How does one explain the emission of electrons from a photosensitive surface with the help of Einstein's photoelectric equation?

The work function of the following metals is given : Na 2.75 ev, K = 2.3 eV, Mo = 4.17 eV and Ni = 5.15 eV. Which of these metals will not cause photoelectric emission for radiation of wavelength 3300 Å from a laser source placed 1 m away from these metals? What happens if the laser source is brought nearer and placed 50 cm away?

Define the term 'amplitude modulation'. Explain any two factors which justify the need for modulating a low-frequency base band signal.

A radioactive nucleus 'A' undergoes a series of decays as given below:

The mass number and atomic number of A₂ are 176 and 71 respectively. Determine the mass and atomic number of A₄ and A.

Write the basic nuclear process underlying β⁺ and β^- decays.

26.

For a CE-transistor amplifier, the audio signal voltage across the collector resistance of 2 kΩ is 2 V. Given the current amplification factor of the transistor is 100, find the input signal voltage and base current, if the base resistance is 1 kΩ. 

Mrs Rashmi Singh broke her reading glasses. When she went to the shopkeeper to order new specs, he suggested that she should get spectacles with plastic lenses instead of glass lenses. On getting the new spectacles, she found that the new ones were thicker than the earlier ones. She asked this question to the shopkeeper but he could not offer a satisfactory explanation for this. At home, Mrs Singh raised the same question to her daughter Anuja who explained why plastic lenses were thicker.

(a) Write two qualities displayed each by Anuja and her mother.

(b) How do you explain this fact using lens maker's formula?

A narrow beam of unpolarized light of intensity I0 is incident on a Polaroid P₁. The light transmitted by it is then incident on a second polaroid P₂ with its pass axis making the angle of 60° relatives to the pass axis of P1. Find the intensity of the light transmitted by P₂.

Explain two features to distinguish between the interference pattern in Young's double slit experiment with the diffraction pattern obtained due to a single slit.