CSS - PMS - CCE - PCS - General Science
Waves & Sound - Frequency
Human hearing is commonly approximated as spanning which frequency range?
A. 20 kHz to 200 kHz only
B. 1 MHz to 10 MHz
C. 1 Hz to 10 Hz
D. About 20 Hz to 20 kHz
Correct Answer: D
Young healthy humans typically hear roughly 20 Hz–20,000 Hz.
CSS - PMS - CCE - PCS - General Science
Waves & Sound - Frequency
If wave speed is constant and frequency increases, wavelength does what?
A. Stays always identical
B. Becomes zero instantly
C. Increases
D. Decreases
Correct Answer: D
Since λ = v/f, higher frequency means shorter wavelength.
CSS - PMS - CCE - PCS - General Science
Waves & Sound - Frequency
Which relation connects wave speed v, frequency f and wavelength λ?
A. v = λ/f
B. v = fλ
C. v = f+λ
D. v = f/λ
Correct Answer: B
Wave speed equals frequency times wavelength.
CSS - PMS - CCE - PCS - General Science
Waves & Sound - Frequency
What is the SI unit of frequency?
A. Second
B. Meter
C. Decibel
D. Hertz
Correct Answer: D
One hertz means one cycle per second.
CSS - PMS - CCE - PCS - General Science
Waves & Sound - Frequency
What is frequency?
A. Energy per unit mass
B. Distance traveled per cycle
C. Number of cycles or oscillations per unit time
D. Amplitude only
Correct Answer: C
Frequency measures how often a periodic event repeats.
CSS - PMS - CCE - PCS - General Science
Modern Physics - Radioactivity
Which type of radiation is generally most penetrating among alpha, beta and gamma?
A. Alpha
B. Beta
C. Gamma
D. They are always identical
Correct Answer: C
Gamma rays typically have greater penetration, though shielding depends on energy and material.
CSS - PMS - CCE - PCS - General Science
Modern Physics - Radioactivity
What is half-life?
A. Time required for half the radioactive nuclei in a sample to decay
B. Time for all nuclei to decay exactly
C. Time for temperature to halve
D. Time for mass to double
Correct Answer: A
Half-life is a statistical decay timescale characteristic of a radionuclide.
CSS - PMS - CCE - PCS - General Science
Modern Physics - Radioactivity
Which radiation is high-energy electromagnetic radiation from the nucleus?
A. Beta particles only
B. Gamma radiation
C. Sound
D. Alpha radiation
Correct Answer: B
Gamma rays are photons emitted in nuclear transitions.
CSS - PMS - CCE - PCS - General Science
Modern Physics - Radioactivity
Which radiation commonly consists of high-energy electrons or positrons?
A. Neutrons only
B. Alpha radiation
C. Beta radiation
D. Gamma radiation
Correct Answer: C
Beta decay emits electrons or positrons along with neutrinos or antineutrinos.
CSS - PMS - CCE - PCS - General Science
Modern Physics - Radioactivity
Which radiation consists of helium nuclei?
A. Alpha radiation
B. X-rays only
C. Beta radiation
D. Gamma radiation
Correct Answer: A
Alpha particles contain two protons and two neutrons.
CSS - PMS - CCE - PCS - General Science
Modern Physics - Radioactivity
What is radioactivity?
A. Electron flow in a wire
B. Chemical burning only
C. Light reflection
D. Spontaneous decay of unstable atomic nuclei with emission of radiation
Correct Answer: D
Unstable nuclei can transform spontaneously and emit particles or photons.
CSS - PMS - CCE - PCS - General Science
Modern Physics - Lasers
Which is a common laser application?
A. Measuring mass with a balance only
B. Barcode scanning
C. Boiling water only
D. Producing gravity
Correct Answer: B
Lasers are widely used in scanning, communications, medicine, manufacturing and research.
CSS - PMS - CCE - PCS - General Science
Modern Physics - Lasers
Which component reflects light back and forth through the gain medium in many lasers?
A. Thermometer
B. Optical cavity with mirrors
C. Ammeter
D. Battery only
Correct Answer: B
The resonator provides feedback and selects optical modes.
CSS - PMS - CCE - PCS - General Science
Modern Physics - Lasers
What is population inversion?
A. No atoms present
B. Equal numbers of photons and electrons only
C. All atoms in the ground state
D. More particles in an excited state than in a lower relevant state
Correct Answer: D
Population inversion is required for net optical amplification.
CSS - PMS - CCE - PCS - General Science
Modern Physics - Lasers
What is stimulated emission?
A. A photon splits into protons
B. An incoming photon triggers an excited atom to emit a matching photon
C. A mirror generates matter
D. An atom absorbs all light permanently
Correct Answer: B
Stimulated emission produces photons matching the stimulating photon in key properties.
CSS - PMS - CCE - PCS - General Science
Modern Physics - Lasers
What is a key property of laser light?
A. Always many unrelated wavelengths
B. No directionality
C. High coherence
D. Always low intensity
Correct Answer: C
Laser light has a high degree of temporal and spatial coherence.
CSS - PMS - CCE - PCS - General Science
Modern Physics - Lasers
What does LASER stand for?
A. Light Absorption by Simple Energy Reflection
B. Linear Amplification of Sound Energy Radiation
C. Light Addition by Solar Emission Rays
D. Light Amplification by Stimulated Emission of Radiation
Correct Answer: D
A laser uses stimulated emission to amplify coherent light.
CSS - PMS - CCE - PCS - General Science
Modern Physics - Atom
What determines the chemical element to which an atom belongs?
A. Number of protons
B. Number of neutrons only
C. Number of electron shells only
D. Atomic mass alone
Correct Answer: A
Atomic number, equal to proton count, defines the element.
CSS - PMS - CCE - PCS - General Science
Modern Physics - Atom
What is an ion?
A. An atom or molecule with a net electric charge
B. A photon
C. A molecule with no electrons or protons ever
D. A neutral neutron only
Correct Answer: A
Ions form when electrons are gained or lost.
CSS - PMS - CCE - PCS - General Science
Modern Physics - Atom
What experiment led Rutherford to propose a small dense nucleus?
A. Michelson-Morley experiment
B. Gold-foil scattering experiment
C. Millikan oil-drop experiment
D. Young's double-slit experiment
Correct Answer: B
Large-angle alpha scattering showed that positive charge and mass are concentrated in a tiny nucleus.