Q.

A student performs an experiment for determination of (g=4π2T2.) The error in length  is Δ 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 Δ=5mm,  ΔT=0.2 sec,  n=10  
2 Δ=5 mm,  ΔT=0.2 sec,  n=20  
3 Δ=5 mm,  ΔT=0.1 sec,  n=10  
4 Δ=1 mm,  ΔT=0.1 sec,  n=50  

Ans.

(4)

Relative error in g,  Δgg=Δ+2ΔTT

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

 the measurement of g is most accurate.