COMEDK2023Evening ShiftPhysicsAlternating CurrentActual
The current drawn by the primary coil of an ideal transformer, which steps up 22 ~V into 220 ~V , to operate a device having a load resistance 110 is:
Options
- A20 A
- B1 A
- C10 A
- D2 A
Correct answer
A. 20 A
Step-by-step solution
For an ideal transformer, the power input equals the power output. Let V_p and I_p be the primary voltage and current, and V_s and I_s be the secondary voltage and current. Given V_p = 22 V and V_s = 220 V . The load resistance is R = 110 . The secondary current I_s is given by Ohm's law: I_s = V_s R = 220 V 110 = 2 A . Since the transformer is ideal, the power balance equation is V_p I_p = V_s I_s . Substituting the known values: 22 V I_p = 220 V 2 A 22 I_p = 440 I_p = 440 22 = 20 A . Answer: 20 A