A student measures the length of a rod as 3.50 cm using a vernier caliper with least count 0.01 cm. The number of significant figures in this measurement is: MCQ with Answer and Explanation
A student measures the length of a rod as 3.50 cm using a vernier caliper with least count 0.01 cm. The number of significant figures in this measurement is:
A. 3
B. 1
C. 4
D. 2
Answer: Option A
Solution (By JKSSB Mock Tests)
The measurement 3.50 cm has three significant figures. All non-zero digits (3,5) are significant, and the trailing zero after the decimal point is also significant as it indicates precision of the measuring instrument. The least count of 0.01 cm confirms that the measurement is precise to hundredths place. Significant figures reflect measurement reliability. Exam tip: Trailing zeros after decimal are always significant; leading zeros are never significant. This concept is crucial for error analysis in experimental physics questions.
Explanation:
I_rms defined so I_rms²R = average power, same heating as DC current. For sine wave: I_rms = I₀/√2. Memory tip: 'RMS: heating equivalence; use RMS for power calculations'. AC fundamentals frequently tested in competitive exams.
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