Unit of Current MCQs

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Unit of Current is Ampere. Ampere is the SI unit of current. It forms one of the fundamental units of physical quantities. Ampere is denoted by A. Electric current is the rate of flow of charge. The value of the charge of an electron e is 1.602 x 176634 ×10-19. Unit of current is very important to know to solve problems related to Current Electricity.

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MCQs on Unit of Current

Ques 1. What is the unit of current?

  1. Ampere
  2. Volt
  3. Ohm
  4. Watt

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Answer: a

Explanation: SI unit of electric current is Ampere. Ampere is the flow of electric charge at the rate of 1 coulomb per second. Ampere is denoted by the symbol A. Electric current is measured by a device called Ammeter.

Ques 2. Electric pressure is also called?

  1. Resistance
  2. Voltage
  3. Wattage
  4. Power

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Answer: b

Explanation: Voltage is defined as the work needed per unit of charge to move a test charge between the two points. It is also called electric potential difference, electric pressure or electric tension is the difference in electric potential between two points.

Ques 3. Materials that offer less resistance and enables free movement of electrons is called?

  1. Conductors
  2. Insulators
  3. Semiconductor
  4. Inductors

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Answer: a

Explanation: Conductors are materials that have free electrons which enables them to conduct electricity. 

Ques 4. Which one is a poor conductor of electricity?

  1. Iron
  2. Silver
  3. Wood
  4. Tungsten

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Answer: c

Explanation: Wood is a non-conductive material and thus acts as an insulator. Most of the metals are very good conductors of electricity.

Ques 5. The property by which a material allows current to pass through it is called?

  1. Resistance
  2. Reactance
  3. Capacitance
  4. Conductance

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Answer: d

Explanation: Conductance is the property of a material to conduct electricity. Conductivity is amount or effective current a material can conduct. It is denoted by σ.

Ques 6. Conductance is the reciprocal of?

  1. Resistance
  2. Reactance
  3. Capacitance
  4. Conductance

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Answer: a

Explanation: Conductance is the property of a material to conduct electricity. On the other hand, resistance is the property of a material to resist the electric current from passing through it.

Ques 7. Resistance varies inversely with?

  1. Length
  2. Cross section
  3. Temperature
  4. Resistivity

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Answer: b

Explanation: Resistance is directly proportional to resistivity and length. It is inversely proportional to cross sectional area of the conductor.

R = \(\frac{pL}{A}\) p = resistivity, L = length, A = cross sectional area

Ques 8. Which instrument is used to detect electric current?

  1. Galvanometer
  2. Wattmeter
  3. Rheostat
  4. Voltmeter

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Answer: a

Explanation: Galvanometer is a device used to measure electric current and intensity. It is indicated by a magnetic needle's movement or that of a coil in a magnetic field. A galvanometer is also used as an ammeter and a voltmeter. 

Ques 9. Calculate the voltage across a 33 ohm resistor carrying 2A current.

  1. 33V
  2. 46V
  3. 66V
  4. 99V

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Answer: c

Explanation: By Ohm’s law,

V = IR

V = 2 x 33

V = 66 volts

Ques 10. Calculate the resistance of a light bulb if its voltage is 5V and carries a current 10A.

  1. 0.2 Ohms
  2. 0.1 Ohms
  3. 0.5 Ohms
  4. 2 Ohms

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Answer: c

Explanation: By Ohm’s law,

V = IR

R = V/I

R = 5/10

R = 0.5 Ohms

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CBSE CLASS XII Related Questions

  • 1.
    Nuclides with the same number of neutrons are called:

      • Isobars
      • Isotones
      • Isotopes
      • Isomers

    • 2.
      The magnetic field in a plane electromagnetic wave travelling in glass (\( n = 1.5 \)) is given by \[ B_y = (2 \times 10^{-7} \text{ T}) \sin(\alpha x + 1.5 \times 10^{11} t) \] where \( x \) is in metres and \( t \) is in seconds. The value of \( \alpha \) is:

        • \( 0.5 \times 10^3 \, \text{m}^{-1} \)
        • \( 6.0 \times 10^2 \, \text{m}^{-1} \)
        • \( 7.5 \times 10^2 \, \text{m}^{-1} \)
        • \( 1.5 \times 10^3 \, \text{m}^{-1} \)

      • 3.
        Assertion : In Young’s double-slit experiment, the fringe width for dark and bright fringes is the same. Reason (R): Fringe width is given by \( \beta = \frac{\lambda D}{d} \), where symbols have their usual meanings.

          • Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
          • Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
          • Assertion (A) is true, but Reason (R) is false.
          • Both Assertion (A) and Reason (R) are false.

        • 4.
          A part of a wire carrying \( 2.0 \, \text{A} \) current and bent at \( 90^\circ \) at two points is placed in a region of uniform magnetic field \( \vec{B} = -0.50 \, \hat{k} \, \text{T} \), as shown in the figure. Calculate the magnitude of the net force acting on the wire.


            • 5.
              In a Young's double-slit experiment, two waves each of intensity I superpose each other and produce an interference pattern. Prove that the resultant intensities at maxima and minima are 4I and zero respectively.


                • 6.
                  Assertion : Photoelectric effect is a spontaneous phenomenon. Reason (R): According to the wave picture of radiation, an electron would take hours/days to absorb sufficient energy to overcome the work function and come out from a metal surface.

                    • Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
                    • Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
                    • Assertion (A) is true, but Reason (R) is false.
                    • Both Assertion (A) and Reason (R) are false.
                  CBSE CLASS XII Previous Year Papers

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