Help please :) 15 points.

Even in the most advanced circuits, we cannot oscillate electrons back and forth at that rate through wires. But we can oscillat

den301095 [7]

Answer:

the oscillations of the electrons must be in the 10⁸ Hz = 100 MHz range

Explanation:

The speed of a wave of radio, television, light, heat, all are manifestations of electromagnetic waves that are oscillations of electric and magnetic fields that support each other, the speed of all these waves is the same and the vacuum is equal to c = 3 108 m / s

All waves have a relationship between the speed of the wave, its frequency and wavelength

c = λ f

f = c /λ

for this case lam = 1 m

f = 3 10⁸/1

f = 3 10⁸ Hz

the oscillations of the electrons must be in the MHz range

It should be clarified that the speed of light in air is a little lower

n = c / v

v = c / n

the refractive index of vacuum is n = 1 and the refractive index of air is n = 1.000002

5 0

2 years ago

A van is traveling on a road at a speed of 55 km/h. A girl sitting near the driver of the van throws a paper airplane to a boy a

aivan3 [116]

<span>A van is traveling on a road at a speed of 55 km/h relative to a
stationary observer on the side of the road. A girl sitting near the
driver of the van throws a paper airplane to a boy at the back of the
van with a speed of 2 km/h relative to the girl, the boy, and the van.

The speed of the paper airplane, relative to the same stationary observer
on the side of the road, is (55 - 2) = 53 km/h. No rounding is necessary.</span>

5 0

3 years ago

Read 2 more answers

A 80 W light bulb (normally run at 120 V) is attached to a transformer. The voltage source in the transformer is 65 V and Np = 3

Marina CMI [18]

67.8 turns needed by the secondary coil to run the bulb.

<u>Explanation</u>:

We know that,

$\text { Electric power }(p)=\frac{V^{2}}{R}$

$\text { Hence, } \frac{P_{1}}{P_{2}}=\frac{V_{1}^{2} / R}{V_{2}^{2} / R}$

$\frac{P_{1}}{P_{2}}=\frac{V_{1}^{2}}{V_{2}^{2}}$

For calculating number of turns

$\frac{N_{P}}{N_{S}}=\frac{V_{P}}{V_{S}}$

Given that,

$80 \mathrm{W}\left(P_{1}\right) \text { bulb with voltage } 120 \mathrm{V}\left(V_{1}\right) \text { is connected to a transformer. }$

$\text { The source voltage of a transformer is }\left(V_{P}\right) \text { is } 65 \mathrm{V}$

$\text { The number of turns in primary winding of transformer is }\left(N_{P}\right) \text { is } 30 .$

We need to find the number of turns in the secondary winding $\left(N_{S}\right)$ to run the bulb at 120W $\left(P_{2}\right)$

Firstly find the secondary voltage in the transformer use, $\frac{P_{1}}{P_{2}}=\frac{V_{1}^{2}}{V_{2}^{2}}$

$\frac{80}{120}=\frac{120^{2}}{V_{2}^{2}}$

$V_{2}^{2}=\frac{120^{2} \times 120}{80}$

$V_{2}^{2}=\frac{1728000}{80}$

$V_{2}^{2}=21600$

$V_{2}=\sqrt{21600}$

$V_{2}=146.9 \mathrm{V}=V_{S}$

Now, finding the number of turns in secondary coil. Use, $\frac{N_{P}}{N_{S}}=\frac{V_{P}}{V_{S}}$

$\frac{30}{N_{S}}=\frac{65}{146.9}$

$N_{S}=\frac{30 \times 146.9}{65}$

$N_{S}=\frac{4407}{65}$ $N_{S}=67.8$

The number of turns in the secondary winding are 67.8 turns.

6 0

2 years ago

The coefficient of linear expansion of steel is 12 × 10-6 K-1 . What is the change in length of a 25-m steel bridge span when it

Westkost [7]

Answer:

0.012-m

Explanation:

∆L = α × Lo × (T-To)

α is the coefficient of linear expansion = 12 × 10-6 K-1

Lo = Initial length = 25-m

∆L = Change in length

(T-To) = 40 K

∆L = 12 × 10-6 × 25 × 40

∆L = 0.012-m

4 0

3 years ago

What were two arguments or lines of evidence in support of the geocentric model?

Inessa05 [86]

Answer:

Two arguments or lines of evidence in support of the geocentric model are:

Geocentric model: This model describe that the earth is in the center of the universe and all the planets. Moon and the sun are revolved around the earth. This model explained the predominant description.

Heliocentric model: In this model the earth and the sun are consider moving and the sun are in the center of the solar system. And the sun is at the center position where all the planets are revolving around it, being dissimilar to the geocentric model.

7 0

2 years ago