Question 3
A. In the experiment with a diffraction grating, a first order diffraction image is observed
at an angular displacement of 18°44'. At what angle, in degrees and minutes, would
you expect the second order image to be found?
[3]
B. A grating ruled with 598 lines per mm, mounted on a spectrometer table, is illuminated
with light from a mercury source. The following Vernier scale readings were obtained
for one of the blue lines in the second order spectrum, with the telescope first to the left
and then to the right of the straight-through beam.
Left Vernier 1 Vernier 2
Right 343°33? 163°33?
?=20 46°19? 226°22?
Calculate the wavelength of the line.
[5]
Question 4
A. You are provided with a slide-wire AB (mounted with connecting strips on a frame as
shown below), a galvanometer, a 2.0V cell, a standard resistance of value 5.0 ?, and
a piece of manganin resistance wire 100 mm long and 1 mm² in cross-sectional area.
A
B
Using clear labels, show how you would connect this equipment in order to measure
the resistance of the manganin wire, and write down the balance condition for your
circuit.
[6]
