Introduction to Electricity Concepts
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Questions and Answers

What is the S.I. unit of electric charge?

  • Ampere
  • Coulomb (correct)
  • Volt
  • Ohm

Which of the following substances is considered an electrical insulator?

  • Rubber (correct)
  • Copper
  • Sea water
  • Steel

If 3 Coulombs of charge flows through a conductor in 3 seconds, what is the current?

  • 9 Amperes
  • 1 Ampere (correct)
  • 3 Amperes
  • 0.5 Amperes

What does the term electric current refer to?

<p>Rate of flow of electric charge (C)</p> Signup and view all the answers

How is electric potential defined?

<p>Work done in bringing a unit positive charge from infinity (B)</p> Signup and view all the answers

Which of the following statements about conductors is true?

<p>They offer comparatively less opposition to current flow (C)</p> Signup and view all the answers

What happens to charges of the same type when they are brought together?

<p>They repel each other (C)</p> Signup and view all the answers

What is considered one ampere of electric current?

<p>One Coulomb of charge flowing in one second (C)</p> Signup and view all the answers

What is the S.I. unit of resistance?

<p>Ohm (C)</p> Signup and view all the answers

Which of the following factors does NOT affect the resistance of a conductor?

<p>Color of the conductor (C)</p> Signup and view all the answers

According to Ohm's Law, what happens to the current if the voltage is doubled while keeping resistance constant?

<p>Current doubles (C)</p> Signup and view all the answers

What does a rheostat primarily regulate in an electrical circuit?

<p>Current (D)</p> Signup and view all the answers

What is the relationship between resistivity and temperature for materials?

<p>Resistivity increases with temperature (A)</p> Signup and view all the answers

Which of the following correctly describes 1 Ohm?

<p>1 Volt for 1 Ampere (C)</p> Signup and view all the answers

In a V-I graph according to Ohm's Law, what does the slope of the line represent?

<p>Resistance (D)</p> Signup and view all the answers

Which symbol represents a closed plug key or switch in a circuit diagram?

<p>(.) (C)</p> Signup and view all the answers

What happens to the electrical resistance of copper wire as its temperature increases?

<p>It increases. (D)</p> Signup and view all the answers

Which factor will decrease the resistance of a wire with fixed length?

<p>Increasing the diameter of the wire. (B)</p> Signup and view all the answers

If the length of a wire is doubled while keeping its resistance constant, what happens to its cross-sectional area?

<p>It is doubled. (D)</p> Signup and view all the answers

What is the calculated resistance of an unknown resistor given a current of 100 mA and a voltage of 4V?

<p>40 Ω (D)</p> Signup and view all the answers

Which property determines the electrical resistivity of a metallic wire?

<p>The nature of the material. (C)</p> Signup and view all the answers

In terms of resistivity, if two wires are made from the same material but one wire is twice as long as the other, how do their resistivities compare?

<p>They are equal. (D)</p> Signup and view all the answers

What is the effect on resistance if the diameter of a wire is decreased while keeping its length constant?

<p>The resistance increases. (A)</p> Signup and view all the answers

When comparing electrical conductivity between copper and aluminum, which statement is true?

<p>Copper has lower resistivity than aluminum. (B)</p> Signup and view all the answers

What is the S.I. unit of potential difference?

<p>Volt (A)</p> Signup and view all the answers

Which device is used to measure the potential difference in a circuit?

<p>Voltmeter (C)</p> Signup and view all the answers

What is the correct formula for voltage?

<p>V = Work done(W)/Charge(Q) (A)</p> Signup and view all the answers

In which direction does conventional current flow in a circuit?

<p>From positive to negative terminal (B)</p> Signup and view all the answers

What converts chemical energy into electrical energy?

<p>Electrochemical cell (D)</p> Signup and view all the answers

What is drift velocity?

<p>The average velocity of electrons in a conductor under an electric field (B)</p> Signup and view all the answers

Which of these components is always connected in series in a circuit?

<p>Ammeter (C)</p> Signup and view all the answers

What is the function of a galvanometer?

<p>To detect current in a circuit (B)</p> Signup and view all the answers

Flashcards

Potential Difference

Difference in electric potential between two points; measured in volts.

Electric Circuit

Closed path for electric current flow.

Conventional Current

Direction of positive charge flow (opposite electron flow).

Electrochemical Cell

Device converting chemical energy to electrical.

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Voltmeter

Measures potential difference (voltage) across a component.

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Ammeter

Measures electric current.

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Drift Velocity

Average speed of electrons in a conductor due to applied electric field.

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Galvanometer

Device detecting electric current.

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Electric Current

The rate of flow of electric charge through a conductor.

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Electric Charge

A fundamental property of matter with positive or negative electrical properties.

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Conductor

A material allowing current to flow easily.

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Insulator

A material that resists the flow of electric current.

