The alpha line in the Balmer series is the transition from n=3 to n=2 and with the wavelength of λ=656 nm = 6.56*10^-7 m. To get the frequency we need the formula: v=λ*f where v is the speed of light, λ is the wavelength and f is the frequency, or c=λ*f. c=3*10^8 m/s. To get the frequency: f=c/λ. Now we input the numbers: f=(3*10^8)/(6.56*10^-7)=4.57*10^14 Hz. So the frequency of the light from alpha line is f= 4.57*10^14 Hz.
If Earth was twice as far from the sun, the force of gravity attracting the Earth to the sun would be only one-quarter as strong. The correct answer will be C.
Answer:
x=22.57 m
Explanation:
Given that
35 m in W of S
angle = 40 degrees
25 m in east
From the diagram
The angle

From the triangle OAB


x=22.57 m
Therefore the answer of the above problem will be 22.57 m
Answer:
At light intensity I = 3, is P a maximum
Explanation:
Given:

now differentiating the above equation with respect to Intensity 'I' we get

or

or

or

Now for the maxima 
thus,

or

or

or

or
I = 3
thus, <u>for the value of intensity I = 3, the P is maximum</u>
at I = 3

or

or

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