⭐ 50 Basic Physics GK Questions for Competitive Exams
(With Answers & Detailed Explanations)
Physics is an important section for all competitive exams like SSC, Railway, Banking, Defence, Police, UPSC, and State-level exams. Below are the 50 most important and repeatedly asked Basic Physics GK Questions with clear answers and explanations.
Top 50 Basic Physics GK Questions with Answers
1. What is Physics?
Answer: The study of matter, energy, and their interactions.
Explanation: Physics explains natural phenomena, motion, force, heat, sound, electricity, etc.
2. Who is known as the Father of Physics?
Answer: Isaac Newton
Explanation: Newton developed the laws of motion, gravitation, and major principles of mechanics.
3. What is the speed of light in a vacuum?
Answer: 3 × 10⁸ m/s
Explanation: It is universal and constant for all observers.
4. What is the SI unit of energy?
Answer: Joule
Explanation: Work and energy both share the same unit.
5. What is the SI unit of force?
Answer: Newton
Explanation: Derived from F = ma (Newton’s Second Law).
6. Who discovered the law of gravitation?
Answer: Isaac Newton
Explanation: Based on the observation of an apple falling.
7. What is the formula of density?
Answer: Density = Mass / Volume
Explanation: Higher mass in the same volume = higher density.
8. Which instrument measures temperature?
Answer: Thermometer
Explanation: Mercury or digital sensors are commonly used.
9. What is the SI unit of power?
Answer: Watt
Explanation: 1 watt = 1 joule per second.
10. What is the SI unit of current?
Answer: Ampere
Explanation: It denotes the flow of electric charge.
11. What is the device used to measure electric current?
Answer: Ammeter
Explanation: Connected in series to measure current.
12. What is the device used to measure voltage?
Answer: Voltmeter
Explanation: Always connected in parallel.
13. What is kinetic energy?
Answer: Energy due to motion.
Explanation: KE = ½ mv².
14. What is potential energy?
Answer: Stored energy due to position.
Explanation: PE = mgh.
15. Who discovered X-rays?
Answer: Wilhelm Röntgen
Explanation: Received the first Nobel Prize in Physics.
16. Sound travels fastest in which medium?
Answer: Solids
Explanation: Molecules are closest in solids.
17. Which quantity is measured in decibels?
Answer: Sound intensity
Explanation: Measures loudness.
18. What is the SI unit of frequency?
Answer: Hertz (Hz)
Explanation: 1 Hz = 1 cycle per second.
19. Who invented the telescope?
Answer: Galileo Galilei
Explanation: Improved early versions for astronomy.
20. What is refraction?
Answer: Bending of light when it passes from one medium to another.
Explanation: Due to change in speed of light.
21. What is reflection?
Answer: Bouncing back of light from a surface.
Explanation: Mirrors work on reflection.
22. What type of mirror is used in rear-view mirrors?
Answer: Convex mirror
Explanation: Gives a wider field of view.
23. What is the SI unit of pressure?
Answer: Pascal
Explanation: 1 Pa = 1 Newton per square meter.
24. What instrument measures atmospheric pressure?
Answer: Barometer
Explanation: Invented by Torricelli.
25. What is buoyancy?
Answer: Upward force exerted by a fluid on an object.
Explanation: Responsible for floating objects.
26. Who invented the electric bulb?
Answer: Thomas Alva Edison
Explanation: Improved the carbon filament bulb.
27. What is the speed of sound in air?
Answer: 343 m/s
Explanation: At room temperature (25°C).
28. What is Ohm’s Law?
Answer: V = IR
Explanation: Voltage = Current × Resistance.
29. What is the unit of electric resistance?
Answer: Ohm
Explanation: Represented by Ω.
30. What is the full form of LASER?
Answer: Light Amplification by Stimulated Emission of Radiation.
31. What is the full form of RADAR?
Answer: Radio Detection and Ranging.
32. What kind of energy is stored in a stretched spring?
Answer: Elastic potential energy.
33. What is inertia?
Answer: The tendency of an object to resist change in motion.
Explanation: Newton’s First Law.
34. Which metal is used in electrical wiring?
Answer: Copper
Explanation: High conductivity.
35. Which gas is used in CFL bulbs?
Answer: Argon
Explanation: Helps glow mercury vapor.
36. What is a conductor?
Answer: Material that allows electric current to pass.
Example: Copper, Aluminium.
37. What is an insulator?
Answer: Material that resists electric flow.
Example: Rubber, Wood.
38. What is work?
Answer: Force × displacement.
Explanation: Measured in joules.
39. What is the unit of power of lenses?
Answer: Dioptre
Explanation: D = 1/f (f in meters).
40. Which color has the longest wavelength?
Answer: Red
Explanation: Least refracted.
41. Which color has the shortest wavelength?
Answer: Violet
Explanation: Most refracted.
42. What is velocity?
Answer: Speed with direction.
Explanation: Vector quantity.
43. What is acceleration?
Answer: Rate of change of velocity.
Unit: m/s²
44. What is momentum?
Answer: Mass × velocity
Explanation: p = mv.
45. What is the instrument to measure humidity?
Answer: Hygrometer
Explanation: Used in weather stations.
46. Which radiation has the highest energy?
Answer: Gamma rays
Explanation: Highest frequency.
47. What is the weight?
Answer: Force of gravity on an object.
Formula: W = mg
48. What is the universal gravitational constant (G)?
Answer: 6.67 × 10⁻¹¹ Nm²/kg²
Explanation: Newton’s law constant.
49. Which lens is used in microscopes?
Answer: Convex lens
Explanation: Magnifies objects.
50. What is the unit of heat?
Answer: Joule (SI unit)
Explanation: Calories are also used in some systems.
⭐ Conclusion
These 50 Basic Physics GK Questions and Answers are extremely important for all competitive exams. You can save or download them for quick revision.