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3 years ago

Electromagnetic waves with wavelength between about 1 cm and 20 cm are called??

Physics

1 answer:

kodGreya [7K]3 years ago

8 0

I believe the answer is Microwaves (just to clarify, not the oven). They're widely used for communications.

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Waves that move matter back and forth are called a.transverse waves b.longitudinal wave c. Medium wave

Travka [436]

Waves that move matter back and forth are called a.transverse waves b.longitudinal wave c. Medium wave

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3 years ago

Read 2 more answers

I Cghggbbbtffhhtrf bvbbjkko

adelina 88 [10]

kzkjskßkjxjdkxkdksk

Explanation:

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3 years ago

Francium-223 has a half-life of 22 minutes. A Geiger counter gives a reading of 58 counts per minute (cpm) from a sample of fran

polet [3.4K]

Answer:

29 counts per minute (29 cpm)

Explanation:

The half-life of a radioactive isotope is the time needed for the activity of the sample to halve.The half-life of Francium-223 is exactly 22 minutes: this means that its activity after 22 minutes becomes exactly half of its initial value. Since the initial activity of this sample of francium-223 was 58 cpm, the activity after 22 minutes will be

$A=\frac{58 cpm}{2}=29 cpm$

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3 years ago

When you hear an ambulance siren, it alternates between high and low tones, depending on the frequency of sound waves. this is c

dangina [55]

Frequency of a sound wave is called the pitch. Higher frequencies have a higher pitch and lower frequencies have the opposite. When an ambulance travels by a listener, the frequencies are oscillating rapidly and causing the shrill, loud sounds that emanate from the sirens.

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4 years ago

Recall from Chapter 1 that a watt is a unit of en- ergy per unit time, and one watt (W) is equal to one joule per second ( J·s–1

harkovskaia [24]

Answer:

Explanation:

The energy of a photon is given by the equation $E_p=h f$ , where h is the Planck constant and f the frequency of the photon. Thus, N photons of frequency f will give an energy of $E_N=N h f$ .

We also know that frequency and wavelength are related by $f=\frac{c}{\lambda}$ , so we have $E_N=\frac{N h c}{\lambda}$ , where c is the speed of light.

We will want the number of photons, so we can write

$N=\frac{\lambda E_N}{h c}$

We need to know then how much energy do we have to calculate N. The equation of power is $P=E/t$ , so for the power we have and considering 1 second we can calculate the total energy, and then only consider the 4% of it which will produce light, or better said, the N photons, which means it will be $E_N$ .

Putting this paragraph in equations:

$E_N=(\frac{4}{100})E=0.04Pt=(0.04)(100W)(1s)=4J$ .

And then we can substitute everything in our equation for number of photons, in S.I. and getting the values of constants from tables:

$N=\frac{\lambda E_N}{h c}=\frac{(520 \times10^{-9}m) (4J)}{(6.626\times10^{-34}Js) (299792458m/s)}=1.047 \times10^{19}$

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3 years ago