VITEEE 2009 Paper

When both the wires vibrate simultaneously, beats per second,
n1±n2=6
or

1

2l

√

T

m

±

1

2l

√

T'

m

=6⇒

1

2l

√

T'

m

−

1

2l

√

T

m

=6
⇒

1

2l

√

T'

m

−600=6⇒

1

2l

√

T'

m

=606...(i)
Given that fundamental frequency

1

2l

√

T

m

=600...(ii)
Dividing Eq.(i) by (ii),

1 2l √ T' m

1 2l √ T m

=

606

600

⇒ √

T'

T

=(1.01)⇒

T'

T

=(1.02)%⇒T'=T(1.02)
Increase in tension
ΔT' = T×1.02 - T = (0.02T)
∴ ΔT = 0.02