Unit 1 of Physics often introduces the foundational concepts of the physical world and measurement. Whether you’re preparing for an exam or just brushing up on the basics, MCQs can be a great way to test your knowledge. In this blog post, we discuss 50 carefully selected MCQs on these topics, along with answers and explanations. Let’s get started!
1. Which of the following is not a branch of Physics?
A) Mechanics
B) Thermodynamics
C) Biology
D) Optics
Answer: C) Biology
Explanation: Physics is concerned with the fundamental principles governing matter, energy, and their interactions. Biology is a branch of science focused on living organisms, not a direct branch of Physics.
2. The basic unit of length in the SI system is?
A) Meter
B) Kilometer
C) Centimeter
D) Foot
Answer: A) Meter
Explanation: The International System of Units (SI) defines the meter as the base unit of length. It is the standard measurement unit for length in physics.
3. What is the SI unit of time?
A) Hour
B) Second
C) Minute
D) Day
Answer: B) Second
Explanation: The second is the SI unit for time and is defined as the duration of 9,192,631,770 periods of the radiation corresponding to the transition between two hyperfine levels of the ground state of the cesium-133 atom.
4. Which of the following is a scalar quantity?
A) Velocity
B) Force
C) Work
D) Acceleration
Answer: C) Work
Explanation: Work is a scalar quantity because it has only magnitude, not direction. It is defined as the force applied to an object times the distance over which the force is applied.
5. Which one of the following is a fundamental quantity?
A) Velocity
B) Force
C) Mass
D) Power
Answer: C) Mass
Explanation: Mass is a fundamental physical quantity, meaning it is not defined in terms of other quantities. It is one of the seven base units in the SI system.
6. Which of the following is the smallest unit of length?
A) Nanometer
B) Micrometer
C) Millimeter
D) Centimeter
Answer: A) Nanometer
Explanation: A nanometer (nm) is one-billionth of a meter (10^-9 meters), making it the smallest unit of length listed.
7. The quantity that has both magnitude and direction is known as?
A) Scalar
B) Vector
C) Force
D) Energy
Answer: B) Vector
Explanation: A vector quantity has both magnitude and direction. Examples include displacement, velocity, and force.
8. The physical quantity that represents the rate of change of momentum is?
A) Energy
B) Power
C) Force
D) Work
Answer: C) Force
Explanation: According to Newton’s second law, force is the rate of change of momentum. Mathematically, F=dpdtF = \frac{dp}{dt}F=dtdp, where ppp is momentum.
9. The standard unit of electric current is?
A) Volt
B) Ampere
C) Coulomb
D) Ohm
Answer: B) Ampere
Explanation: The Ampere (A) is the SI unit of electric current. It is defined as the flow of electric charge through a conductor.
10. Which of the following is not a vector quantity?
A) Displacement
B) Force
C) Velocity
D) Temperature
Answer: D) Temperature
Explanation: Temperature is a scalar quantity as it has only magnitude and no direction.
11. A system of units that is based on fundamental physical quantities is called?
A) C.G.S. system
B) M.K.S. system
C) SI system
D) FPS system
Answer: C) SI system
Explanation: The SI (International System of Units) is a modern system of units based on seven fundamental quantities: length, mass, time, electric current, temperature, amount of substance, and luminous intensity.
12. Which of the following is used to measure temperature?
A) Thermometer
B) Barometer
C) Anemometer
D) Calorimeter
Answer: A) Thermometer
Explanation: A thermometer is used to measure temperature, often based on the expansion of liquids or the resistance of materials.
13. The system of measurement used in most of the world is the?
A) Imperial system
B) Metric system
C) SI system
D) FPS system
Answer: C) SI system
Explanation: The SI system (International System of Units) is used worldwide, except in a few countries like the United States, which still use the Imperial system.
14. The dimensional formula for force is?
A) [M1L1T−2][M^1 L^1 T^{-2}][M1L1T−2]
B) [M1L2T−3][M^1 L^2 T^{-3}][M1L2T−3]
C) [M1L0T−2][M^1 L^0 T^{-2}][M1L0T−2]
D) [M2L1T−1][M^2 L^1 T^{-1}][M2L1T−1]
Answer: A) [M^1 L^1 T^{-2}]
Explanation: The dimensional formula for force can be derived from Newton’s second law, F=maF = maF=ma, where mass (m) has the dimensional formula [M][M][M] and acceleration (a) has the formula [LT−2][L T^{-2}][LT−2], so the formula for force becomes [M1L1T−2][M^1 L^1 T^{-2}][M1L1T−2].
15. The SI unit of energy is?
A) Joule
B) Newton
C) Watt
D) Calorie
Answer: A) Joule
Explanation: The Joule (J) is the SI unit of energy, and it is defined as the energy expended when a force of one newton is applied over a distance of one meter.
16. Which of the following is a derived unit?
A) Kilogram
B) Meter
C) Ampere
D) Newton
Answer: D) Newton
Explanation: The Newton (N) is a derived unit, representing force, and is defined as 1 N=1 kg⋅m/s21 \, \text{N} = 1 \, \text{kg} \cdot \text{m/s}^21N=1kg⋅m/s2.