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Electric Potential

Work done to move a unit positive charge from infinity to a point.

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Valence Electron

Free electrons in atoms of metals that can conduct electricity.

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Ohm's Law

The current through a conductor is directly proportional to the voltage across it, provided external conditions remain constant.

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Resistance (R)

The property of a conductor that opposes the flow of electric current.

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1 Ohm

The resistance when a 1-volt potential difference generates a 1-ampere current.

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Rheostat

A variable resistor used to control current without affecting voltage.

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Resistivity (ρ)

The resistance of a wire with a unit length and cross-sectional area.

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Electric Cell Symbol

A symbol representing a single battery or power source in a circuit diagram.

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Switch (closed)

Symbol representing a switch that allows current to flow.

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Variable Resistor

A device that changes the amount of a resistance in a circuit, by sliding a contact.

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Alloy Resistance

Alloys are materials that resist oxidation (burning) at high temperatures, making them suitable for use in electrical heating devices.

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Low Resistivity Wires

Copper and aluminum are used for electrical transmission lines because they have low electrical resistance, allowing for efficient electricity flow.

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Heat & Resistance

As the temperature of a copper wire increases, its electrical resistance also increases.

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Wire Resistance & Diameter

The resistance of a wire is inversely proportional to its cross-sectional area (diameter). A thicker wire has lower resistance.

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Resistance & Length

The resistance of a conductor is directly proportional to its length. A longer wire has higher resistance.

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Resistance Formula

The resistance (R) of a conductor is calculated by R = (ρ * L) / A, where ρ (rho) is resistivity, L is length, and A is cross-sectional area.

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Resistivity & Material

Electrical resistivity is a property of the material itself, influencing how much resistance it offers to current flow.

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Ohm's Law & Resistance

Ohm's Law states the relationship between voltage (V), current (I), and resistance (R): V = I * R. Resistance is a factor in determining current flow.

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Study Notes

Introduction to Electricity

  • An atom has a positively charged nucleus and negatively charged electrons revolving around it
  • Valence electrons in metals are free to move within the conductor and constitute an electric current

Charge

  • In physics, charge (electric charge) is a fundamental property of matter that describes the presence of positive or negative electrical properties in particles
  • Charge is a fundamental particle of matter
  • Charge can be positive or negative
  • The SI unit of charge is Coulomb (C)
  • Like charges repel and unlike charges attract

Charge Calculation

  • Q = n × e
    • Q = total charge
    • n = number of electrons
    • e = charge on one electron (1.6 × 10⁻¹⁹ C)

Static and Current Electricity

  • Static electricity deals with electric charges at rest
  • Current electricity deals with electric charges in motion

Electric Current

  • The electric current is defined as the rate of flow of electric charge through any cross section of a conductor
  • Electric current (I) = Charge (Q) / Time (t)
  • The SI unit of current is Ampere (A)
  • 1 ampere = 1 coulomb / 1 second

Resistance (R)

  • Resistance is the property of a conductor to resist the flow of charges through it
  • The SI unit of resistance is Ohm (Ω)
  • 1 Ohm = 1 Volt / 1 Ampere
  • Resistance of a uniform metallic conductor is:
  • Directly proportional to the length of the conductor
  • Inversely proportional to the cross-sectional area
  • Directly proportional to the temperature
  • Depends on nature of material

Resistivity (ρ)

  • Resistivity is the resistance offered by a wire of unit length and unit cross-sectional area
  • Its SI unit is Ohm-metre (Ωm)

Factors Affecting Resistance

  • The resistance of a wire is influenced by its length, cross-sectional area, temperature, and material

Rheostat

  • A rheostat is a variable resistor used to regulate current without changing the voltage source

Components in Electrical Circuits

  • List of components and their symbols

Ohm's Law

  • The current through a conductor between two points is directly proportional to the voltage across the two points, provided external conditions remain constant
  • Mathematical expression: V = IR (where R = Resistance)

V-I Graph

  • The graph between voltage (V) and current (I) is a straight line. The slope of the line is equal to the resistance (R).

Electrochemical Cell (Voltaic Cell)

  • A device that converts chemical energy into electrical energy

Electrical Measuring Instruments

  • Galvanometer: detects current in a circuit
  • Ammeter: measures current in a circuit, low resistance, connected in series
  • Voltmeter: measures potential difference, high resistance, connected in parallel

Drift Velocity

  • The average velocity that an electron attains inside a metallic conductor due to the application of an electric field due to the potential difference

Conventional Current Direction

  • The direction of conventional current is opposite to the direction of the negatively charged electrons.

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Related Documents

L1 - Electricity PDF

Description

Test your knowledge on the fundamentals of electricity, including charge, electric current, and the behavior of electrons. This quiz covers key definitions, calculations, and the distinction between static and current electricity. Enhance your understanding of how electricity works in both theoretical and practical contexts.

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