Explanation:
We need to calculate the speed of light in each materials
(I). Gallium phosphide,
The index of refraction of Gallium phosphide is 3.50
Using formula of speed of light
....(I)
Where,
= index of refraction
c = speed of light
Put the value into the formula


(II) Carbon disulfide,
The index of refraction of Gallium phosphide is 1.63
Put the value in the equation (I)


(III). Benzene,
The index of refraction of Gallium phosphide is 1.50
Put the value in the equation (I)


Hence, This is the required solution.
Answer:
Average velocity

Average speed,

Explanation:
(a)Average velocity
We have to find the average velocity. We know that velocity is defined as the rate of change of displacement with respect to time.
To find the average velocity we have to find the total displacement.
since displacement along east direction is 50m
and displacement along west=40m
so total displacement,

total time,

therefore, average velocity

(b)Average Speed:
Average speed is defined as the ratio of total distance to the total time
it means
Average speed= total distance/total time
here total distance,

and total time,

therefore,
Average speed,

Explanation:
Area of ring 
Charge of on ring 
Charge on disk

![\begin{aligned}d v &=\frac{k d q}{\sqrt{x^{2}+a^{2}}} \\&=2 \pi-k \frac{a d a}{\sqrt{x^{2}+a^{2}}} \\v(1) &=2 \pi c k \int_{0}^{R} \frac{a d a}{\sqrt{x^{2}+a^{2}}} \cdot_{2 \varepsilon_{0}}^{2} R \\&=2 \pi \sigma k[\sqrt{x^{2}+a^{2}}]_{0}^{2} \\&=\frac{2 \pi \sigma}{4 \pi \varepsilon_{0}}[\sqrt{z^{2}+R^{2}}-(21)] \\&=\frac{\sigma}{2}(\sqrt{2^{2}+R^{2}}-2)\end{aligned}](https://tex.z-dn.net/?f=%5Cbegin%7Baligned%7Dd%20v%20%26%3D%5Cfrac%7Bk%20d%20q%7D%7B%5Csqrt%7Bx%5E%7B2%7D%2Ba%5E%7B2%7D%7D%7D%20%5C%5C%26%3D2%20%5Cpi-k%20%5Cfrac%7Ba%20d%20a%7D%7B%5Csqrt%7Bx%5E%7B2%7D%2Ba%5E%7B2%7D%7D%7D%20%5C%5Cv%281%29%20%26%3D2%20%5Cpi%20c%20k%20%5Cint_%7B0%7D%5E%7BR%7D%20%5Cfrac%7Ba%20d%20a%7D%7B%5Csqrt%7Bx%5E%7B2%7D%2Ba%5E%7B2%7D%7D%7D%20%5Ccdot_%7B2%20%5Cvarepsilon_%7B0%7D%7D%5E%7B2%7D%20R%20%5C%5C%26%3D2%20%5Cpi%20%5Csigma%20k%5B%5Csqrt%7Bx%5E%7B2%7D%2Ba%5E%7B2%7D%7D%5D_%7B0%7D%5E%7B2%7D%20%5C%5C%26%3D%5Cfrac%7B2%20%5Cpi%20%5Csigma%7D%7B4%20%5Cpi%20%5Cvarepsilon_%7B0%7D%7D%5B%5Csqrt%7Bz%5E%7B2%7D%2BR%5E%7B2%7D%7D-%2821%29%5D%20%5C%5C%26%3D%5Cfrac%7B%5Csigma%7D%7B2%7D%28%5Csqrt%7B2%5E%7B2%7D%2BR%5E%7B2%7D%7D-2%29%5Cend%7Baligned%7D)
Note: Refer the image attached
Answer:
0.85 A
Explanation:
the effective current is 0.85 A