17. The phenomenon of refraction is due to the change in the?
A) Speed of light
B) Direction of light
C) Frequency of light
D) Wavelength of light
Answer: A) Speed of light
Explanation: Refraction occurs when light passes from one medium to another, causing a change in speed, which leads to a change in direction.
18. The unit of force in the SI system is?
A) Pascal
B) Newton
C) Joule
D) Watt
Answer: B) Newton
Explanation: The Newton (N) is the SI unit of force and is defined as the amount of force required to accelerate a 1 kg mass by 1 m/s².
19. The International System of Units (SI) was established in?
A) 1860
B) 1960
C) 1940
D) 1900
Answer: B) 1960
Explanation: The SI system was officially adopted in 1960 by the International System of Weights and Measures.
20. The quantity that remains constant during a free fall is?
A) Velocity
B) Acceleration
C) Displacement
D) Force
Answer: B) Acceleration
Explanation: During free fall, the acceleration due to gravity remains constant (approximately 9.8 m/s² near the Earth’s surface), whereas velocity and displacement change.
21. Which of the following is the correct SI unit for measuring force?
A) Joule
B) Watt
C) Newton
D) Pascal
Answer: C) Newton
Explanation: The SI unit for force is the Newton (N), defined as the force required to accelerate a 1 kg mass by 1 meter per second squared.
22. What is the dimensional formula of velocity?
A) [M^1 L^1 T^−1]
B) [M^0 L^1 T^−1]
C) [M^1 L^0 T^−1]
D) [M^1 L^1 T^−2]
Answer: B) [M^0 L^1 T^−1]
Explanation: Velocity is defined as displacement/time, where displacement has the dimensional formula [L][L][L] and time has the dimensional formula [T][T][T], resulting in [M0L1T−1][M^0 L^1 T^{-1}][M0L1T−1].
23. The mass of an object can be measured using which of the following instruments?
A) Calorimeter
B) Spring balance
C) Beam balance
D) Thermometer
Answer: C) Beam balance
Explanation: A beam balance is used to measure the mass of an object by comparing it with known masses.
24. The prefix “kilo-” represents a factor of?
A) 100
B) 1,000
C) 10,000
D) 10
Answer: B) 1,000
Explanation: The prefix “kilo-” represents a factor of 1,000 (10^3), so 1 kilometer (km) = 1,000 meters.
25. The base unit of temperature in the SI system is?
A) Celsius
B) Kelvin
C) Fahrenheit
D) Joule
Answer: B) Kelvin
Explanation: The base unit of temperature in the SI system is the Kelvin (K). Zero Kelvin represents absolute zero, the lowest possible temperature.
26. Which of the following is an example of a derived quantity?
A) Time
B) Length
C) Speed
D) Mass
Answer: C) Speed
Explanation: Speed is a derived quantity because it is defined as distance divided by time, both of which are measured in base units.
27. What does the term “dimension” refer to in physics?
A) The physical quantity itself
B) The units of the quantity
C) The mathematical relationship between physical quantities
D) The structure of the physical world
Answer: B) The units of the quantity
Explanation: In physics, the dimension of a physical quantity refers to the units that represent that quantity in terms of the fundamental units of mass, length, and time.
28. The measurement of length in the C.G.S. system is done in?
A) Millimeters
B) Centimeters
C) Meters
D) Kilometers
Answer: B) Centimeters
Explanation: The Centimeter-Gram-Second (C.G.S.) system uses the centimeter (cm) as the unit for length.
29. Which of the following is not a fundamental physical quantity?
A) Length
B) Time
C) Electric current
D) Density
Answer: D) Density
Explanation: Density is a derived physical quantity because it is defined as mass per unit volume, both of which are fundamental quantities.
30. A physical quantity that has both magnitude and direction is called?
A) Scalar
B) Vector
C) Constant
D) Derivative
Answer: B) Vector
Explanation: A vector has both magnitude and direction, like velocity, force, and displacement.
31. Which of the following is the smallest unit of mass?
A) Milligram
B) Gram
C) Kilogram
D) Microgram
Answer: D) Microgram
Explanation: A microgram (µg) is one-millionth of a gram (10^-6 g), making it the smallest unit of mass listed.
32. The quantity that remains constant for an ideal gas during isothermal processes is?
A) Temperature
B) Volume
C) Pressure
D) Energy
Answer: A) Temperature
Explanation: During an isothermal process, the temperature remains constant, while the pressure and volume may change.
33. What is the SI unit of work?
A) Watt
B) Joule
C) Newton
D) Pascal
Answer: B) Joule
Explanation: Work is measured in joules (J), which is the energy transferred when a force of one newton moves an object one meter.
34. The standard unit of power in the SI system is?
A) Watt
B) Joule
C) Newton
D) Ampere
Answer: A) Watt
Explanation: Power is measured in watts (W), which represents the rate at which energy is transferred or converted, defined as 1 joule per second.
