CSS - PMS - CCE - PCS - General Science
Electricity & Magnetism - Transformers
Why are transformers important in power transmission?
A. They stop electric fields
B. They generate fuel
C. They eliminate all losses completely
D. High-voltage transmission can reduce current and resistive losses for a given power
Correct Answer: D
Stepping voltage up lowers current, reducing I²R line losses.
CSS - PMS - CCE - PCS - General Science
Electricity & Magnetism - Transformers
For an ideal transformer, Vp/Vs equals what ratio?
A. Np/Ns
B. fp/fs
C. Is/Ip only in the same direction
D. Rp/Rs always
Correct Answer: A
Voltage ratio equals turns ratio for an ideal transformer.
CSS - PMS - CCE - PCS - General Science
Electricity & Magnetism - Transformers
Why do ordinary transformers require alternating current?
A. Transformers need no magnetic field
B. AC contains no electrons
C. DC has too much frequency
D. A changing current produces changing magnetic flux needed for induction
Correct Answer: D
Constant DC does not continuously induce emf in the secondary after transients die out.
CSS - PMS - CCE - PCS - General Science
Electricity & Magnetism - Transformers
A step-down transformer does what to voltage?
A. Converts AC to DC directly
B. Increases it
C. Decreases it
D. Always doubles frequency
Correct Answer: C
A step-down transformer has fewer secondary turns than primary turns.
CSS - PMS - CCE - PCS - General Science
Electricity & Magnetism - Transformers
A step-up transformer does what to voltage?
A. Increases it
B. Keeps it at zero
C. Decreases it
D. Converts it to heat only
Correct Answer: A
A step-up transformer has more turns on the secondary than the primary.
CSS - PMS - CCE - PCS - General Science
Electricity & Magnetism - Transformers
What is the main function of a transformer?
A. Convert DC directly without switching
B. Change AC voltage and current levels by electromagnetic induction
C. Store chemical energy
D. Measure temperature
Correct Answer: B
Transformers transfer AC power between coils through a changing magnetic flux.