Answer:
Inside the film the wavelength will be λ/n
For constructive interference to occur the film must be λf/4 thick where λf is the wavelength of the light in the film - there will be a 180 degree phase shift at the water/film interface since the index of refraction of the film is greater than that of water - and the light has to travel λ/2 inside the film for constructive interference to occur
280 nm / 1.6 * 4 = 700 nm is the greatest wavelength allowed
Note that 700 nm is also the upper wavelength of the visible spectrum
At critical temperature, the resistivity of the superconductor
B. It suddenly drops to zero
Explanation:
Materials can be classified into three different types depending on their resistance:
- Conductors: these materials have generally low resistance and allow electricity to pass through easily. The resistance of a conductor increases linearly with the temperature
- Insulators: these materials do not allow electricity to pass through - so they have very high resistance
- Semi-conductors: these are materials that are insulators are room temperature, however they becomes conductors when heated. Therefore, the resistance of a semiconductor decreases when the temperature increases
- Superconductors: these are special materials that are normally conductors; however, at very low temperatures (we are talking about temperature very near to 0 K), their resistance becomes suddenly zero.
Therefore, the correct answer is:
B. It suddenly drops to zero
Learn more about current and resistance:
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Answer:
A.) 1430 metres
B.) 80 seconds
Explanation:
Given that the train accelerates from rest at 1.1m/s^2 for 20s. The initial velocity U will be:
U = acceleration × time
U = 1.1 × 20 = 22 m/s
It then proceeds at constant speed for 1100 m
Then, time t will be
Time = distance/ velocity
Time = 1100/22
Time = 50 s
before slowing down at 2.2m/s^2 until it stops at the station.
Deceleration = velocity/time
2.2 = 22/t
t = 22/2.2
t = 10s
Using area under the graph, the distance between the two stations will be :
(1/2 × 22 × 20) + 1100 + (1/2 × 22 × 10)
220 + 1100 + 110
1430 m
The time taken between the two stations will be
20 + 50 + 10 = 80 seconds
Well, if i am correct. a substance is:
a particular kind of matter with uniform properties
or...
the real physical matter of which a person or thing consists and which has a tangible, solid presence.
choose which ever you like better:)