35. The unit of measurement for pressure in the SI system is?
A) Pascal
B) Newton
C) Joule
D) Watt
Answer: A) Pascal
Explanation: The SI unit for pressure is the Pascal (Pa), which is defined as one newton per square meter (N/m²).
36. A meter is defined as the distance travelled by light in?
A) 1/60 of a second
B) 1/299,792,458 seconds
C) 1/1,000,000 seconds
D) 1/100 of a second
Answer: B) 1/299,792,458 seconds
Explanation: A meter is defined as the distance that light travels in a vacuum in 1/299,792,458 seconds, which is the speed of light.
37. The velocity of light in vacuum is approximately?
A) 3 × 10^8 m/s
B) 3 × 10^6 m/s
C) 3 × 10^9 m/s
D) 3 × 10^10 m/s
Answer: A) 3 × 10^8 m/s
Explanation: The speed of light in vacuum is approximately 3 × 10^8 meters per second, which is a fundamental constant in physics.
38. Which of the following is a derived SI unit?
A) Meter
B) Kilogram
C) Ampere
D) Volt
Answer: D) Volt
Explanation: Volt (V) is the SI unit of electric potential and is a derived unit, defined as 1 joule per coulomb (1 V = 1 J/C).
39. The fundamental SI unit for electric charge is?
A) Ampere
B) Coulomb
C) Volt
D) Ohm
Answer: B) Coulomb
Explanation: The SI unit for electric charge is the Coulomb (C), which is the amount of charge transported by a current of one ampere in one second.
40. The dimensional formula of energy is?
A) [M^1 L^2 T^-2]
B) [M^1 L^2 T^-1]
C) [M^2 L^1 T^-2]
D) [M^0 L^2 T^-2]
Answer: A) [M^1 L^2 T^-2]
Explanation: Energy, in the form of work or kinetic energy, has the dimensional formula [M^1 L^2 T^-2], as derived from the equation Energy=12mv2\text{Energy} = \frac{1}{2}mv^2Energy=21mv2.
41. Which of the following quantities is a scalar?
A) Force
B) Displacement
C) Velocity
D) Work
Answer: D) Work
Explanation: Work is a scalar quantity because it does not have a direction associated with it, only magnitude.
42. The SI unit of frequency is?
A) Hertz
B) Watt
C) Joule
D) Newton
Answer: A) Hertz
Explanation: Frequency, which refers to the number of oscillations per second, is measured in hertz (Hz), where 1 Hz = 1 oscillation per second.
43. The unit of acceleration is?
A) m/s
B) m/s²
C) m²/s
D) m/s³
Answer: B) m/s²
Explanation: Acceleration is the rate of change of velocity with time, so its unit is meters per second squared (m/s²).
44. The dimension of force is?
A) [M L T^-2]
B) [M^2 L T^-1]
C) [M L T^-1]
D) [M L T^-3]
Answer: A) [M L T^-2]
Explanation: The dimensional formula for force is derived from Newton’s second law, F=maF = maF=ma, where mmm has the dimension [M], and aaa has the dimension [L T^-2].
45. Which of the following is an example of a fundamental unit?
A) Speed
B) Mass
C) Density
D) Force
Answer: B) Mass
Explanation: Mass is a fundamental quantity and has its own SI unit, the kilogram (kg).
46. The SI unit of energy is named after which scientist?
A) Isaac Newton
B) Albert Einstein
C) James Prescott Joule
D) Michael Faraday
Answer: C) James Prescott Joule
Explanation: The unit of energy, the joule (J), is named after the British physicist James Prescott Joule, who studied the relationship between heat and mechanical work.
47. The quantity that defines the motion of an object in relation to time is called?
A) Displacement
B) Velocity
C) Acceleration
D) Speed
Answer: B) Velocity
Explanation: Velocity describes the rate at which an object changes its position, including direction, relative to time.
48. A particle moves with constant velocity. Its acceleration is?
A) Zero
B) Constant
C) Increasing
D) Decreasing
Answer: A) Zero
Explanation: If the velocity is constant, there is no change in speed or direction, so the acceleration is zero.
49. The principle behind the working of a thermometer is?
A) Expansion of solids
B) Expansion of liquids
C) Expansion of gases
D) All of the above
Answer: B) Expansion of liquids
Explanation: In most thermometers, the liquid (often mercury or alcohol) expands as the temperature increases, providing a reading of the temperature.
50. The force of attraction between two masses is directly proportional to?
A) The sum of their masses
B) The difference of their masses
C) The product of their masses
D) The square of the distance between them
Answer: C) The product of their masses
Explanation: According to Newton’s law of gravitation, the gravitational force between two masses is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.
This concludes the 50 MCQs on Unit 1: Physical World and Measurement. Understanding these foundational concepts is essential for building a solid base in Physics. Whether you’re preparing for an exam or seeking to understand the core principles of physical measurements, practicing with MCQs can enhance your knowledge and analytical skills.
Feel free to revisit these questions for a better grasp on topics like units, dimensions, fundamental quantities, and physical laws. Happy studying!
Also Read : 50 MCQs on Unit 2: Kinematics
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