Class 11 Physics Physical World and Measurement MCQs (Mixed) with Answers
Physical World and Measurement is the first chapter of Class 11 Physics, and it sets the base for everything you study later. If your units, dimensions, and significant figures are weak, mistakes start happening even in easy numericals. This mixed MCQ set helps you revise the chapter in a focused way: key ideas about the scope of physics, SI base units, errors in measurement, and dimensional analysis. Each question has the correct answer with a short explanation, so you understand the logic instead of memorising.
MCQs (Mixed Practice)
Question 1
Which of the following is not a fundamental force in nature?
A. Gravitational force
B. Electromagnetic force
C. Frictional force
D. Strong nuclear force
Correct Answer: C
Explanation: Fundamental forces are gravitational, electromagnetic, strong nuclear, and weak nuclear. Friction is a contact force that arises due to interactions at surfaces; it is not fundamental.
Question 2
The SI unit of time is defined using which phenomenon?
A. Revolution of the Earth around the Sun
B. Rotation of the Earth about its axis
C. Oscillations of a cesium-133 atom
D. Oscillations of a simple pendulum
Correct Answer: C
Explanation: The second is defined using the frequency of radiation corresponding to the transition between two hyperfine levels of the ground state of cesium-133.
Question 3
Which of the following is the best way to avoid ambiguity in the number of significant figures in a measurement?
A. Write the number without a decimal point
B. Write the number in scientific notation
C. Remove all zeros from the end of the number
D. Convert to smaller units so there are no zeros
Correct Answer: B
Explanation: Scientific notation clearly shows which digits are significant (all digits in the coefficient are significant).
Question 4
If the dimensional formula of a quantity is $[M^1 L^2 T^{-3}]$, it can represent:
A. Power
B. Force
C. Energy
D. Pressure
Correct Answer: A
Explanation: Power = energy/time, so $[M L^2 T^{-2}]/[T] = [M L^2 T^{-3}]$.
Revision Tip: For dimensions, start from a definition you trust (like $v=\frac{s}{t}$, $a=\frac{v}{t}$, $P=\frac{W}{t}$) and build step-by-step.
Question 5
Which of the following correctly represents the dimension of acceleration?
A. $[L T^{-2}]$
B. $[M L T^{-2}]$
C. $[L T]$
D. $[M L^2 T^{-1}]$
Correct Answer: A
Explanation: Acceleration is change in velocity per unit time. Since $v$ is $[L T^{-1}]$, $a$ is $[L T^{-2}]$.
Question 6
Which base quantity is not needed to express the dimensions of force?
A. Mass
B. Length
C. Time
D. Electric current
Correct Answer: D
Explanation: Force $F = m a$ depends on mass, length, and time only: $[M],[L T^{-2}]$.
Question 7
If a physical quantity has dimensions $[M^0 L^0 T^0]$, it is:
A. Dimensionless
B. Dependent only on mass
C. Dependent only on length
D. Dependent only on time
Correct Answer: A
Explanation: Zero powers of all base quantities mean no dimensions (examples: refractive index, strain, coefficient of friction).
Question 8
Assertion (A): The dimensional formula of acceleration is $[M^0 L T^{-2}]$. Reason (R): Acceleration is the rate of change of velocity with respect to time.
A. Both A and R are true and R is the correct explanation of A
B. Both A and R are true but R is not the correct explanation of A
C. A is true but R is false
D. A is false but R is true
Correct Answer: A
Explanation: Velocity is $[L T^{-1}]$. Dividing by time gives $[L T^{-2}]$. The reason states the definition, so it explains the assertion.
Revision Tip: “Dimensionless” does not mean “unitless in a careless way”. It means the quantity is a ratio of two quantities with the same dimensions.
Question 9
Which of the following is the correct set of base units for length, mass, and time in the CGS system?
A. centimetre, gram, second
B. metre, kilogram, second
C. foot, pound, second
D. inch, pound, minute
Correct Answer: A
Explanation: CGS stands for centimetre–gram–second.
Question 10
The candela is the SI unit of:
A. Luminous flux
B. Luminous intensity
C. Electric current
D. Amount of substance
Correct Answer: B
Explanation: Candela (cd) is the SI base unit of luminous intensity.
Prefer level-wise practice? Try the difficulty-wise set: Class 11 Physics Physical World and Measurement MCQs (Difficulty-wise).
If you want to revise one chapter each day, keep practising a small set of MCQs and re-check the explanations where you made mistakes.