass are tightly bound to their atoms and cannot transport charge.</p> Signup and view all the answers

    What could cause a light to keep going out despite having a good bulb?

    <p>Either an open circuit or a short.</p> Signup and view all the answers

    What is the main advantage of transmitting electric power across long distances using low current?

    <p>Electric power lost in the wires is greatly reduced.</p> Signup and view all the answers

    What happens when you turn both batteries around and reinsert them into a working flashlight?

    <p>The flashlight will not work at all.</p> Signup and view all the answers

    Which options represent possible changes to a typical bar magnet's magnetic poles?

    <p>Only remove its magnetic poles altogether and reverse its magnetic poles</p> Signup and view all the answers

    What would happen to a bar magnet if placed in a coil experiencing a pulse of alternating current?

    <p>The poles would reverse rapidly and the magnetization would depend on current at shutdown</p> Signup and view all the answers

    What is a possible reason for a strong permanent magnet's field to decrease?

    <p>Both having overheated and being hit hard</p> Signup and view all the answers

    Why is a steel refrigerator door not permanently magnetic?

    <p>All the magnetic domains are oriented randomly</p> Signup and view all the answers

    If a bar magnet is placed in a coil and subjected to a pulse of current, which type of current is likely to be used for effective magnetization?

    <p>Direct current (DC)</p> Signup and view all the answers

    What is the effect on a bar magnet if it is subjected to rapid changes in magnetic polarity?

    <p>It will become magnetically unstable</p> Signup and view all the answers

    What is the role of the pulse of current when magnetizing a bar of metal?

    <p>It causes magnetic domains to align in one direction</p> Signup and view all the answers

    In a typical bar magnet that is magnetized, what feature distinguishes the north and south poles?

    <p>The direction of the magnetic field line</p> Signup and view all the answers

    What is the equation for finding the angular momentum?

    <p>L = Iω</p> Signup and view all the answers

    What does the variable 'g' represent in the equation for gravitational force?

    <p>The acceleration due to gravity</p> Signup and view all the answers

    Which of these is the correct formula for rotational kinetic energy?

    <p>K = Iω^2</p> Signup and view all the answers

    What is the formula for calculating work done by a force?

    <p>W = Fk∆x</p> Signup and view all the answers

    How is angular acceleration defined in relation to linear acceleration?

    <p>α = a/r</p> Signup and view all the answers

    What is the equation for the period of oscillation in a pendulum?

    <p>T = 2π√(L/g)</p> Signup and view all the answers

    Which equation correctly expresses the relationship between impulse and momentum?

    <p>∆p = F∆t</p> Signup and view all the answers

    If a spring has a constant 'k', what is the formula for the elastic potential energy stored in it?

    <p>U = (1/2)kx^2</p> Signup and view all the answers

    What does the term 'moment of inertia' refer to in rotational motion?

    <p>The resistance to angular acceleration</p> Signup and view all the answers

    Which of the following represents the relationship between frequency and period?

    <p>f = 1/T</p> Signup and view all the answers

    How is static friction characterized in terms of applied force?

    <p>F_static friction = -F_applied if F_applied ≤ µ_static F_support</p> Signup and view all the answers

    What does the equation $c = λf$ represent in wave motion?

    <p>Relationship between wave speed, wavelength, and frequency</p> Signup and view all the answers

    Which equation represents the conservation of linear momentum?

    <p>p_initial = p_final</p> Signup and view all the answers

    Study Notes

    Flashlight Circuit

    • A flashlight circuit requires a closed loop for current flow.
    • Electrons are the charge carriers in a circuit.
    • Batteries provide chemical energy to power the circuit.

    Batteries Depletion

    • Batteries connected in series share the total voltage equally.
    • All batteries in a series circuit will deplete at the same rate.

    Damaged Desk Lamp

    • If one wire in a two-wire cord is cut, the circuit is broken.
    • No current will flow through the bulb, and it will not light up.

    Toaster Power Consumption

    • Power consumption is directly proportional to current flowing through the circuit.
    • Doubling current through a circuit results in a quadrupled power loss.

    Power loss in power line

    • The power loss in a power line is calculated by P=I^2*R, where P is power, I is current, and R is resistance.
    • A power line carrying 10 amps with a resistance of 2 ohms will lose 200 watts of power as heat.

    Magnetic Pole Properties

    • A bar magnet has a north pole and a south pole.
    • The magnetic poles can be reversed, but not removed or converted to the same polarity.

    Magnet Manufacturing

    • Bar magnets are magnetized by exposing them to a strong magnetic field.
    • This field is usually generated by a coil carrying direct current (DC).

    Magnet Demagnetization

    • Permanent magnets can be demagnetized if they are heated or physically impacted.
    • This is due to the realignment of magnetic domains within the magnet.

    Steel Refrigerator Door

    • Steel refrigerator doors are not permanently magnetic because their magnetic domains are randomly oriented.
    • This means there is no net magnetic field.

    Magnetic Field and Pole Strength

    • The magnetic field strength in a coil is a measure of the magnetic force it produces.
    • Steel rods with a pole strength are susceptible to magnetic forces.

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    Description

    This quiz covers essential concepts in circuit theory, including the behavior of flashlight circuits, battery functionality in series, and the effects of current on power consumption. It also explores power loss in electrical lines and characteristics of magnetic poles.

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