Potential Difference and Resistance

•    Electric potential is basically an electric pressure. Electric charges flow only when there is an electric pressure difference called potential difference. Conceptually, electric potential is defined as the work done in moving a test charge from a reference point to a specific point which is stored in the form of electrical potential energy. Electric potential may also be defined as the electrical potential energy per unit charge.  
The SI unit of electric potential is volt (V) and is measured using a voltmeter. Potential difference between two points is said to be one volt if one joule of work is done to move one coulomb of charge from one point to the other.
•    The potential difference results in the flow of electric current in the circuit. But every conductor tends to resist the flow of electric current. Electrical resistance is the property of a conductor due to which it resists the flow of electric current when connected in an electrical circuit.

                                                   

•    Conductors offer resistance due to the presence of positive ions which collide with the flowing electrons reducing their rate of flow. Resistance is a scalar quantity and its SI unit is ohm

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  • Q1

    A unit electric charge is moved from a point A to another point B. The work done in this process is called

    Marks:1
    Answer:

    the potential difference between A and B

    Explanation:

    The potential difference between two points in an electric field is defined as the amount of work done in moving a unit positive charge from one point to another point. i.e.

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  • Q2

    Difference of electric pressure is called

    Marks:1
    Answer:

    Potential difference

    Explanation:

    Difference of electric pressure is called potential difference which is responsible for flow of current in the circuit.

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  • Q3

    The work done in moving a charge of 6 C across two points having potential difference 20 V is

    Marks:1
    Answer:

    120 J.

    Explanation:

    Since, potential difference = work done / charge. Therefore, work done = 20 V × 6 C = 120 J.

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  • Q4

    One volt is equal to

    Marks:1
    Answer:

    1 joule/1 coulomb.

    Explanation:
    One volt is the potential difference between two points of a current carrying conductor when one joule of work is done in moving a charge of one coulomb from one point to another.
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  • Q5

    The work done in moving a charge of 2 C across two points having potential difference 20 V is

    Marks:1
    Answer:

    40 J

    Explanation:

    Potential difference = work done / charge

    Work done = 20 V × 2 C = 40 J

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