Units and Measurement (1st PUC)

5 practice questions on Units and Measurement (1st PUC) for KCET, with answers

Shishya's practice questions, written with AI. Each answer was checked by an automated second pass, not by a person.

1. 1.The SI unit of luminous intensity is

   • (A)Lumen
   • (B)Candela
   • (C)Lux
   • (D)Watt
   Show the answer and solution

   Answer: (B) Candela

   Solution: Candela (cd) is the SI base unit of luminous intensity. Lumen is the unit of luminous flux, and lux is the unit of illuminance.

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2. 2.The dimensional formula for force is

   • (A)[MLT^-2]
   • (B)[MLT^-1]
   • (C)[ML^2T^-2]
   • (D)[ML^2T^-1]
   Show the answer and solution

   Answer: (A) [MLT^-2]

   Solution: Force = mass × acceleration = M × LT^-2 = [MLT^-2]. This dimensional formula is obtained from Newton's second law.

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3. 3.If the unit of length is doubled and the unit of time is halved, the unit of velocity becomes:

   • (A)Same as before
   • (B)Doubled
   • (C)Four times
   • (D)Half
   Show the answer and solution

   Answer: (C) Four times

   Solution: Velocity = length/time. If length unit doubles and time unit is halved, new velocity unit = (2L)/(T/2) = 4(L/T), which is four times the original.

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4. 4.A physical quantity X is related to four measurable quantities a, b, c, and d as X = a²b³/cd. The percentage error in X is

   • (A)Δa/a + Δb/b + Δc/c + Δd/d
   • (B)2Δa/a + 3Δb/b + Δc/c + Δd/d
   • (C)2Δa/a + 3Δb/b - Δc/c - Δd/d
   • (D)(Δa/a)² + (Δb/b)³ + Δc/c + Δd/d
   Show the answer and solution

   Answer: (B) 2Δa/a + 3Δb/b + Δc/c + Δd/d

   Solution: For X = a²b³/cd, the percentage error is ΔX/X = 2(Δa/a) + 3(Δb/b) + (Δc/c) + (Δd/d), where powers become coefficients and division terms are added.

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5. 5.The percentage error in the measurement of mass and speed are 2% and 3% respectively. The maximum percentage error in the calculation of kinetic energy is:

   • (A)5%
   • (B)8%
   • (C)10%
   • (D)12%
   Show the answer and solution

   Answer: (B) 8%

   Solution: Kinetic energy KE = ½mv². The percentage error in KE is given by ΔKE/KE = Δm/m + 2(Δv/v) = 2% + 2(3%) = 2% + 6% = 8%.

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