F.Sc ICS Notes: Physics XII: Chapter 19 Dawn of Modern Physics Numerical Problems

F.Sc ICS Notes: Physics XII: Chapter 19 Dawn of Modern Physics Numerical Problems 2nd Year Physics Notes Online Taleem Ilmi Hub

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Numerical Problem 19.1: A particle called the pion lives on the average only about 2.6 * 10(-8)s when at rest in the laboratory. It then changes to another form. How long would such a particle live when shooting through the space at 0.95c?

Numerical Problem 19.2: What is the mass of a 70kg man in a space rocket traveling at 0.8c from us as measured from Earth?

Numerical Problem 19.3: Find the energy of photon in

(a) Radiowave of wavelength 100m

(b) Green light of wavelength 550nm

(c) X-ray with wavelength 0.2nm.

Numerical Problem 19.4: Yellow light 577nm wavelength is incident on a cesium surface. The stopping voltage is found to be 0.25 V. Find

(a) the maximum K.E. of the photoelectrons

(b) the work function of cesium.

Numerical Problem 19.5: X-rays of wavelength 22pm are scattered from a carbon target. The scattered radiation being viewed at 85 degree to the incident beam. What is Compton shift?

Numerical Problem 19.6: A 90 KeV X-ray photon is fired at a carbon target and Compton scattering occurs. Find the wavelength of the incident photon and the wavelength of the scattered photon for scattering angle of (a) 30 (b) 60.

Numerical Problem 19.7: What is the maximum wavelength of the two photons produced when a positron annihilates an electron? The rest mass energy of each is 0.51 MeV.

Numerical Problem 19.8: Calculate the wavelength of

(a) a 140 g ball moving at 40 m/s

(b) a proton moving at the same speed

(c) an electron moving at the same speed.

Numerical Problem 19.9: What is the de Broglie wavelength of an electron whose kinetic energy is 120 eV?

Numerical Problem 19.10: An electron is placed in a box about the size of an atom that is about 1 * 10(-10)m. What is the velocity of the electron?

Written by: Asad Hussain