Class 10 Science English Medium

Chapter 12: Electricity

Topics: Electric current, unit of current, potential and potential difference, prevailing symbols of useful equipments in electrical circuits, ohm’s law, resistance, dependence of resistance on length and cross-sectional area, resistivity, combination of resistances.

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1. The frequency of alternating current in India is

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2. Resistivity depends on which of the following?

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3. 2 coulomb charge passes through an electrical circuit in 0.5 second. Find the value of electric current in ampere.

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4. The S.I. unit of electric current is:

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5. Three resistances of 10 $\mathit{\Omega}$, 5 $\mathit{\Omega}$ and 2 $\mathit{\Omega}$ respectively are connected in parallel. Net resistance will be.................

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6. The S.I. unit of electric charge is:

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7. The SI unit of resistivity is

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8. In a circuit containing two unequal resistances connected in parallel .....

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9. 1 kWh is the unit of ..............

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10. An electric bulb is rated 220 V and 100W. When it is operated on 110 V, the power consumed will be:

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11. The S.I. unit of Potential Difference is:

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12. SI unit of resistance is.......

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13. The resistance of an electric conductor of depends on -

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14. Resistances of different values are connected in parallel and connected with an electrical source. In each of the resistor -

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15. Which of the following is SI unit of electric charge?

Important Points : Electricity

Clas 10 Science MCQs of this chapter based on the following topic take a brief revision of the cahpter Electirc Current.

Electric Current:

Rate of flow of charge is called current. Its direction is always taken from positive to negative and it is measured in amperes.

Electric Resistance:

Restriction in the flow of charge is called resistance. It depends upon lenght, cross section area, temperature and the material.

Ohm's Law:

When physical states of aconductor are constant then the potential difference produced across the conductor is proportional to the current flowing through it. It is called Ohm's law.

                   V = IR

Where R is a constant and is known as resistance of conductor.

Measurement of Electric Current and Potential Difference:

  • Ammeter measures current in the circuit and is used in series in the circuit.
  • Voltmeter measures the potential difference across the conductor and is placed parallel to it in a circuit.

 

Specific Resistance:

Resistance of a conducting wire of 1 meter length and 1 square meter cross sectional area is called specific resistance of the material of the wire. Its unit is ohm $\Omega m$  i.e. ohm-metre. It does not depend on length or cross-sectional area of the wire but depends on the material of the wire.

Equivalent resistance in series combination

$$ \mathrm{R}=\mathrm{R}_{1}+\mathrm{R}_{2}+\mathrm{R}_{3} \ldots \ldots $$

Equivalent resistance in parallel combination

$$ \frac{1}{\mathrm{R}}=\frac{1}{\mathrm{R}_{1}}+\frac{1}{\mathrm{R}_{2}}+\frac{1}{\mathrm{R}_{3}}+\ldots . . $$

A pure resistor is connected to an electric source. The energy given to the pure resistor by electric source $(\mathrm{W}=\mathrm{VIt})$ fully transforms into heat energy.

Ohm's Law Diagram