Some conceptual questions about physics. 1. If an electric charge is shaken up a

Question

Some conceptual questions about physics.

1. If an electric charge is shaken up and down

a) sound is emitted

b) visible light is absorbed

c) a magnetic field is created

d) electrons are excited

2. A dentist has an illumination light that uses a concave mirror to focus a bright light onto a patient's mouth. Assume that the mirror is positioned 0.50m from the patient, and that it has a focal length of 14cm. How far should the lamp be placed from the mirror?

a) 0.11m b) 0.21m c) 0.42m d) 1.21m

3. A particle in a 453 m-long linear accelerator is moving at 0.875c. How long does the accelerator appear to the paricle
a) 104m b) 219m c) 589m d) 936m

Explanation / Answer

1) Answer [C], when a charge is shaken up n down, its a periodic motion so it has an acceleration & an accelerated charged particle creates a magnetic field!

2) 1/f = (1/d1) - (1/d2)

1/d1 = (1/0.14) + (1/0.5)

1/d1 = 9.143

d1 = 0.11 m (Option A)

3) Use this relativity equation:
L = Lp*sqrt(1-v^2/c^2)
plug numbers into equation.
L = 453*sqrt(1-0.875^2)

   = 219.3m (option B)

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