PH 122 Lecture Notes - Root Mean Square, Transcranial Magnetic Stimulation

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lemondog142

25 Mar 2014

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Transformers are used to increase or decrease an ac voltage. The rms voltage at the secondary is related to the rms voltage on the primary by. N 1 (v1)rms and the currents are related by (i2)rms = A power pack for a portable stereo delivers 1. 0 a at a voltage of 9. 0 v under normal operation. It has 400 turns of wire on the primary coil. P = iv = (1. 0 a) (9. 0 v) = 9. 0 w. Power should be the same in the primary and secondary. The downward flux in one end is increasing. The downward flux in the other end is decreasing. The change in flux in the ends induce eddy currents in the metal. The magnetic field exerts a force on the eddy currents in the direction opposite the motion. A large current is quickly switch on, a magnetic field penetrates the brain, and resulting rapid change in flux induces eddy currents in brain tissues.

Related Questions

An AC adaptor for a telephone answering unit uses a transformer toreduce the line voltage of 143 V (rms) to a voltage 7.7 V. The rmscurrent delivered to a answering system is 433 mA.

Part 1) If the primary (input) coil in the transformer in theadaptor has 110 turns, how many turns are there on the secondary(output) coil?
Answer in units of turns.

Part 2) What is the rms power delivered to the transformer? Assumean ideal transformer.
Answer in units of W.

Suppose there are two transformers between your house and the high-voltage transmission line that distributes the power. In addition, assume that your house is the only one using electric power. At a substation, the primary of a step-down transformer (turns ratio = 1:29) receives the voltage from the high-voltage transmission line. Because of your usage, a current of 48.0 mA exists in the primary of this transformer. The secondary is connected to the primary of another step-down transformer (turns ratio = 1:32) somewhere near your house, perhaps up on a telephone pole. The secondary of this transformer delivers a 240 V emf to your house. How much power is your house using? Remember that the current and voltage given in this problem are rms values.

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Suppose there are two transformers between yout house and the high-voltage transmission line that distributes the power. In addition, assume your house is the only one using electric power. At a substation the primary of a step-down transformer (turns ratio = 1:29) receives the voltage from the high-voltage transmission line. Because of your usage, a current of 48mA exists in the primary of this transformer. The secondary is connected to the primary of another step-down transformer (turns ratio 1:32) somewhere near your house, perhaps up on a telephone pole. The secondary of this transformer delivers a 240V emf to your house. How much power is your house using? Remember that the current and voltage given in this problem are rms values.

PH 122 Lecture Notes - Root Mean Square, Transcranial Magnetic Stimulation

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