Short Answer TypeHow 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.
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) Two qualities displayed each by Anuja and her mother:
Anuja has good knowledge of lens and she is very co-operative.
Mrs Rashmi is curious to know about lenses and science behind it.
(b)The lens maker formula is given as 
where f is the focal length, μ is the refractive index and R1 and R2 is the radius of curvature of the lens.
Since μg>μp
where g stands for glass and p stands for plastic
Therefore, we get (μ-1)> (μp-1)
Now, using the lens maker formula, we see that focal length is inversely proportioned to (μ-1)
Hence, fp>fg
Thus, in the case of the plastic lens, the thickness of the lens should be increased to keep the same focal length as that of the glass lens to give the same power.
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.
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