Use the Inverse square law, Intensity (I) of a light is inversely proportional to the square of the distance(d).
I=1/(d*d)
Let Intensity for lamp 1 is L1 distance be D1 so on, L2 D2 for Intensity for lamp 2 and its distance.
L1/L2=(D2*D2)/(D1*D1)
L1/15=(200*200)/(400*400)
L1=15*0.25
L1=3.75 <span>candela</span>
Answer : The de-Broglie wavelength of this electron, 
Explanation :
The formula used for kinetic energy is,
..........(1)
According to de-Broglie, the expression for wavelength is,

or,
...........(2)
Now put the equation (2) in equation (1), we get:
...........(3)
where,
= wavelength = ?
h = Planck's constant = 
m = mass of electron = 
K.E = kinetic energy = 
Now put all the given values in the above formula (3), we get:


conversion used : 
Therefore, the de-Broglie wavelength of this electron, 
According to the principle of continuity, the velocity of a fluid multiplied by the cross-section through which it flows at one point will equal the product of velocity and cross-section at another point.
The principle of continuity, also known as the continuity equation, is the fluid mechanic's principle. Simply put, what flows into a defined volume over a specified period of time minus what flows out of that volume over that specified period of time must accumulate in that volume. The substance in that volume is depleted if the accumulation's sign is negative.
This is so that our eyes, once they start to follow anything, will keep moving in that direction until they come across another thing or object. A line with an arrow at the end of it, for instance, is a great illustration of the continuity concept.
Note that three conditions must be met for a function to be continuous at a point: At that time, the limit must exist.
Learn more about the principle of continuity:
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Answer:
22.658 N
Explanation:
We can consider the Force as a sum of horizontal and vertical force vector components as mentioned in the graph,
Here the θ =25 degrees , F=25
Horizontal force =Fx
cos θ 

Answer:
F = 0.075 N
Explanation:
given,
diameter of ping pong ball = 2.55 cm
average density of the ball = 0.116 g/cm³
Force require to hold the ball completely submerged= ?
Volume of the ball


V = 8.63 cm³
density of water = 1 g/cm³
force required to keep the ball submerged is equal to


F = 7.63 x 9.8 x 10⁻³
F = 0.075 N
Force required to keep the ball inside the water is equal to 0.075 N