physics midterm preparatory exam, ISc-ii, ICSE (also good for CBSE/XII) Reply

Question 9

Describe the Bohr model for atom and point out its drawbacks. Write the nth level energy of a Hydrogen atom. Calculate the emission energy of a Hydrogen atom if an electron jumps from n=10 to n=3 level. What are Ka and Kb lines in characteristic X-ray emission? Explain their origin through electronic transitions.

Question 11

Describe the Millikan’s experiment for electron charge e. Derive in necessary steps how e would be determined by this set up from various known parameters. Explain your steps with the concepts.

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Physics class tests, junior college, XII/CBSE/ICSE Reply

Subjective {14 questions carry 2 marks each, all to be answered}

8. If threshold frequency is 5×104 Hz whats the work function of the metal in eV or Joule?

9. 3 capacitors c1=5 µF each are in series, whats their equivalent resistance?

10. 3 capacitors c1=5 µF each are in parallel combination, whats their equivalent resistance?

11. If a potential difference of 3 V is applied at two ends of a 60 cm long metal wire with current density = j = 10-7 A/m2 whats conductivity of the wire? More…

Physics class tests, XII/ICSE/CBSE Reply

3. Why Ka and Kb lines are produced (chose only one appropriate answer)

A. electronic transitions B. Atomic collisions

C. Radioactive decay D. Nuclear transmutation

4. Exactly why there is quantization of physical variables such as momentum, angular momentum, energy, orbital distance and speed?

A. wave-particle duality B. Interference of waves

C. Particle acceleration to speed of light D. Resistance experienced by particles in conductors

5. Cathode rays are streams of

A. electrons B. x-rays

C. nucleons D. high atomic number elements More…

Physics class tests for XII/ICSE/CBSE Reply

Question 1

Derive potential due to an electric dipole in a general direction making an angle J with dipole axis. Use E = -dV/dr to obtain E in general direction.

Question 2

Derive electric field in the end-on and broad-on position for a dipole vector P = p 2Q.a, where P is the vector and p the unit vector along the same.

Question 3

Describe the Rutherford’s model of the atom. Explain the results of the Geiger-Marsden experiment with a diagram. Mention the Rutherford’s model’s drawback. More…

Physics Class tests for Junior college (PUC/ISc/XII/CBSE/ICSE) Reply

Question 7

(a) Cyclotron frequency is proportional to energy (b) depends on magnetic field

Question 8

Angular Momentum L is an integral multiple of which constant?

(a) Fine structure constant

(b) Rydberg Constant

(c) Universal Gas Constant

(d) Planck’s Constant

Question 9

Ground state speed of e- in the H-atom in terms of speed-of-light c is

(a) c/137 (b) c.137 (c) a.c/137 (d) c/10

Question 10

Whats the energy of H-atom according to Niels Bohr?

(a) -13.61/n2 eV (b) +13.61/n2 eV (c) -13.61/n eV (d) -13.61 eV More…

Homework questions of Physics for Junior college (PUC, ISc, XII, CBSE, ICSE) Reply

Question 3

Deuteron is a bound state of a neutron (n) and a proton (p) with a binding energy BE = 2.2 MeV. A g-ray of energy E is aimed at a deuteron nucleus to try to break it into a neutron and proton so that n and p move in direction of incident g ray. If E = B.E. show that this is not possible. How much should BE be so that such a process can occur.

Question 4

Total charge –Q is uniformly distributed along length of a ring of radius R. A small test charge = q of mass m is kept at center of ring and is given a gentle push along the axis of the ring. More…