SMT SULOCHANADEVI SINGHANIA SCHOOL CLASS: 10 SUBJECT: PHYSICS WORKSHEET TOPIC: THERMIONIC EMISSION Q1.Which of the radioactive radiations a) can cause severe genetical disorders? b) are deflected by an electric field? c) have the maximum ionising power? d) have the maximum penetration power? e) are negatively charged? f) travel with the speed of light? Q2.A radioactive nucleus undergoes a series of decays according to the sequence A emits to form B which emits an to form C which in turn emits to form X. If mass no. and atomic no. of X are 172 and 69 respectively, what is the mass no. and atomic no. of A ? Q3. What is meant by nuclear waste? Q4. A certain nucleus D has mass no. 14 and atomic no. 6.It changes to E with mass no. 14 and atomic no. 8 after loss of few particles. Name the particles and represent this change in the form of an equation. Q5. What change will take place in the mass no. and atomic no. of a nucleus if it emits radiation? Q6.In a CRT why is a) filament made of tungsten? b) cathode plate coated with oxide of barium ? c) thick glass screen coated with barium platinocyanide? Q7.F is the filament and G is the anode in a cathode ray tube. A 6V and 1000V DC sources are available , which of the two should be connected to F and G respectively and why? Q8. Write 1 similarity and 1 difference between and cathode rays. Q9. Explain why alpha and beta rays are deflected by magnetic field but gamma rays are not. Q10.State 2 conditions for electrons to be emitted from a cold cathode in a discharge tube.
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