A step-down transformer is used on a 2.2 kV line to deliver 110 V. How many turns are on the primary windings if the secondary has 25 turns?
A
20
B
250
C
200
D
500
Verified Correct Answer: D.
Physical Principles & Numerical Solution
Ep = 2.2kV = 2200V; Es=110V; Ns=25; Np=?
=\(\frac{E_p}{E_s}\) = \(\frac{N_p}{N_s}\)
= \(\frac{2200}{110}\) = \(\frac{N_p}{25}\)
=110 \times Np = 2200 \times 25
=\(N_p\) = \(\frac{55,000}{110}\)
∴\(N_p\) = 500 turns
Source: WAEC / JAMB / NECO Classroom Archive (Record #68000)