(if you could help me answer even one,..)
1. The primary coil of a transformer makes 240 turns around the iron core, and the secondary coil of that transformer makes 80 turns. If the primary voltage is 120 V, why will the secondary voltage be only 40 V?
2. Why does a magnet stick to the surface of a refrigerator?
3. When you have the magnetic strip on an ID or credit card read, it's always done by moving the card past a playback head. Why must the card be moving for the head to read it?
4. partscoretotalsubmissions1--100/1What does exposing the magnetic strip of an ID or credit card to a strong magnetic field do to that strip that makes it unreadable?
thank you in advance
2007-11-02 18:51:43 · 2 answers · asked by smile_swj 1 in Science & Mathematics ➔ Physics
1.Voltage is proportional to the number of turns. So, 240/80 is same as 120/40 and that is 3.
2. Refrigerator is made of steel and is magnetic. So magnet sticks.
3. Since the head is fixed, card has to move.
4. Yes. It may become unreadable as the magnetic code gets damaged.
2007-11-02 19:34:34 · answer #1 · answered by Swamy 7 · 0⤊ 0⤋
1. The induced voltage in a transformer varies directly with the number of turns.
So, v[p]/v[s] = N[p]/N[s]
v[s] = (N[s]/N[p]) v[p] = (80/240)120= 40v
2. The magnet sticks to the surface of the refrigerator because the body of refrigerator is made of steel sheet which is magnetic material.
3. You have to swipe it, so as to read all the information in the strip.
4. No info on that.
2007-11-03 02:38:59 · answer #2 · answered by Anonymous · 0⤊ 0⤋