PHYS 2425- Exam 4

1. The magnetic field equation for an electromagnetic wave is

Find an equation for the electric field and determine the direction which the wave travels. (20 points)

2. Sarah is using a device which radiates electromagnetic wave uniformly in all direction. The information on this device specifies that the amplitude of electric field is 3.50 N/C at the distance of 10 m from source. What would be the amplitude of electric field for this device at the distance of 20 m? (20 points)

3. The picture shows the path of ray when traveling from an unknown material to water and then air. (a)Find the index of refraction for the unknown material. (b) Find the angle between the normal and ray in air. (20 points)

4. Use the information below for a concave mirror and (a) find the distance of the image to the mirror. (b) determine if it is real or virtual, (c) Draw a ray diagram, (d) Find the magnification. (20 points)

Radius of curvature= 32cm

Distance of the object to the mirror= 12 cm

5. Use the information below for a converging lens and answer the questions. (20 points)

-Focal length=12 cm

-Image is virtual

-Distance of the image to the lens is 17 cm

-The image is on the right side of the lens

-Image is 8 mm tall

(a)What is the distance of the object to the lens?

(b)What is the size of object?

(c)Is the image upright or inverted?