1

What is the principle behind the operation of a transformer?

A

Law of Conservation of Energy

B

Ohm's Law

C

Faraday's Law of Electromagnetic Induction

D

Newton's Law of Universal Gravitation

E

Answer

C, Explanation: Transformers operate based on Faraday's Law of Electromagnetic Induction. According to this law, when the magnetic flux linking a circuit changes, an electromotive force (EMF) is induced in the circuit. In a transformer, alternating current in the primary coil creates a changing magnetic field, which induces a voltage in the secondary coil through electromagnetic induction. This process allows for the transfer of electrical energy from one circuit to another, typically with a change in voltage levels. Choices A, B, and D are unrelated to the principle behind transformer operation.

Instruction

2

What is the primary energy source primarily used to generate electricity in a modern power plant?

A

Hydroelectric energy

B

Wind energy

C

Fossil fuel energy

D

Nuclear energy

E

Answer

C, Explanation: In a modern power plant, fossil fuel energy is primarily used to generate electricity. Fossil fuel energy involves generating energy from the combustion of fossil fuels such as coal, which produces steam that drives turbines, ultimately generating electricity. Options A, B, and D negate the primary energy sources generated.

Instruction

3

Which of the following is a fundamental force responsible for holding the nucleus of an atom together?

A

Gravitational force

B

Electromagnetic force

C

Strong nuclear force

D

Weak nuclear force

E

Answer

C, Explanation: The strong nuclear force is the fundamental force responsible for holding the nucleus of an atom together. This force acts between nucleons (protons and neutrons) and overcomes the electrostatic repulsion between positively charged protons in the nucleus. It is a short-range force but is extremely powerful at close distances within the nucleus.

Instruction

4

Which of the following devices is used to measure electric current in a circuit?

A

Voltmeter

B

Ammeter

C

Ohmmeter

D

Galvanometer

E

Answer

B, Explanation: An ammeter is used to measure electric current in a circuit. It is connected in series with the circuit, and it measures the flow of electric charge (current) passing through it. Voltmeter (Option A) is used to measure voltage, Ohmmeter (Option C) measures resistance, and Galvanometer (Option D) is a sensitive instrument used to detect and measure small electric currents. However, to measure electric current accurately, an ammeter is employed.

Instruction

5

What is the SI unit of electric charge?

A

Volt

B

Ampere

C

Coulomb

D

Ohm

E

Answer

C, Explanation: The SI unit of electric charge is the Coulomb (C). It is named after the French physicist Charles-Augustin de Coulomb, who made significant contributions to the field of electromagnetism.

Instruction

6

Which of the following is NOT a type of mechanical wave?

A

Sound wave

B

Light wave

C

Water wave

D

Seismic wave

E

Answer

B, Explanation: Light waves are electromagnetic waves, not mechanical waves. Mechanical waves require a medium to propagate, while electromagnetic waves can travel through a vacuum. Sound waves (Option A), water waves (Option C), and seismic waves (Option D) are examples of mechanical waves because they propagate through a material medium by the transfer of energy from particle to particle.

Instruction

7

What is the SI unit of frequency?

A

Hertz

B

Newton

C

Joule

D

Pascal

E

Answer

A, Explanation: The SI unit of frequency is the Hertz (Hz). It is defined as one cycle per second. One Hertz equals one cycle per second. Options B, C, and D represent the SI units of force, energy, and pressure, respectively.

Instruction

8

What is the critical mass of a fissile material?

A

The minimum mass required for a nuclear reaction to become self-sustaining

B

The maximum mass at which a nuclear reactor can operate efficiently

C

The amount of mass lost during a nuclear fission reaction

D

The mass of a nucleus at which it becomes unstable and undergoes radioactive decay

E

Answer

A, Explanation: The critical mass of a fissile material refers to the minimum amount of mass needed for a nuclear chain reaction to become self-sustaining. Below this critical mass, the reaction will not produce enough neutrons to continue, while above it, the reaction will generate enough neutrons to sustain itself.

Instruction

9

What is the process by which a solid change directly into a gas without passing through the liquid state called?

A

Condensation

B

Sublimation

C

Evaporation

D

Deposition

E

Answer

B, Explanation: The process by which a solid change directly into a gas without passing through the liquid state is called sublimation. During sublimation, solid particles gain enough energy to break free from their fixed positions and enter the gas phase.

Instruction

10

What is the fundamental principle underlying the operation of a scanning tunneling microscope (STM)?

A

Quantum entanglement

B

Pauli exclusion principle

C

Tunneling effect

D

Photoelectric effect

E

Answer

C, Explanation: The fundamental principle underlying the operation of a scanning tunneling microscope (STM) is the tunneling effect. In STM, a sharp metal tip is brought very close to the surface of a sample, and a small bias voltage is applied between the tip and the sample. Due to the quantum mechanical tunneling effect, electrons can pass through the vacuum gap between the tip and the sample, leading to a measurable tunneling current. This current is highly sensitive to the distance between the tip and the sample surface, allowing for the visualization of atomic-scale features.

Instruction