Electricity Flashcards

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1
Q

What is a switch?

A

A switch makes a conducting link between the cell and the bulb.

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2
Q

How is electric current expressed?

A

Electric current is expressed by the amount of charge flowing through a particular area in unit time.

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3
Q

Why is the direction of positive charges taken as the direction of current?

A

In circuits using electric wires, electrons constitute the
flow of charges. However, electrons were not known at the time when the phenomena of electricity was first discovered. So, electric current was considered to be the flow of positive charges and the direction of the flow of positive charges was taken to be the direction of current. Conventionally, in an electric circuit the direction of the electric current is taken as opposite to the direction of the flow of electrons, which are negative charges.

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4
Q

What is an electric circuit?

A

A continuous and closed path of an electric current is called an electric current.

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5
Q

Coulomb?

A

Coulomb which is equivalent to the charge contained in nearly 6x10 to the power 18 electrons.

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6
Q

An Electron charge?

A

An Electron possess a negative charge of 1.6x10 to the power -19 Coulomb.

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7
Q

One Ampere?

A

One Ampere is constituted by the flow of one Coulomb of charge per second.

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8
Q

Milliampere and microampere

A

Small quantities of current are expressed in milliampere( 1mA = 1/1000 Ampere or 1mA = 10 to the power -3 Ampere) and microampere( 1 microampere = 10 to the power -6 Ampere).

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9
Q

Ammeter? Why should an Ammeter have very low resistance?

A

Device used to measure current, always connected in series. Since the entire current passes through the ammeter, therefore, an ammeter should have very low resistance so that it may not change the value of the current flowing in the circuit.

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10
Q

How does the electric current flow?

A

The electric current flows from the positive terminal of the cell to the negative terminal of the cell through the bulb and the ammeter.

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11
Q

What is electric potential difference?

A

Potential difference between two points in an electric circuit carrying some current is defined as the work done to move a unit charge from one point to the other.

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12
Q

What is potential difference?

A

In a conducting metallic wire, gravity has no role in the movement of charges. Electrons move only when there is a difference of electric pressure called the potential difference.

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13
Q

Current is ———————– to resistance?

A

Inversely Proportional

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14
Q

A component used to regulate current without changing the voltage source is called ?

A

Variable Resistance

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15
Q

In an electric circuit, a device called ——————– is often used to change the resistance in a circuit.

A

Rheostat

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16
Q

How is the motion of the electrons through a conductor is retarded by its resistance?

A

Motion of electrons in an electric circuit constitutes an electric current. The electrons, however are not completely free to move within a conductor. They are restrained by the attraction of the atoms among which they move. Thus motion of electrons through a conductor is retarded by its resistance.

17
Q

A component of a given size that offers a low resistance is a ?

A

Good conductor.

18
Q

A conductor having some appreciable resistance is called a —————————- . A component of identical size that offers a higher resistance is a ———————- .
An —————- of the same size offers even higher resistance.

A

Resistance
Poor Conductor
Insulator