Electric Circuit Fundamentals
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Questions and Answers

What is the formula for applying Ohm's law to the entire circuit?

  • R=VI
  • I=R/V
  • I=VR
  • V=IR (correct)
  • What is the formula for the total resistance of the combination of resistors joined in series?

  • Rs = R1 + R2 + R3 (correct)
  • Rs = R1 / R2 / R3
  • Rs = R1 × R2 × R3
  • Rs = R1 - R2 - R3
  • What is the total resistance of the circuit in the example problem?

  • 6 Ω
  • 20 Ω
  • 24 Ω (correct)
  • 4 Ω
  • What is the voltage across the electric lamp and conductor in the example problem?

    <p>6 V</p> Signup and view all the answers

    What is the current through the circuit in the example problem?

    <p>0.25 A</p> Signup and view all the answers

    What is the formula used to calculate the current through the circuit?

    <p>I = V/Rs</p> Signup and view all the answers

    What is the resistance of the electric lamp in the example problem?

    <p>20 Ω</p> Signup and view all the answers

    What is the total potential difference across the two terminals of the battery in the example problem?

    <p>6 V</p> Signup and view all the answers

    What gases are usually used to fill bulbs to prolong the life of the filament?

    <p>Nitrogen and argon</p> Signup and view all the answers

    What is the primary function of a fuse in electric circuits?

    <p>To protect circuits and appliances from excessive current</p> Signup and view all the answers

    What is the characteristic of the metal or alloy used to make a fuse wire?

    <p>Low melting point</p> Signup and view all the answers

    What is the unit of electric power?

    <p>Watt</p> Signup and view all the answers

    What is the rate at which electric energy is consumed in an electric circuit?

    <p>Electric power</p> Signup and view all the answers

    Why is a 5 A fuse used for an electric iron that consumes 1 kW electric power?

    <p>Because it matches the calculated required current</p> Signup and view all the answers

    What is the term used to describe the rate of doing work?

    <p>Power</p> Signup and view all the answers

    What is the effect of excessive current flowing through a fuse wire?

    <p>It melts the fuse wire and breaks the circuit</p> Signup and view all the answers

    What is the direction of electric current in a circuit?

    <p>From the positive terminal to the negative terminal</p> Signup and view all the answers

    What is the unit of electric current?

    <p>Ampere</p> Signup and view all the answers

    What is the formula to calculate the amount of electric charge?

    <p>Q = It</p> Signup and view all the answers

    What is the amount of electric charge that flows through the circuit in the example?

    <p>300 C</p> Signup and view all the answers

    What is the average speed of electrons in a conductor?

    <p>Average drift speed</p> Signup and view all the answers

    How do electrons move in a perfect solid crystal?

    <p>Smoothly and easily</p> Signup and view all the answers

    What is the role of the plug key in the circuit?

    <p>To disconnect the circuit</p> Signup and view all the answers

    What is the purpose of an ammeter in the circuit?

    <p>To measure the current</p> Signup and view all the answers

    What is the order of the drift speed of electrons in a typical copper wire carrying a small current?

    <p>1 mm s-1</p> Signup and view all the answers

    Why does an electric bulb light up immediately when we turn the switch on?

    <p>Because the electric potential difference sets the charges in motion in the conductor</p> Signup and view all the answers

    What is necessary for the flow of charges in a conducting metallic wire?

    <p>Electric potential difference</p> Signup and view all the answers

    What generates the potential difference across the terminals of an electric cell?

    <p>Chemical action</p> Signup and view all the answers

    What is the role of gravity in the flow of charges in a conducting metallic wire?

    <p>It has no role to play</p> Signup and view all the answers

    What is the purpose of a battery in a conducting circuit?

    <p>To generate electric potential difference</p> Signup and view all the answers

    What is the analogy used to describe the flow of charges in a conducting metallic wire?

    <p>Flow of water</p> Signup and view all the answers

    What happens when a cell is connected to a conducting circuit element?

    <p>The electric potential difference sets the charges in motion</p> Signup and view all the answers

    What is the potential difference across the resistor when the current is 2.0 A?

    <p>6.7 V</p> Signup and view all the answers

    A 12 V battery is connected across an unknown resistor, and a current of 2.5 mA flows. What is the resistance of the resistor?

    <p>4.8 Ω</p> Signup and view all the answers

    A battery of 9 V is connected in series with resistors of 0.2 Ω, 0.3 Ω, 0.4 Ω, 0.5 Ω, and 12 Ω, respectively. What is the current that would flow through the 12 Ω resistor?

    <p>0.5 A</p> Signup and view all the answers

    How many 176 Ω resistors are required to carry 5 A on a 220 V line?

    <p>4</p> Signup and view all the answers

    How can three resistors, each of resistance 6 Ω, be connected to have a resistance of 9 Ω?

    <p>Two in parallel and one in series</p> Signup and view all the answers

    Several electric bulbs are rated 10 W and are designed to be used on a 220 V electric supply line. What is the maximum number of lamps that can be connected in parallel with each other across the two wires of 220 V line if the maximum allowable current is 5 A?

    <p>20</p> Signup and view all the answers

    A hot plate of an electric oven connected to a 220 V line has two resistance coils A and B, each of 24 Ω resistance, which may be used separately, in series, or in parallel. What is the current in the parallel case?

    <p>10 A</p> Signup and view all the answers

    Two lamps, one rated 100 W at 220 V, and the other 60 W at 220 V, are connected in parallel to electric mains supply. What is the total current drawn from the line if the supply voltage is 220 V?

    <p>1.5 A</p> Signup and view all the answers

    Study Notes

    Electric Circuits and Current

    • Electric current flows in a circuit from the positive terminal of the cell to the negative terminal through the circuit components (e.g., bulb and ammeter).
    • A schematic diagram of an electric circuit consists of a cell, electric bulb, ammeter, and plug key.

    Electric Charge and Flow

    • The flow of electric charge is similar to the flow of water, requiring a pressure difference (electric potential difference) to occur.
    • In a conducting metallic wire, electrons move only if there is a potential difference along the conductor.
    • The potential difference is produced by a battery, which generates a potential difference across its terminals even when no current is drawn.

    Electric Current and Drift Speed

    • The motion of electrons in a conductor is different from that of charges in empty space.
    • When a steady current flows through a conductor, the electrons move with a certain average drift speed, which is very small (e.g., 1 mm s-1 in a typical copper wire).

    Electric Potential and Potential Difference

    • Electric potential difference (or voltage) is the driving force behind electric current flow.
    • Applying Ohm's law to the entire circuit, we have V = IR, where V is the potential difference, I is the current, and R is the resistance.

    Resistors in Series

    • When several resistors are connected in series, the total resistance of the combination (Rs) equals the sum of their individual resistances (R1, R2, R3, etc.).
    • The total resistance of the combination is greater than any individual resistance.

    Electric Power and Energy

    • Electric power is the rate of consumption of energy, which is also the rate at which electric energy is dissipated or consumed in an electric circuit.
    • The values of current I flowing in a given resistor for the corresponding values of potential difference V across the resistor can be used to plot a graph and calculate the resistance of the resistor.

    Applications of Electric Circuits

    • Electric lamps are usually filled with chemically inactive nitrogen and argon gases to prolong the life of the filament.
    • Joule's heating is used in fuses, which protect circuits and appliances by stopping the flow of any unduly high electric current.
    • Electric power is used in various applications, such as electric irons, which consume a certain amount of power when operated at a specific voltage.

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    Description

    This quiz covers the basics of electric circuits, including the flow of electric current and the components of a circuit. Test your understanding of electric circuits and their components.

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