Question

1. the parallel branch with a changed component value

a does not allow current
b changes ( z_t, i_t ), and voltage drops
c eliminates the effect of the changed component value
d measures the applied voltage across the changed component value

Explanation:

In a parallel circuit, if a component's value in a branch changes, the total impedance \( Z_T \) (since parallel impedance is calculated from individual branches), total current \( I_T \) (as \( I_T=\frac{V}{Z_T} \) where \( V \) is the source voltage, and \( Z_T \) changes), and voltage drops (though voltage across parallel branches is equal to source voltage, but if \( Z_T \) changes, \( I_T \) changes and current distribution in branches may change, affecting voltage drops in a more complex analysis) are affected. Option a is wrong as parallel branches with changed components still allow current. Option c is wrong as the change in component value does have an effect. Option d is wrong as a parallel branch doesn't "measure" voltage; voltage across parallel branches is equal to source voltage by nature of parallel circuits. So option b is correct.

Answer:

b. changes \( Z_T \), \( I_T \), and voltage drops