Physics Short Questions and Answers for Exam Preparation
Posted on Apr 25, 2026 in Physics
SECTION B: SHORT QUESTIONS
Q1. Define the Following with Examples
- Frequency (f): The number of complete waves passing a point per second. Unit: Hertz (Hz). Formula: f = 1/T. Example: 50 cycles per second = 50 Hz.
- Wavelength (λ): The distance between two consecutive crests or troughs. Unit: Metre (m). Formula: v = fλ. Example: Visible light is 400–700 nm.
- Time Period (T): The time taken to complete one full vibration. Unit: Second (s). Formula: T = 1/f. Example: A pendulum swing taking 2 seconds.
- Refraction: The bending of a wave when passing between media of different densities. Example: A pencil appearing bent in water. Formula: n = c/v.
- Interference: The superposition of two waves of the same frequency. Constructive (larger amplitude) or Destructive (smaller/zero amplitude). Example: Colours on a soap bubble.
- Radioisotope: An unstable isotope that emits radiation to become stable. Example: Carbon-14 for dating; Iodine-131 for thyroid treatment.
- Isotopes and Isobars of Hydrogen:
- Isotopes: Same atomic number, different mass. (Protium, Deuterium, Tritium).
- Isobars: Different elements, same mass number. Example: Tritium (₁³H) and Helium-3 (₂³He).
- Current and Its Types: Flow of electric charge (I = Q/t).
- DC: Flows in one direction (e.g., batteries).
- AC: Changes direction periodically (e.g., household supply).
- Resistance (R): Opposition to current flow. Unit: Ohm (Ω). Formula: R = V/I.
- Power of Lens (P): Ability to converge/diverge light. Unit: Diopter (D). Formula: P = 1/f.
- Radioactivity: Spontaneous emission of radiation from an unstable nucleus. Discovered by Henri Becquerel (1896). Types: Alpha, Beta, Gamma.
Q2. Differentiate Between the Following
| Regular Reflection | Irregular (Diffuse) Reflection |
|---|
| Smooth, polished surfaces | Rough, uneven surfaces |
| Parallel reflected rays | Scattered reflected rays |
| Clear image formed | No clear image |
| Alpha (α) Rays | Beta (β) Rays |
|---|
| Helium nuclei (+2 charge) | Fast-moving electrons (-1 charge) |
| Least penetrating | Medium penetrating |
| Electromagnetic Waves | Mechanical Waves |
|---|
| No medium required | Requires material medium |
| Travel in vacuum | Cannot travel in vacuum |
| Concave Lens | Convex Lens |
|---|
| Diverging; negative power | Converging; positive power |
| Virtual, erect image | Real or virtual image |
| Alternating Current (AC) | Direct Current (DC) |
|---|
| Periodic direction change | One-way flow |
| Used in households | Used in electronics |
| Analog Electronics | Digital Electronics |
|---|
| Continuous signals | Binary (0 or 1) signals |
| Noise-prone | Noise-resistant |
Q3. Notes on Physics Concepts
- Characteristics of Sound: Loudness (amplitude), Pitch (frequency), Quality (waveform), and Speed (Solid > Liquid > Gas).
- Laws of Reflection and Refraction: Reflection (∠i = ∠r). Refraction (Snell’s Law: n = sin i / sin r).
- Capacitors: Devices storing charge (C = Q/V). Series (1/C = 1/C₁ + 1/C₂) and Parallel (C = C₁ + C₂) combinations.
- Transformers: Devices using electromagnetic induction to change AC voltage. Step-up (increases voltage) and Step-down (decreases voltage).
Q4. Uses of RADAR, SONAR, and LIDAR
- RADAR: Air traffic control, weather forecasting, speed detection.
- SONAR: Ocean depth measurement, submarine detection, medical imaging.
- LIDAR: Autonomous vehicles, forestry mapping, land surveying.
Q5. Electromagnetic Waves
Characteristics: Transverse nature, no medium required, speed of 3 × 10⁸ m/s, carry energy.
Uses: Radio (broadcasting), Microwaves (ovens), Infrared (remotes), Visible light (vision), X-rays (medical imaging), Gamma rays (radiotherapy).
