Question

A small transformer to recharge the battery in a cell phone is plugged into a wall socket that has 120 volts RMS and a maximum available current of 20 Amps. The secondary coil of the transformer has 14 turns, and the output voltage of the transformer is 5.5V (DC). The recharger takes 440mA out from the transformer. Assume the transformer is ‘ideal’, with and efficiency of 100 percent.

- What is the resistance of the battery recharger from the cell phone?

- How many turns are on the primary coil of the transformer?

- How much power is coming out from the transformer, into the recharger?

- How much current from the wall socket is in the primary coil of the transformer?

Answer #1

An ideal step-down transformer has a primary coil of 370 turns
and a secondary coil of 25 turns. Its primary coil is plugged into
an outlet with 115 V(AC), from which it draws an rms current of
0.69 A.
What is the voltage in the secondary coil?
Calculate the rms current in the secondary coil.
Assuming that the transformer secondary is driving a resistive
load, calculate the average power dissipated in the resistor.

a) An ideal step-down transformer has a primary coil of 400
turns and a secondary coil of 14 turns. Its primary coil is plugged
into an outlet with 240 V(AC), from which it draws an rms current
of 0.35 A. What is the voltage in the secondary coil?
b) Calculate the rms current in the secondary coil.
c) Assuming that the transformer secondary is driving a
resistive load, calculate the average power dissipated in the
resistor.

An ideal transformer has 6,000 windings in its primary coil and
10,000 windings in its secondary coil. The primary coil is
connected to an RMS voltage of 480 volts. The secondary coil is
connected to a single 8,000 Ω resistor. What is the current through
the primary coil?

48. A transformer is used to supply a 12-V model train with
power from a 110-V wall plug. The train operates at
50Wofpower.(a)What is the rms current in the secondary coil of the
transformer? (b) What is the rms current in the primary
coil?(c)What is the ratio of the number of primary to secondary
turns? (d) What is the resistance of the train? (e) What is the
resistance seen by the 110-V source?

The primary coil of a transformer has N1 = 340 turns, and the
secondary coil has N2 = 2 190 turns. If the input voltage across
the primary coil is Δv(t) = 170 cos ωt, where Δv is in volts and t
is in seconds, what rms voltage is developed across the secondary
coil?

An AC adapter for a telephone answering machine uses a
transformer to reduce the line voltage of 120 V to a voltage of
4.00 V. The RMS current delivered to the answering machine is 350
mA. If the primary (input) coil of the transformer has 720 turns,
then how many turns are there on the secondary (output) coil?
What is the power drawn from the electric outlet, if the
transformer is assumed to be ideal?
What is the power drawn...

An AC adapter for a telephone answering machine uses a
transformer to reduce the line voltage of 120 V to a voltage of
4.00 V. The RMS current delivered to the answering machine is 660
mA. If the primary (input) coil of the transformer has 600 turns,
then how many turns are there on the secondary (output) coil?
What is the power drawn from the electric outlet, if the
transformer is assumed to be ideal?
What is the power drawn...

An AC adapter for a telephone answering machine uses a
transformer to reduce the line voltage of 120 V to a voltage of
5.00 V. The RMS current delivered to the answering machine is 470
mA. If the primary (input) coil of the transformer has 600 turns,
then how many turns are there on the secondary (output) coil?
What is the power drawn from the electric outlet, if the
transformer is assumed to be ideal?
What is the power drawn...

4 pts each
An ideal transformer within a phone charger takes 120 V from the
wall and converts it into 5 V to the phone. The number of primary
turns must be ? times more than the number of
secondary turns .
(Round your answer to the nearest whole number, do not put any
decimals - so for example 1 and that's it.)
If the phone can handle at most 2.4 A, then the current from the
wall must be ...

QUESTION 4
A transformer has 394 turns on the primary coil and 2,382 turns
on the secondary coil. The RMS voltage on the primary is 120.0
volts, and the power delivered to the transformer is 33.0 watts.
What is the RMS current (milliamps) output from the secondary coil?
(State answer in milliamps with 1 digit right of decimal.)
QUESTION 5
Consider a series RLC circuit with a resistor R = 51.0 Ω, an
inductor L = 2.28 mH, a capacitor...

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