Every lens have two focal points each focal point is present on the either side of the lens. In lenses when light comes from the infinite it passes through the focal point it is true for both converging as well as diverging lens. In mirror there is only one focal point as it one face is covered but in lens light can pass through side of the lens so it has two focal point

4 0

4 years ago

A 21 kg chair initially at rest on a horizontal floor requires a 175 N horizontal force to set it in motion. Once the chair is i

Alika [10]

Answer: $\mu =0.85$

Explanation:

Given

mass of chair m=21 kg

Force required to set chair in motion is 175 N

Once the chair is in motion 137 N is require to move it with constant velocity

i.e. 175 N is the amount of force needed to just overcome static friction and 137 is the kinetic friction force

thus

$f_s(static\ friction)=\mu \cdot N$

where $\mu$ is the coefficient of static friction and N is Normal reaction

$N=mg$

$f_s=\mu mg$

$\mu mg=175$

$\mu =\frac{175}{21\times 9.8}$

$\mu =0.85$

8 0

3 years ago

Complete the electron-pushing mechanism for the e1 reaction when 2-methylbutan-2-ol is treated with 20% sulfuric acid.

Sav [38]

E1 reaction works in the mechanism that the removal of an HX substituent results in the formation of a double bond. The E1 reaction for 2-methylbutan-2-ol is shown in the figure. This reaction is called acid-catalyzed dehydration of a tertiary alcohol.

The mechanism works in three major steps:
1. The OH group of the main reactant is hydrated by H2SO4 so it becomes H2O.
2. The H2O leaves taking electrons with it. This results to a carbocation intermediate on the carbon atom where it was attached.
3. Another H2O protonates the beta carbon. This is the carbon atom next to the carbocation. It will donate its electrons to the neighboring C-C bond, as indicated by the arrow. The carbons are rehybridized from sp3 to sp2, which is a pi bond. As a result, a double bond forms.

The product is 2-methyl-2-butene.

6 0

4 years ago

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