Electricity and Magnetism

The word 'electricity' is derived from the Greek word 'elektron', which means:

A. Amber

B. Magnet

C. Friction

D. Electron

Correct Answer: A

Explanation/Solution: William Gilbert coined the term electricity from the Greek word 'elektron', meaning amber.

Who was the English physician who coined the term 'electricus' (like amber)?

A. Michael Faraday

B. William Gilbert

C. Charles Coulomb

D. Benjamin Franklin

Correct Answer: B

Explanation/Solution: William Gilbert coined 'electricus' in 1600 in his treatise De Magnete.

What type of electricity is characterized by electric charges at rest?

A. Dynamic electricity

B. Static electricity

C. Alternating current

D. Transient electricity

Correct Answer: B

Explanation/Solution: Static electricity refers to electric charges at rest.

The flow of electric charges continuously in only one direction is known as:

A. Alternating Current (AC)

B. Direct Current (DC)

C. Eddy Current

D. Displacement Current

Correct Answer: B

Explanation/Solution: Direct Current (DC) is the unidirectional flow of electric charge.

What is the rest mass of an electron in kilograms?

A. 1.6726 x 10^-27 kg

B. 9.1094 x 10^-31 kg

C. 1.6749 x 10^-27 kg

D. 9.1094 x 10^-28 kg

Correct Answer: B

Explanation/Solution: The mass of an electron is approximately 9.1094 x 10^-31 kg.

The mass of a proton is approximately how many times greater than the mass of an electron?

A. 1836 times

B. 2000 times

C. 1000 times

D. 540 times

Correct Answer: A

Explanation/Solution: A proton is approximately 1836 times heavier than an electron.

Who is credited with the discovery of the electron in 1897?

A. Ernest Rutherford

B. James Chadwick

C. Joseph John Thomson

D. Niels Bohr

Correct Answer: C

Explanation/Solution: J.J. Thomson discovered the electron using cathode ray tube experiments.

The neutron was discovered in 1932 by which physicist?

A. Ernest Rutherford

B. James Chadwick

C. John Dalton

D. Max Planck

Correct Answer: B

Explanation/Solution: James Chadwick discovered the neutron.

The discovery of the atomic nucleus and proton is credited to:

A. Ernest Rutherford

B. J.J. Thomson

C. Neils Bohr

D. Robert Millikan

Correct Answer: A

Explanation/Solution: Ernest Rutherford discovered the nucleus/proton via the gold foil alpha scattering experiment.

What atomic model depicts electrons orbiting the nucleus in planetary circular paths at discrete energy levels?

A. Thomson Plum Pudding Model

B. Dalton Solid Sphere Model

C. Bohr Planetary Model

D. Quantum Mechanical Model

Correct Answer: C

Explanation/Solution: The Bohr Model (Planetary Model) depicts electrons in discrete concentric circular shells.

According to Bohr's model, the maximum number of electrons that can occupy a shell with principal quantum number 'n' is given by:

A. 2n

B. n^2

C. 2n^2

D. 4n^2

Correct Answer: C

Explanation/Solution: The formula Ne = 2n^2 determines the maximum capacity of an electron shell.

Electrons that occupy the outermost energy shell of an atom are called:

A. Core electrons

B. Valence electrons

C. Free electrons

D. Bound electrons

Correct Answer: B

Explanation/Solution: Electrons in the outermost shell are called valence electrons.

The number of protons found in the nucleus of an atom defines its:

A. Mass number (A)

B. Atomic number (Z)

C. Valency

D. Isotopic index

Correct Answer: B

Explanation/Solution: Atomic number (Z) represents the total number of protons in an atom's nucleus.

Atoms that possess the same number of protons but different numbers of neutrons are termed:

A. Isotones

B. Isobars

C. Isotopes

D. Isomers

Correct Answer: C

Explanation/Solution: Isotopes have equal number of protons (same atomic number) but different neutrons (different mass number).

Nuclides that have the same number of neutrons but different atomic numbers are known as:

A. Isotopes

B. Isotones

C. Isobars

D. Allotropes

Correct Answer: B

Explanation/Solution: Isotones are nuclides with the same number of neutrons (N) but different proton counts (Z).

Atoms having the same mass number (A) but different atomic numbers (Z) are called:

A. Isotopes

B. Isotones

C. Isobars

D. Isomers

Correct Answer: C

Explanation/Solution: Isobars have identical mass numbers (sum of protons and neutrons) but different atomic numbers.

