Physics tutorial #20
1. Determine the minimum height of a vertical flat mirror in which a person 1.75m in height can see
his or her full image. (A ray diagram would be helpful.)
2. Calculate the image position and magnification for an object placed 1 m in front of (a) convex
and (b) concave mirror, both of focal length 70 cm. Use ray diagrams to locate image positions
corresponding to the object positions in (a) and (b).
3. A concave spherical mirror has focal length equal to 50 cm.
(a) Plot the image position as a function of the object position.
(b) Prepare ray diagrams for objects placed in a distance of 25 cm and 75 cm from the mirror and
mark positions of their images on the plot prepared in (a).
4. A concave mirror has a radius of curvature of 60 cm. Calculate the image position and magnification
of an object placed in front of the mirror at distances of (a) 90 cm and (b) 20 cm. (c) Draw ray
diagrams to obtain the image in each case.
5. Calculate the image position and magnification for an object placed (a) 20 cm and (b) 60 cm in
front of a convex mirror of focal length -40 cm. (c) Use ray diagrams to locate image positions
corresponding to the object positions in (a) and (b).
6. A radio station operating at a frequency of 1500 kHz (near the top end of the AM broadcast band)
has two identical dipole antennas spaced 400 m apart, oscillating in phase. At distances much greater
than 400 m, in what directions is the intensity greatest in the resulting radiation pattern?
7. A water film (n = 1.33) in air is 320 nm thick. If it is illuminated with white light at normal
incidence, what colour will it appear to be reflected light?
8. 633-nm laser light passes through a narrow slit and creates the diffraction pattern on a screen 6 m
away. The distance on the screen between the centres of the first minima outside the central bright
fringe is 32 mm. How wide is the slit?
Nivas Babu Selvaraj, Maciej Woloszyn
http://fatcat.ftj.agh.edu.pl/~woloszyn/phys/