Question

1) If the charge on an electron is 1.6 x 10-19 coulomb, how many electrons should pass through a conductor ampere current ?
2) Define electromotive force.
3) State Ohm's law.
4) Define resistance of a conductor.​

Answer 1

1) $\sf{\underline{\underline{\bold{Correct\:Question}}}}$

If the charge on an electron is $\sf{1.6\times 10^{-19}}$ coulomb, how many electrons should pass through a conductor in 1 second to constitute 1 ampere current?

Given:-

• Charge on electron (e) = $\sf{1.6\times 10^{-19}C}$
• Current (I) = 1 A
• Time (t) = 1 s

To find:-

How many electrons should pass through conductor in 1 s to constitute 1 ampere current.

Solution:-

We know,

Q = ne [Where Q = charge of current, n = number of electrons and e = charge of electron]

=> $\sf{n = \dfrac{Q}{e}}$

Therefore, to fine the number of electrons we first need to find the charge of electric current.

Therefore,

Current (I) = 1 A

Time (t) = 1

We know,

$\sf{I = \dfrac{Q}{t}}$

=> $\sf{Q = I\times t}$

= $\sf{Q = 1\times1}$

= $\sf{Q = 1\:C}$

Now,

Q = 1 C

e = $\sf{1.6 \times 10^{-19}}$

To find the number of electrons,

Q = ne

=> $\sf{n = \dfrac{Q}{e}}$

= $\sf{n = \dfrac{1}{1.6\times 10^{-19}}}$

= $\sf{n = 6.25\times 10^{18}}$

Therefore number of electrons which should pass through the conductor in 1 second to constitute 1 ampere of current is $\sf{6.25\times10^{18}}$

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2) Electromotive force:-

Electromotive force is defined as the difference of electric potential which produces electric current.

SI unit of EMF is Volts (V).

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3) Ohm's law:-

Ohm's law states that the potential difference of a conductor is directly proportional to the current flowing in the conductor.

$\sf{V\propto I}$

Formula of Ohm's law is:-

V = IR where R is constant.

R –> Resistance in a conductor

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4) Resistance of a conductor:-

Resistance of a conductor is a property which resists the flow of electrons in a conductor.

Factors on which resistance depend are:-

(i) Area of cross-section:- Resistance is inversely proportional to the area of cross-section of a conductor.

$\sf{R\propto\dfrac{1}{A}}$

(ii) Length of the conductor:- Resistance is directly proportional to length of the conductor.

$\sf{R \propto L}$

(iii) Temperature of the conductor:- Resistance is directly proportional to temperature of the conductor.

(iv) Nature of material:- Resistance is directly proportional to nature of material.

SI unit of Resistance is ohm $\sf{\Omega}$

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Answer 2

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• 1.] 6.25 × 10^18 electrons should pass though a conductor in 1 second to constitute 1 ampere current.

━━━━━━━━━━━━━━━━━━━━━━━━

• 2.] A difference in potential that tends to give rise to an electric current.

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• 3.] The amount of steady current through a large number of materials is directly proportional to the potential difference, or voltage, across the materials.

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• 4.] Resistance is defined as the opposition to the flow of electrical current through a conductor.It's important to point out that conductivity and resistivity (the property that determines final resistance) are inversely proportional.