# The amplitude of the electric field is 0.9 V/m 42 km from a radio transmitter. What is the total power emitted by the transmitter, if one assumes that the radiation is emitted isotropically (uniformly in all directions)? The impedence of free space is 377 Ω . Answer in units of W.

The power is found to be P = 14250600 W

Explanation:

First we find the voltage or potential difference at the position:

Voltage = Amplitude of Field x Distance

Voltage = V = (0.9 V/m)(42000 m)

V = 37800 volts

Now, we know the formula of electric power is:

Power = Voltage x Current

P = V I

but, from Ohm's Law:

V = I R

I = V/R

Therefore,

P = V²/R

Resistance = real part of impedence = 377 Ω

Therefore,

P = (37800 V)(377 Ω)

P = 14250600 W

## Related Questions

At a speed of 60 mph, how far does your car travel in 3 seconds

One of the many random useless factoids that I carry around
in my head is the factoid that 60 miles per hour is equivalent
to exactly 88 feet per second.

So in three seconds at that speed, you would cover exactly

(3 x 88) = 264 feet.

An 80.0-kg object is falling and experiences a drag force due to air resistance. The magnitude of this drag force depends on its speed, v, and obeys the equation Fdrag=(12.0N⋅s/m)v+(4.00N⋅s2/m2)v2. What is the terminal speed of this object?

Terminal velocity of object = 12.58 m/s

Explanation:

We know that the terminal velocity is attained when drag force and gravitational force are of the same magnitude.

Gravitational force = mg = 80 * 9.8 = 784 N

Drag force =

Equating both, we have

So v = 12.58 m/s or v = -15.58 m/s ( not possible)

So terminal velocity of object = 12.58 m/s

A stone was dropped off a cliff and hit the ground with a speed of 96 ft/s. What is the height of the cliff? (Use 32 ft/s2 for the acceleration due to gravity.)

The initial velocity of the stone is 0 ft/s. Given the initial velocity (Vi), final velocity (Vf), and acceleration due to gravity (g), the distance may be calculated through the equation,
d = ((Vf)² - (Vi)²) / 2g
Substituting the known values,
d = ((96 ft/s)² - 0))/ (2x32.2)
The value of d is 143.10 ft.

A certain helium-neon laser pointer, emitting light with a wavelength of 632 nm, has a beam with an intensity of 825 W/m2 and a diameter of 2.80 mm. How many photons are emitted by the laser pointer every second?

Explanation:

Energy of each photon is given as

here we will have

now we will have

now let say there is N number of photons per second

so power due to photons is

now intensity is given as power received per unit area

so we have