- #1

mikejones2000

- 18

- 0

## Homework Statement

A 58.0 resistor, a 3.00 µF capacitor, and a 0.400 H inductor are connected in series to a 77.0 V (rms), 60.0 Hz source.

(a) Find the voltage drop across the LC combination.

(b) Find the voltage drop across the RC combination.

## Homework Equations

For RC-> Z=sqr(R^2+Xc^2), Vmax=ImaxZ, For LC-> Z=sqr(R^2+(Xl-Xc)^2), I=V/R, Vmax=V(sqr(2)).

## The Attempt at a Solution

I calculated Imax first and then found each different Z. I then put the values into Vmax=ImaxZ.

## Homework Statement

An AC adapter for a telephone-answering unit uses a transformer to reduce the line voltage of 120 V (rms) to a voltage of 9.5 V. The rms current delivered to the answering system is 390 mA.

(a) If the primary (input) coil in the transformer in the adapter has 240 turns, how many turns are there on the secondary (output) coil?

(b) What is the rms power delivered to the transformer? Assume an ideal transformer.

## Homework Equations

Vc=(N2/N1)V1, Pav=IrmsVr

## The Attempt at a Solution

I know how to get the first part of this question but the second eludes me. I tried using 120V for Vr and also 120(sqr(2)) considering the transformer is ideal.

## Homework Statement

Suppose you wish to use a transformer as an impedance-matching device between an audio amplifier that has an output impedance of 6.8 k and a speaker that has an input impedance of 6.5 . What should be the ratio of primary to secondary turns on the transformer?

## Homework Equations

I could not find any equations relating impedance and transformers in my text but I found one online->Z1/Z2=(N1/N2)^2

## The Attempt at a Solution

Plug'chugged and got it wrong. :(

## Homework Statement

The intensity of solar radiation at the top of Earth's atmosphere is 1340 W/m3. Assuming that 60% of the incoming solar energy reaches Earth's surface and assuming that you absorb 50% of the incident energy, make an order-of-magnitude estimate of the amount of solar energy you absorb in a 60 minute sunbath. (Assume that you occupy a 1.7 m by 0.3 m area of beach blanket and that the sun's angle of elevation is 60°.)

## Homework Equations

## The Attempt at a Solution

I am rather clueless at where to begin with this one. I understand that the energy will be reduced by .6 and then by .5 but I am pretty stumped.