WAEC - Physics (1991 - No. 48)
A house is supplied with a 240V a.c mains. To operate a door bell rated at 8v, a transformer is used if the number of turns in the primary coil of the transformer is 900. calculate the number of turns in the secondary coil of the transformer
30
240
248
450
1248
Vysvetlenie
\(\frac{E_p}{E_s} = \frac{n_p}{n_s}\)
ns = 30
ns = 30