Q.

A student performs an experiment for determination of (g=4π2ℓT2.) The error in length ℓ is Δℓ and in time T is ΔT and n is the number of times the reading is taken. The measurement of g is most accurate for          [2006]

1 Δℓ=5 mm,  ΔT=0.2 sec,  n=10  
2 Δℓ=5 mm,  ΔT=0.2 sec,  n=20  
3 Δℓ=5 mm,  ΔT=0.1 sec,  n=10  
4 Δℓ=1 mm,  ΔT=0.1 sec,  n=50  

Ans.

(4)

Relative error in g,  Δgg=Δℓℓ+2ΔTT

Δℓ and ΔT are least and number of readings taken are maximum in option (d),

∴ the measurement of g is most accurate.