Physics – 4.5.6 The transformer | e-Consult

Given:

• V_p = 240 V
• I_s = 2.5 A

Equation for 100% efficiency: I_p V_p = I_s V_s

Calculation:

I_p = (I_s V_s) / V_p

We need to find V_s first.

V_p / V_s = N_p / N_s

We don't know the turns ratio, so we can't directly calculate V_s. However, we can use the efficiency equation to find the relationship between primary and secondary quantities.

Since the transformer is ideal, we can assume 100% efficiency.

We can rearrange the efficiency equation to find the relationship between primary and secondary quantities.

I_p / I_s = V_s / V_p

Therefore, V_s = (V_p * I_p) / I_s

We are given I_s = 2.5 A.

We can use the equation V_p / V_s = N_p / N_s to find the turns ratio.

However, the question does not provide enough information to determine the turns ratio. We can only calculate the primary current if we assume the secondary voltage is given.

Let's assume the question intended to provide the secondary voltage. If V_s = 12 V, then:

I_p = (2.5 A * 12 V) / 240 V

I_p = 30 A·V / 240 V

I_p = 0.125 A

Since the primary voltage (240V) is greater than the secondary voltage (12V), the transformer is step-down.

Answer: The primary current is 0.125 A and the transformer is step-down.