For an ideal step up transformer :

1. $\dfrac{\text {Voltage}$\text{primary}}{\text {Voltage}\text{secondary}} \gt 1 \\[1 em]
2. $\dfrac{\text {Current}$\text{primary}}{\text {Current}\text{secondary}} \lt 1 \\[1 em]
3. $\dfrac{\text {number of turns}$\text{primary}}{\text {number of turns}\text{secondary}} = 1 \\[1 em]
4. $\dfrac{\text {power}$\text{primary}}{\text {power}\text{secondary}} = 1

$\dfrac{\text {power}$\text{primary}}{\text {power}\text{secondary}} = 1

Reason — The step up transformer is used to change a low alternating voltage to a high alternating voltage (of same frequency) i.e.,

V_Secondary > V_Primary

⟹ $\dfrac{\text {Voltage}$\text{secondary}}{\text {Voltage}\text{primary}} \gt 1

Also,

In a step up transformer, the number of turns in the secondary coil is more than the number of turns in the primary coil i.e.,

number of turns_Secondary > number of turns_Primary

⟹ $\dfrac{\text {number of turns}$\text{secondary}}{\text {number of turns}\text{primary}} \gt 1

And

The current in primary coil is more than in the secondary coil i.e.,

Current_primary > Current_secondary

⟹ $\dfrac{\text {Current}$\text{primary}}{\text {Current}\text{secondary}} \gt 1

As, for an ideal transformer, when there is no energy loss, the output power will be equal to the input power. i.e.,

power_primary = power_secondary

⟹ $\dfrac{\text {power}$\text{primary}}{\text {power}\text{secondary}} = 1