For an undamped system with η = 0, the dynamic magnification factor or amplification factor is ______, where η is damping coefficient, ω is natural frequency and λ is a harmonic force at a frequency.
1
AF = \(\left| {\frac{1}{{\left( {1 - \frac{{{\lambda ^2}}}{{{\omega ^2}}}} \right)}}} \right|\)
2
AF = \(\left| {\frac{1}{{\left( {1 + \frac{{{\lambda ^2}}}{{{\omega ^2}}}} \right)}}} \right|\)
3
AF = \(\left| {\frac{1}{{\left( {1 - \frac{{{\omega ^2}}}{{{\lambda ^2}}}} \right)}}} \right|\)
4
AF = \(\left| {\frac{1}{{\left( {1 + \frac{{{\omega ^2}}}{{{\lambda ^2}}}} \right)}}} \right|\)