Question

Time constant is defined as the time required ____. Select one: a. for the deflection to fall (decay) 57% of the peak deflection b. for the deflection to fall (decay) to 47% of the peak deflection c. for the deflection to fall (decay) to 37% of the peak deflection d. for the deflection to fall (decay) 77% of the peak deflection

Answer 1

c. for the deflection to fall (decay) to 37% of the peak deflection

Step-by-step explanation:

For decay of deflection ( in the form of current or voltage ) to decay , the relation is as follows

`i=i_0e^{-(t)/(\lambda)}`

i₀ is maximum current , λ is time constant , i is current at time t .

If t = λ

`i=i_0(e^-(\lambda)/(\lambda) )`

`i=i_0e^(-1)`

i = i₀ x .3678

This tells that time constant is the time during which current ( deflection ) decays to 36.78% of maximum current ( deflection ).