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1. A quantity that can be measured and expressed in terms of a numerical value and a unit is called a:
A. Physical quantity
B. Fundamental quantity only
C. Derived quantity only
D. Dimensionless quantity
Answer: A. Physical quantity
Explanation: A physical quantity is any quantity that can be measured, expressed using a number along with an appropriate unit.
2. The internationally accepted system of units used in scientific measurement is called the:
A. SI system (International System of Units)
B. FPS system
C. CGS system only
D. Metric system only, unrelated to SI
Answer: A. SI system (International System of Units)
Explanation: The SI (Système International) system is the standardised, globally accepted system of units used in science and measurement.
3. The SI unit of length is the:
A. Metre
B. Centimetre
C. Kilometre
D. Foot
Answer: A. Metre
Explanation: The metre is defined as the base SI unit for measuring length.
4. The SI unit of mass is the:
A. Kilogram
B. Gram
C. Pound
D. Tonne
Answer: A. Kilogram
Explanation: The kilogram is the fundamental SI unit used for measuring mass.
5. The SI unit of time is the:
A. Second
B. Minute
C. Hour
D. Day
Answer: A. Second
Explanation: The second is defined as the base SI unit for measuring time.
6. The number of fundamental (base) quantities in the SI system is:
A. Seven
B. Five
C. Three
D. Ten
Answer: A. Seven
Explanation: The SI system defines seven fundamental base quantities: length, mass, time, electric current, temperature, amount of substance, and luminous intensity.
7. Quantities that are expressed in terms of the base quantities are called:
A. Derived quantities
B. Fundamental quantities
C. Scalar quantities only
D. Dimensionless quantities
Answer: A. Derived quantities
Explanation: Derived quantities, such as speed or force, are obtained by combining base quantities through mathematical relations.
8. The dimensional formula of velocity is:
A. [M0L1T-1]
B. [M1L1T-1]
C. [M0L1T-2]
D. [M1L0T-1]
Answer: A. [M0L1T-1]
Explanation: Velocity is displacement divided by time, giving a dimensional formula of length (L) divided by time (T), independent of mass.
9. The dimensional formula of force is:
A. [M1L1T-2]
B. [M0L1T-1]
C. [M1L2T-2]
D. [M1L1T-1]
Answer: A. [M1L1T-2]
Explanation: Since force = mass × acceleration, and acceleration has dimensions [LT-2], force has dimensions [M1L1T-2].
10. The dimensional formula of energy (or work) is:
A. [M1L2T-2]
B. [M1L1T-2]
C. [M0L2T-2]
D. [M1L2T-1]
Answer: A. [M1L2T-2]
Explanation: Since energy = force × distance, combining [M1L1T-2] with [L1] gives [M1L2T-2].
11. The principle of homogeneity of dimensions states that in a valid physical equation, both sides must have:
A. The same dimensions
B. The same numerical value only
C. Different units
D. No relation to each other
Answer: A. The same dimensions
Explanation: This principle requires that all terms in a physically meaningful equation possess identical dimensions on both sides.
12. Dimensional analysis is useful for:
A. Checking the correctness of physical equations and deriving relationships between quantities
B. Measuring exact numerical values only
C. Determining the colour of an object
D. Predicting biological outcomes
Answer: A. Checking the correctness of physical equations and deriving relationships between quantities
Explanation: Dimensional analysis helps verify equation consistency and can assist in deriving relationships between physical quantities.
13. The error that occurs due to the limitations of a measuring instrument is called:
A. Systematic error
B. Random error only
C. Gross error
D. Personal error only
Answer: A. Systematic error
Explanation: Systematic errors arise from consistent flaws in instruments or experimental methods, causing measurements to deviate in a predictable direction.
14. Errors that occur irregularly due to unpredictable fluctuations in experimental conditions are called:
A. Random errors
B. Systematic errors
C. Instrumental errors only
D. Gross errors
Answer: A. Random errors
Explanation: Random errors arise from unpredictable variations, causing measurements to fluctuate above and below the true value irregularly.
15. The number of significant figures in the measurement 0.0025 m is:
A. Two
B. Four
C. Five
D. Three
Answer: A. Two
Explanation: Leading zeros are not significant; only the digits 2 and 5 count, giving two significant figures.
16. The number of significant figures in the measurement 2.500 m is:
A. Four
B. Two
C. One
D. Three
Answer: A. Four
Explanation: Trailing zeros after a decimal point are significant, so 2.500 has four significant figures: 2, 5, 0, 0.
