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.
    A tank is filled with a liquid to a height of \( 12.5 \, \text{m} \). The apparent depth of a needle lying at the bottom of the tank is measured to be \( 9.0 \, \text{m} \). Calculate the speed of light in the liquid.


      • 2.
        A long solenoid of length \( L \) and radius \( r_1 \) having \( N_1 \) turns is surrounded symmetrically by a coil of radius \( r_2 \, (r_2>r_1) \) having \( N_2 \) turns (\( N_2 \ll N_1 \)) around its mid-point. Derive an expression for the mutual inductance of solenoid and coil. Is \( M_{12} = M_{21} \) valid in this case?


          • 3.
            Two small identical metallic balls having charges \( q \) and \( -2q \) are kept far at a separation \( r \). They are brought in contact and then separated at distance \( \frac{r}{2} \). Compared to the initial force \( F \), they will now:

              • attract with a force \( \frac{F}{2} \)
              • repel with a force \( \frac{F}{2} \)
              • repel with a force \( F \)
              • attract with a force \( F \)

            • 4.
              Draw the number of scattered particles versus the scattering angle graph for scattering of alpha particles by a thin foil. Write two important conclusions that can be drawn from this plot.


                • 5.
                  What is displacement current (\( i_d \))? Considering the case of charging of a capacitor, show that \( i_d = \varepsilon_0 \frac{d\Phi_E}{dt} \). What is the value of \( i_d \) for a conductor across which a constant voltage is applied?


                    • 6.
                      Write the expression for the magnetic field due to a current element in vector form. Consider a 1 cm segment of a wire, centered at the origin, carrying a current of 10 A in positive x-direction. Calculate the magnetic field \( \mathbf{B} \) at a point \( (1 \, \text{m}, 1 \, \text{m}, 0) \).

                        CBSE CLASS XII Previous Year Papers

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