In a step-up transformer, if the voltage in the secondary is increased, then the current in the primary:

Step-by-step solution

For an ideal transformer, the input power is equal to the output power. V_p I_p = V_s I_s Let a constant load resistance R be connected across the secondary coil. The current in the secondary coil is given by I_s = V_s R . Substituting this into the power equation, we get: V_p I_p = V_s ( V_s R ) V_p I_p = V_s^2 R I_p = V_s^2 V_p R For a constant primary supply voltage V_p and a fixed load resistance R , the primary current I_p is directly proportional to the square of the secondary voltage ( I_p V_s^2 ). Therefore