Answer:False.
Explanation: HIV is a viruse that only shows symptoms after a few weeks. in Fact HIV does not show any physical symptoms. So, no you can not tell if someone has or is been infected by HIV by directly looking at them.
Have a Nice Day!!! =)
Answer:
A) 
= 77.6 ⁰C
, B) = 341.6 C
Explanation:
The thermal expansion is given by
ΔL = α L₀ ΔT
The thermal expansion coefficient for polycarbonate varies between 65 and 70 10⁻⁶ ⁰C⁻¹ and for cast iron 12 10⁻⁶ C⁻¹
Let's look for the final temperature that says same shift change
ΔT = ΔL / α L₀
- T₀ = ΔL /α L₀
= T₀ + ΔL / α L₀
Let's calculate for each material
A) Polycarbonate use as thermal expansion coefficient 70 10⁻⁶ C⁻¹
= 23.0 + 0.0268 / (70 10⁻⁶ 7.01)
= 23.0 + 54.6
= 77.6 ⁰C
B) cast iron with thermal expansion coefficient 12 10⁻⁶ C⁻¹
= 23.0 + 0.0268 / (12 10⁻⁶ 7.01)
= 23.0 + 3.1859 10²
= 341.6 C
Answer: (Next time put the Image but I know what u talkin bout)
wave changes its path from its initial direction so this phenomenon is known as Refraction of wave
Explanation:
When wave travels from one medium to other medium the due to change in the speed of the wave propagation it deviates from its initial path.
The deviation of the wave from its initial path is known as refraction of wave
Here we can see that wave incident on medium 1 with some angle with the boundary
Then it enters into other medium and then travels in other direction
So here wave changes its path from its initial direction so this phenomenon is known as Refraction of wave