17. The closeness of a measured value to the true value is called:
A. Accuracy
B. Precision
C. Least count
D. Significant figures
Answer: A. Accuracy
Explanation: Accuracy refers to how close a measured value is to the actual or true value of the quantity being measured.
18. The degree to which repeated measurements under the same conditions show consistent results is called:
A. Precision
B. Accuracy
C. Error
D. Uncertainty only
Answer: A. Precision
Explanation: Precision refers to the consistency or reproducibility of measurements, regardless of how close they are to the true value.
19. The smallest value that can be measured accurately by a measuring instrument is called its:
A. Least count
B. Range
C. Error
D. Precision
Answer: A. Least count
Explanation: The least count of an instrument represents the smallest measurable increment it can accurately record.
20. The order of magnitude of a physical quantity is determined by expressing it as a power of:
A. 10
B. 2
C. e (Euler's number)
D. 100
Answer: A. 10
Explanation: Order of magnitude estimation rounds a value to the nearest power of 10, providing an approximate scale of the quantity.
21. If a physical quantity Z = A × B, then the relative error in Z is calculated by:
A. Adding the relative errors in A and B
B. Subtracting the relative errors
C. Multiplying the relative errors
D. Dividing the relative errors
Answer: A. Adding the relative errors in A and B
Explanation: For quantities combined by multiplication, the relative (percentage) errors of each individual quantity are added together.
22. The dimensions of Planck's constant are the same as those of:
A. Angular momentum
B. Force
C. Energy only
D. Velocity
Answer: A. Angular momentum
Explanation: Planck's constant has the dimensional formula [M1L2T-1], which matches the dimensions of angular momentum.
23. Which of the following pairs has the same dimensions?
A. Work and Energy
B. Force and Pressure
C. Velocity and Acceleration
D. Mass and Weight
Answer: A. Work and Energy
Explanation: Both work and energy share the identical dimensional formula [M1L2T-2], since work done is a measure of energy transfer.
24. A dimensionless quantity is one that:
A. Has no associated physical dimension, such as strain or refractive index
B. Cannot be measured at all
C. Always equals zero
D. Only applies to time measurements
Answer: A. Has no associated physical dimension, such as strain or refractive index
Explanation: Dimensionless quantities, like strain or angle in radians, are ratios of similar quantities and hence have no associated dimension.
25. The parallax method is used in physics primarily to measure:
A. Large distances, such as to stars or planets
B. Small time intervals
C. Electric current
D. Mass of subatomic particles
Answer: A. Large distances, such as to stars or planets
Explanation: The parallax method uses the apparent shift in position of a distant object to calculate large astronomical distances.
26. Which of the following instruments is used to measure very small lengths with high precision?
A. Vernier callipers
B. Metre scale
C. Odometer
D. Stopwatch
Answer: A. Vernier callipers
Explanation: Vernier callipers provide a higher degree of precision for measuring small lengths compared to a standard metre scale.
27. The screw gauge is typically used to measure:
A. The diameter of very thin wires or small objects
B. Large distances between cities
C. Time intervals
D. Temperature
Answer: A. The diameter of very thin wires or small objects
Explanation: A screw gauge, offering very fine precision, is specifically designed to measure extremely small lengths like wire diameters.
28. If the length of a rod is measured as 25.0 cm using an instrument with a least count of 0.1 cm, the reported value reflects:
A. The precision limit of the measuring instrument used
B. An exact, error-free measurement
C. A random guess
D. An average of many different instruments
Answer: A. The precision limit of the measuring instrument used
Explanation: The number of significant figures reported in a measurement reflects the least count and hence the precision of the instrument used.
29. Which of the following represents a correct example of dimensional consistency?
A. Comparing the dimensions of kinetic energy (1/2 mv²) with potential energy (mgh)
B. Comparing mass with time directly
C. Comparing length with temperature directly
D. Adding velocity and acceleration directly
Answer: A. Comparing the dimensions of kinetic energy (1/2 mv²) with potential energy (mgh)
Explanation: Both kinetic energy and potential energy share the same dimensional formula [M1L2T-2], demonstrating dimensional consistency between different forms of energy.
30. The main purpose of using significant figures in a measurement is to:
A. Indicate the precision and reliability of the recorded measurement
B. Make numbers appear larger
C. Simplify all calculations to whole numbers
D. Avoid using any units altogether
Answer: A. Indicate the precision and reliability of the recorded measurement
Explanation: Significant figures convey the degree of precision achieved during measurement, indicating how reliable a given numerical value is.
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