Exam-Focused MCQs for CBSE Class 12 Physics Board Exams
Exam‑Focused MCQs for CBSE Class 12 Physics Board Exams
Class: 12
Subject: Physics
Section: 10 – Experimental Skills
Topic: Exam‑Focused MCQs
Board: CBSE Board Examinations
Subject: Physics
Section: 10 – Experimental Skills
Topic: Exam‑Focused MCQs
Board: CBSE Board Examinations
Instructions: These Multiple Choice Questions (MCQs) are designed strictly as per the NCERT syllabus, making them ideal for CBSE Class 12 Board Examination standards. Questions emphasize practical application, graphical analysis, error calculation, and instrument handling.
1. The balancing length in a potentiometer is directly proportional to:
Answer: B
Explanation: Potential difference ∝ balancing length since potential gradient is constant along the wire.
Explanation: Potential difference ∝ balancing length since potential gradient is constant along the wire.
2. Sensitivity of a potentiometer increases when:
Answer: C
Explanation: Smaller gradient → larger balancing length → higher sensitivity.
Explanation: Smaller gradient → larger balancing length → higher sensitivity.
3. Internal resistance of a cell is measured using:
Answer: C
Explanation: Potentiometer compares emf and terminal voltage to calculate internal resistance accurately.
Explanation: Potentiometer compares emf and terminal voltage to calculate internal resistance accurately.
4. Percentage error is calculated as:
Answer: A
Explanation: Standard definition used in experimental measurements.
Explanation: Standard definition used in experimental measurements.
5. A galvanometer detects:
Answer: B
Explanation: It is a sensitive current detector, especially for null methods.
Explanation: It is a sensitive current detector, especially for null methods.
6. In meter bridge, jockey should touch the wire:
Answer: B
Explanation: Heavy contact heats the wire and changes resistance.
Explanation: Heavy contact heats the wire and changes resistance.
7. Which graph verifies Ohm’s law?
Answer: B
Explanation: Linear relation confirms V ∝ I.
Explanation: Linear relation confirms V ∝ I.
8. Main source of systematic error:
Answer: B
Explanation: Calibration defects introduce consistent error.
Explanation: Calibration defects introduce consistent error.
9. Accuracy improves by:
Answer: B
Explanation: Averaging reduces random error.
Explanation: Averaging reduces random error.
10. SI unit of emf:
Answer: B
Explanation: emf is potential difference → Volt.
Explanation: emf is potential difference → Volt.
11. Slope of resistance vs length graph gives:
Answer: B
Explanation: From R = ρL/A.
Explanation: From R = ρL/A.
12. Which reduces heating error?
Answer: B
Explanation: Prevents temperature rise affecting resistance.
Explanation: Prevents temperature rise affecting resistance.
13. Log graph is used to find:
Answer: A
Explanation: Log plotting converts power law into straight line.
Explanation: Log plotting converts power law into straight line.
14. Unit of least count:
Answer: A
Explanation: It depends on instrument measurement unit.
Explanation: It depends on instrument measurement unit.
15. Which instrument has highest precision?
Answer: C
Explanation: Least count is smallest → highest precision.
Explanation: Least count is smallest → highest precision.
16. Significant figures depend on:
Answer: B
Explanation: More precise instrument → more significant digits.
Explanation: More precise instrument → more significant digits.
17. Error propagation occurs in:
Answer: C
Explanation: Errors combine differently in operations.
Explanation: Errors combine differently in operations.
18. A null deflection means:
Answer: B
Explanation: Balanced condition → no current flow.
Explanation: Balanced condition → no current flow.
19. Intercept on Y‑axis indicates:
Answer: A
Explanation: Non‑zero intercept shows systematic offset.
Explanation: Non‑zero intercept shows systematic offset.
20. Best method to reduce observational error:
Answer: B
Explanation: Proper eye alignment avoids parallax.
Explanation: Proper eye alignment avoids parallax.
