Bukhovtsev-et-al-Problems-in-Elementary-Physics

108
....-------------
PROBLEJ\\S
Fig. 182
Fig. 183
~~------
~
Fig. 184
526. Why are the anode and the anticathode of an X-ray
tube connected by a wire (see Problem 525)? What will occur
if the anticathode is isolated?
527. Figure 181 shows a Geiger-Muller counter of elementary
particles. A high voltage is. produced between the housing of
tube A and a thin wire ab that is only slightly smaller than
the critical voltage necessary to ignite the charge.
When a fast charged particle enters the counter, the molecules
of the gas are ionized and a discharge begins. The flow of
current through the circuit is accompanied by a drop of voltage
across the large resistance R. This voltage drop is recorded
after amplification by corresponding instruments.
For the counter to answer its purpose, the discharge caused
by the particle should be quickly extinguished. What extinguishes
the discharge in the circuit in Fig. 181?
528. A capacitor with a capacitance C = 8 ern and a distance
between the plates of
d = 3 mm is connected to a high-voltage
source through a resistance of R = l03Q (Fig. 182).
The air in the space between the plates of the capacitor is
ionized by X-rays so that n = 10· ionic pairs form in one cubic
centimetre per second. The charge of each ion is equal to that
of an electron.
Find the vol tage drop across the resistance R assuming that
all the ions reach the plates before they recombine.
529. What will occur to a burning electric arc if the negative
carbon is intensively cooled? What will. occur if the positive
carbon is cooled?
530. Why is an electric iron with a thermocontroller used
only with alternating current?
531. What energy in ergs will an electron acquire after passing
through a potential difference of 1 V in a vacuum? (In atomic
physics this energy is taken as the unit "electron-volt")