Electric Current and Ohm's Law Quiz
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Questions and Answers

What is the unit of electric current?

  • Ampere (correct)
  • Watt
  • Volt
  • Ohm

    • According to Ohm's Law, current is directly proportional to which of the following?

  • Mobility
  • Current Density
  • Resistance
  • Potential Difference (correct)

    • What does current density (J) measure?

  • Total current in a conductor
  • Voltage drop across a resistor
  • Average electron velocity
  • Current per unit cross-sectional area (correct)

    • What is the formula for drift velocity (Vd)?

    <p>Vd = I / neA</p> Signup and view all the answers

    What does mobility (µ) represent?

    <p>Ease of electron movement through a material</p> Signup and view all the answers

    What is the relationship between voltage (∆V), current (I), and resistance (R) as per Ohm's Law?

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

    The formula for conductivity (σ) is derived from which concept?

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

    Which of the following represents the average velocity of electrons in a conductor?

    <p>Drift Velocity</p> Signup and view all the answers

    In a Voltage vs Current graph according to Ohm's Law, what does the slope represent?

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

    What does resistivity (ρ) measure?

    <p>Resistance per unit length and area</p> Signup and view all the answers

    What is the correct formula for terminal voltage in terms of emf and internal resistance?

    <p>V = ε - Ir</p> Signup and view all the answers

    In a series combination of cells, how is the equivalent emf calculated?

    <p>εeq = ε1 + ε2</p> Signup and view all the answers

    What is the relationship for equivalent internal resistance in a series combination of cells?

    <p>req = r1 + r2</p> Signup and view all the answers

    What type of resistance is added in series with a galvanometer to convert it to a voltmeter?

    <p>High resistance</p> Signup and view all the answers

    Which feature best describes an ideal voltmeter?

    <p>Has infinite internal resistance</p> Signup and view all the answers

    How do you calculate power dissipated in a resistor?

    <p>P = I^2R</p> Signup and view all the answers

    What happens to the equivalent emf in a parallel combination of cells with the same emf?

    <p>It remains the same</p> Signup and view all the answers

    What is the purpose of a meter bridge?

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

    In the formula R = (100 - l1) * S / l1, what does R represent?

    <p>Unknown resistance</p> Signup and view all the answers

    What is the effect of internal resistance on terminal voltage?

    <p>It decreases the terminal voltage</p> Signup and view all the answers

    What happens to the resistance of a semiconductor as temperature increases?

    <p>Resistance decreases</p> Signup and view all the answers

    Which formula represents the total resistance in a series combination of two resistors?

    <p>$Req = R_1 + R_2$</p> Signup and view all the answers

    According to Kirchhoff's Current Law, how is current defined at a junction?

    <p>I_in is equal to I_out</p> Signup and view all the answers

    What does the equation $E = V + IR$ express in relation to a cell?

    <p>The relationship between EMF, terminal voltage, and internal resistance</p> Signup and view all the answers

    How do you calculate the equivalent resistance in a parallel circuit with two resistors?

    <p>$Req = rac{R_1R_2}{R_1 + R_2}$</p> Signup and view all the answers

    Which statement correctly describes the temperature coefficient of resistance for alloys like Nichrome?

    <p>They have a temperature coefficient of $x=0$</p> Signup and view all the answers

    What does the voltage drop equation, $ΔV = V_2 - V_1$, represent?

    <p>The decrease in voltage across a resistor</p> Signup and view all the answers

    Which geometrical measure is represented by the formula for the body diagonal of a cube?

    <p>Distance across the cube from corner to opposite corner</p> Signup and view all the answers

    What could happen to an insulator's resistance when subjected to a change in temperature?

    <p>Resistance may have a small, yet measurable change</p> Signup and view all the answers

    What is the main purpose of a Wheatstone Bridge?

    <p>Finding unknown resistance</p> Signup and view all the answers

    What is the potential gradient when potential difference is $V$ and length is $L$?

    <p>k = rac{V}{L}</p> Signup and view all the answers

    What happens to the total emf when cells are connected in series?

    <p>It is the sum of individual emfs.</p> Signup and view all the answers

    In a closed circuit, which equation represents the relationship between emf, current, and internal resistance?

    <p>E = I R + I r</p> Signup and view all the answers

    What is the total emf when cells are connected in parallel?

    <p>The total emf is the same as the emf of a single cell.</p> Signup and view all the answers

    How is internal resistance calculated using a potentiometer?

    <p>Using a combination of emf and resistance measurements.</p> Signup and view all the answers

    What is the measure of current in the case of an open circuit?

    <p>I equals zero.</p> Signup and view all the answers

    What is the formula for calculating the magnetic field strength around a long wire?

    <p>$B = rac{ u_0 I}{2 ext{pi} a}$</p> Signup and view all the answers

    When comparing the emf of two cells, what does a positive reading indicate?

    <p>The first cell has a larger emf.</p> Signup and view all the answers

    When resistors are connected in parallel, how is the total current calculated?

    <p>$I = rac{ ext{E}}{R_1 + R_2}$</p> Signup and view all the answers

    What does the internal resistance of a battery affect in a closed circuit?

    <p>It reduces the effective voltage available to the load.</p> Signup and view all the answers

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