INTERMEDIATE PHYSICS – LESSON 1
UNITS & MEASUREMENTS
Important Questions, Answers & Numericals
🔹 A. VERY SHORT ANSWER QUESTIONS (2 MARKS)
Q1. What is measurement?
Measurement is the process of comparing an unknown physical quantity with a known standard quantity called a unit.
Q2. What is a physical quantity?
A physical quantity is any quantity that can be measured and expressed in terms of a number and a unit.
Q3. What are fundamental quantities?
Fundamental quantities are independent physical quantities which cannot be derived from other quantities.
Q4. Define least count.
Least count is the smallest value that can be measured accurately by a measuring instrument.
Q5. What is dimensional formula?
Dimensional formula expresses a physical quantity in terms of fundamental dimensions such as mass (M), length (L) and time (T).
🔹 B. SHORT ANSWER QUESTIONS (4 MARKS)
Q1. Define SI system and list fundamental units.
SI system is the internationally accepted system of units. It consists of seven fundamental units:
- metre (m)
- kilogram (kg)
- second (s)
- ampere (A)
- kelvin (K)
- mole (mol)
- candela (cd)
Q2. Write the rules of significant figures.
- All non-zero digits are significant
- Zeros between non-zero digits are significant
- Leading zeros are not significant
- Trailing zeros after decimal are significant
Q3. Write uses of dimensional analysis.
- To check correctness of equations
- To convert units
- To derive relations between physical quantities
🔹 C. LONG ANSWER QUESTIONS (8 MARKS)
Q1. Explain errors in measurement.
No measurement is exact. The difference between the true value and the measured value is called error.
- Absolute Error: Difference between measured and true value
- Mean Error: Average of absolute errors
- Percentage Error:
Percentage Error = (Absolute Error / Measured Value) × 100
Errors can be reduced by using precise instruments and taking repeated readings.
🔹 D. NUMERICAL PROBLEMS (VERY IMPORTANT)
Numerical 1: The length of a rod is measured as 5.0 m with an error of 0.1 m. Find percentage error.
Solution:
Percentage Error = (0.1 / 5.0) × 100 = 2%
Numerical 2: Convert 72 km/h into m/s.
Solution:
72 × (5/18) = 20 m/s
Numerical 3: Find the dimensional formula of pressure.
Solution:
Pressure = Force / Area
Force = MLT-2
Area = L2
∴ Pressure = M L-1 T-2
🎯 INTERMEDIATE EXAM TIPS
- Always write units in final answers
- Memorize SI units & symbols
- Practice numerical problems daily
- Draw neat diagrams for instruments
Lesson–1 Complete for Intermediate Exam
Next Lesson: Motion in a Straight Line
Intermediate Physics Complete Notes – IIT JEE & Board Exams
This page contains complete Intermediate Physics notes along with IIT JEE materials, previous year questions, solved problems, diagrams, and exam strategies.
📘 Lesson 1: Units and Measurements
📘 Lesson 2: Motion in a Straight Line
📘 Lesson 3: Motion in a Plane
- Part 1
- Part 2
- Part 3
- Part 4
- Part 5
- Part 6
- Part 7
- Part 8
- Part 9
- Part 10
- Part 11
- Part 12
- Part 13
- Part 14
- Part 15
- Part 16
- Part 17
This page is updated regularly with new lessons.
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