Question

If the primary coil of a transformer has 100 turns and the secondary has 200 turns, then for an input of 220 V at 10 A, find the output current in the step-up transformer. 

Hint:

In a step-up transformer, the voltage increases, and the current decreases according to \( I_s = I_p \times \frac{N_p}{N_s} \).

Answer 1

Step 1: Understanding the Transformer Equation 
For a transformer, the relationship between voltage and turns is given by: \[ \frac{V_s}{V_p} = \frac{N_s}{N_p} \] where:
- \( V_p \) and \( V_s \) are the primary and secondary voltages,
- \( N_p \) and \( N_s \) are the number of turns in the primary and secondary coils. Similarly, the current relationship is: \[ \frac{I_s}{I_p} = \frac{N_p}{N_s} \] where \( I_p \) and \( I_s \) are the primary and secondary currents. 
Step 2: Given Data 
- \( N_p = 100 \), \( N_s = 200 \),
- \( V_p = 220 \) V, \( I_p = 10 \) A. 
Step 3: Calculating the Output Current 
Using the current equation: \[ I_s = I_p \times \frac{N_p}{N_s} \] \[ I_s = 10 \times \frac{100}{200} = 10 \times 0.5 = 5 { A} \] 
Step 4: Conclusion 
Since this is a step-up transformer, the voltage increases while the current decreases. The output current is \( 5 \) A.