A transformer has a primary coil with 400 turns connected to a 240 V AC supply and a secondary coil with 100 turns. If the secondary is connected to a 20 Ω resistor, the power in the secondary circuit is:
Correct answer: B. 180 W
- A. 72 W
- B. 180 W
- C. 288 W
- D. 360 W
Explanation
Voltage ratio Vs/Vp= Ns/Np. Thus, Vs= (100 / 400) × 240 = 60 V. CurrentIs =Vs/R= 60 / 20= 3A.Power P =VsIs=60×3=180 W, but adjusting for ideal transformer power conservation, P = (602/20) = 180 W.
Last updated
About Electromagnetism
Magnetic flux density and magnetic flux describe the strength of a magnetic field and the field passing through a surface. A charged particle moving through a magnetic field experiences a force perpendicular to its velocity and may follow circular or helical motion, depending on the angle between velocity and field.
Practise Electromagnetism
1,176 free Electromagnetism MCQs from Physics, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Exams that ask Physics questions like this
Physics is on 13 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.
Related questions
1 Tesla is equal to:
1 tesla is equal to:
2.5π µF capacitor and 3000-ohm resistance are joined in series to an AC source of 200 volts and frequency. The power factor of the circuit and the power dissipated in it will respectively be:
A 10 cm long solenoid has 100 turns. What will be the magnetic field inside it along its axis if one-microampere current is passed through it?
A 100-turn coil of area 0.1 m2 rotates at half a revolution per second. It is placed in a uniform magnetic field of 0.01 T perpendicular to the axis of rotation of the coil. Calculate the maximum voltage generated in the coil?