Dual Nature Of Light Question 100
Question: An X-ray tube is operating at 50 kV and 20 mA. The target material of the tube has a mass of 1.0 kg and specific heat 495 J kg-1 $ ^{o}{{C}^{-1}} $ . One percent of the supplied electric power is converted into X-rays and the entire remaining energy goes into heating the target. Then [IIT 1995]
Options:
A) A suitable target material must have a high melting temperature
B) A suitable target material must have low thermal conductivity
C) The average rate of rise of temperature of target would be 2 °C/s
D) The minimum wavelength of the X-rays emitted is about $ 0.25\times {{10}^{-10}},m $
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Answer:
Correct Answer: C
Solution:
$ P=VI=50\times 10^{3}\times 20\times {{10}^{-3}}=1000W $ Power converted into heat = 990 W $ ms\Delta T=990,\Rightarrow \Delta T=2^{o}C/\sec $ Now $ \frac{hc}{{\lambda_{\min }}}=eV $
$ \Rightarrow ,{\lambda_{\min }}=\frac{hc}{eV}=0.248\times {{10}^{-10}}m $
BETA
