Answer:
All statement are correct.
Explanation:
1. Electric field lines are the same thing as electric field vectors, electric field are mathematically vectors quantity. These vectors point in the direction in which a positive test charge would move.
2. Electric field line drawings allow you to determine the approximate direction of the electric field at a point in space. Yes it is correct tangent drawn at any point on these lines gives the direction of electric filed at that point.
3. The number of electric field lines that start or end at a charged particle is proportional to the magnitude of charge on the particle, is a correct statement.
4.The electric field is strongest where the electric field lines are close together, again a correct statement as relative closeness of field lines indicate a stronger strength of electric field.
Hence we can say that all the statement are correct.
E = 300km * 2000J/km = 600000J
The rotational energy is given by:
E = 0.5 * I * ω²
I for a uniform cylinder is given by:
I = 0.5 * m * r²
Resulting equation:
E = 0.25 * m * r² * ω²
Given values:
ω = 430 rev/s = 430 * 2π / s
E = 600000
Solve for r.
Answer:
The diameter of the moon's image is 0.31 cm.
Explanation:
Given that,
Focal length = 34.3 cm
Diameter of the moon 
Mean distance from the earth 
At that distance the object is assumes to be at infinity. hence the image will be formed at a distance equal to focal length
So, the image distance is 34.3 cm.
We need to calculate the diameter of the moon's image
Using formula of magnification




Hence, The diameter of the moon's image is 0.31 cm.
Answer:
Scalar quantity is the Physical quantity expresed only by their magnitude.
Answer:
Repeaters
Explanation:
EMS are communication systems that coordinates emergency medical care among ambulances, 911 (telephone) dispatch centers, and hospital emergency departments. According to my research on EMS systems, I can say that based on the information provided within the question you would need Repeaters. These are a piece of hardware that repeats and extends a signal so that it reaches a greater distance.
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