What is an electrically unbalanced atom that has gained or lost one or more electrons?

A. Molecule

B. Ion

C. Isotope

D. Positron

Correct Answer: B

Explanation/Solution: An atom with a net electric charge due to the loss or gain of electrons is an ion.

A positively charged ion formed when a neutral atom loses valence electrons is a/an:

A. Anion

B. Cation

C. Positron

D. Isotone

Correct Answer: B

Explanation/Solution: A cation is a positively charged ion produced by losing electrons.

The amount of energy required to remove an electron from the valence shell of an isolated neutral atom is called:

A. Binding energy

B. Ionization energy

C. Fermi energy

D. Work function

Correct Answer: B

Explanation/Solution: Ionization energy is the energy required to dislodge a valence electron from an atom.

How many valence electrons do good electrical conductors (such as Copper, Silver, and Gold) typically possess?

A. Exactly 4

B. Fewer than 4

C. Greater than 4

D. Exactly 8

Correct Answer: B

Explanation/Solution: Conductors have fewer than 4 valence electrons (typically 1, 2, or 3).

In an energy band diagram, what is the region separating the valence band and the conduction band where no electron states exist?

A. Fermi level

B. Forbidden energy gap (Eg)

C. Depletion region

D. Conduction gap

Correct Answer: B

Explanation/Solution: The forbidden band (energy gap Eg) is the energy interval between the valence and conduction bands.

What is the typical energy gap (Eg) of an electrical insulator at room temperature?

A. Eg = 0 eV

B. Eg < 1 eV

C. Eg > 5 eV

D. Eg = 1.1 eV

Correct Answer: C

Explanation/Solution: Insulators typically have large forbidden band gaps greater than 5 eV.

What is the energy bandgap (Eg) of Silicon (Si) at room temperature (300 K)?

A. 0.67 eV

B. 1.1 eV

C. 1.43 eV

D. 0.0 eV

Correct Answer: B

Explanation/Solution: Silicon has a bandgap of approximately 1.1 eV at room temperature (300 K).

What is the energy bandgap (Eg) of Germanium (Ge) at room temperature?

A. 0.67 eV

B. 1.1 eV

C. 1.43 eV

D. 3.2 eV

Correct Answer: A

Explanation/Solution: Germanium has a room-temperature energy bandgap of approximately 0.67 eV.

In a conductor, the valence band and conduction band:

A. Are separated by a large forbidden gap

B. Overlap (Eg = 0 eV)

C. Are non-existent

D. Have a gap of 1.43 eV

Correct Answer: B

Explanation/Solution: In electrical conductors, the conduction band overlaps with the valence band (Eg ≈ 0 eV).

One Coulomb of electric charge is equivalent to the charge of how many electrons?

A. 1.602 x 10^-19 electrons

B. 6.25 x 10^18 electrons

C. 6.25 x 10^15 electrons

D. 3.00 x 10^8 electrons

Correct Answer: B

Explanation/Solution: 1 C / (1.602 x 10^-19 C/e) = 6.25 x 10^18 electrons.

According to Coulomb's Law of Electrostatics, the electrostatic force between two point charges is:

A. Directly proportional to the distance between them

B. Inversely proportional to the product of the charges

C. Inversely proportional to the square of the distance between them

D. Directly proportional to the permittivity of the medium

Correct Answer: C

Explanation/Solution: Coulomb's Law states F = k (q1 q2) / r^2, so F is inversely proportional to r^2.

The permittivity of free space (vacuum), denoted as ε₀, has an approximate value of:

A. 8.854 x 10^-12 F/m

B. 8.99 x 10^9 F/m

C. 4π x 10^-7 H/m

D. 1.257 x 10^-6 H/m

Correct Answer: A

Explanation/Solution: ε₀ = 8.854 x 10^-12 Farads per meter (F/m).

What is the SI unit of Electric Field Intensity (E)?

A. Coulomb per square meter (C/m^2)

B. Newton per Coulomb (N/C) or Volt per meter (V/m)

C. Joule per Coulomb (J/C)

D. Tesla (T)

Correct Answer: B

Explanation/Solution: Electric field intensity is measured in Newtons per Coulomb (N/C) or Volts per meter (V/m).

Electric field lines always originate from:

A. Negative charges and terminate at positive charges

B. Positive charges and terminate at negative charges

C. Infinity and terminate at neutral atoms

D. Closed loops with no start or end

Correct Answer: B

Explanation/Solution: By convention, electrostatic lines of force emanate from positive charges and end on negative charges.