Answer:
Explanation:
A )
speed of swimming in still water is given by the expression
distance / time
= 50 / 25
= 2 m /s
In lane 1 , 1.2 cm/s current is flowing in the direction that the swimmers are going so swimmers will cover distance at the rate of 2 + 1.2 = 3.2 m /s.
time to cover distance of 50 m in lane 1
= distance / speed
= 50 / 3.2 = 15.625 s
In lane 8 , 1.2 cm/s current is flowing against the direction that the swimmers are going so swimmers will cover distance at the rate of 2 - 1.2 = .8 m /s.
time to cover distance of 50 m in lane 1
= distance / speed
= 50 / .8 = 62.5 s
We anticipate a constant Poynting vector of magnitude since the hot resistor will be emitting heat and none of the electric or magnetic fields will change over time.
S = P/A
= I2R/ 2πrL
= 332 kW/m2
Always pointing away from the wire, this Poynting vector.
<h3>What is the Poynting vector?</h3>
Describes the size and direction of the energy flow in electromagnetic waves using a Poynting vector. It bears the name of the 1884 invention of English physicist John Henry Poynting. It stands for the electromagnetic field's directional energy flux or power flow. The Poynting vector is significant in a static electromagnetic field because it determines the direction of energy flow in an electromagnetic field. This vector represents the radiation pressure of an electromagnetic wave and points in its direction of propagation.
To learn more about Poynting vector, visit:
<u>brainly.com/question/17330899</u>
#SPJ4
Answer:
they cross over one another between charge.
Answer:potential difference is more or less like voltage. Using ohms, V=IR
Where V is Voltage
I is Current =0.4A
R is Resistance=20ohms
V=0.4*20
V=8V
Hence the potential difference will be 8V.
ii) V=0.4*30
V=12V
Explanation:
The voltage of potential difference is directly proportional to the current and the resistance. So if one increase or decrease, it will have impact on the other.
From the calculations, when the resistance increase, the voltage will increase to appreciate the change.
Answer:
red shift, indicating that the universe is expanding
Explanation:
Doppler effect occurs when a source of a wave (e.g. light, or sound waves) moves relative to an observer; as a result of this relative motion, the wavelength of the wave appears lengthened/shortened to the observer. Two situations can occur:
- The source of the wave is moving towards the observer - in this case, the wavelength of the wave becomes shorter. If the wave is visible light, such as the light emitted by distant galaxies, this means that the wavelength of the light shifts towards the blue-end of the spectrum (blue-shift)
- The source of the wave is moving away from the observer - in this case, the wavelength of the wave becomes longer. If the wave is visible light, such as the light emitted by distant galaxies, this means that the wavelength of the light shifts towards the red-end of the spectrum (red-shift)
In our universe, we observe a red-shift for all the distant galaxies: this means that these galaxies are moving away from us, so this is an indication that the universe is expanding.
