One observer stands on a train moving at a constant speed, and one observer stands at rest on the ground. The person on the train stands at the back of the car and turns on a flashlight; the light travels to the front of the car, bounces off a mirror, and returns to the back of the car (assume the light is traveling in a vacuum). The observer on the ground measures the time it takes for the light to take this path and knowing the length of the car, calculates the speed of light. What value does she obtain?

a.)greater than c

b.) equal to c

c.) less than c

d.) value cannot be calculated without knowing the speed of the train

Option D.

Value cannot be calculated without knowing the speed of the train

Explanation:

The speed of the beam can only be calculated accurately when the speed of the train is put into consideration. Based of the theory of relativity, the observer is on the ground, and the train is moving with the beam of light inside it. This causes a variation in the reference frames when making judgements of the speed of the beam. The speed of the beam will be more accurate if the observer is moving at the same sped of the train, or the train is stationary.

To get the correct answer, we have to subtract the speed of the train from the speed calculated.

i agree kid

explanation:

a

electromagnetic shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials. shielding is typically applied to enclosures to isolate electrical devices from their surroundings, and to cables to isolate wires from the environment through which the cable runs. electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as rf shielding.

the shielding can reduce the coupling of radio waves, electromagnetic fields and electrostatic fields. a conductive enclosure used to block electrostatic fields is also known as a faraday cage. the amount of reduction depends very much upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of apertures in a shield to an incident electromagnetic

from wikipedia