modern physics

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Across
  1. 4. the target in a Coolidge tube
  2. 9. the kind on waves that x ray is
  3. 11. combination of heater cathode and anode
  4. 13. study hearts action
Down
  1. 1. minimum energy required for an electron to be emitted
  2. 2. a metal with low work function
  3. 3. cause this phenomenon in ZnS
  4. 5. the scientist who explains photo electric effect
  5. 6. device to convert light to electrical energy
  6. 7. discovered in the year 1895
  7. 8. short wavelength x-rays
  8. 10. another name for critical value
  9. 12. intensity controlled by changing this