Electromagnetism Questions Answers
1) 2V x 30/10 = 6V
2) 100Vx2/20=10V
3)6/220=?/10
Number of turns=27
4) It is transmitted at high voltage so that the current is lower for a given power. This means less energy is wasted as heat from the resistance of the wires.
5) i)220x40/3200=2.75V
ii)V=IR, I=2.75/15 =0.18A
iii)P=VI, Power in secondary = 2.75x0.18=0.5W
This must be the same power in the primary. So current=P/V = 0.5/220=0.002A
iv) 0V, transformers do not work with a DC power supply: it needs to be a changing magnetic field.
2) 100Vx2/20=10V
3)6/220=?/10
Number of turns=27
4) It is transmitted at high voltage so that the current is lower for a given power. This means less energy is wasted as heat from the resistance of the wires.
5) i)220x40/3200=2.75V
ii)V=IR, I=2.75/15 =0.18A
iii)P=VI, Power in secondary = 2.75x0.18=0.5W
This must be the same power in the primary. So current=P/V = 0.5/220=0.002A
iv) 0V, transformers do not work with a DC power supply: it needs to be a changing magnetic field.