## Physics midterm exam, class XII (ISc-II) ICSE (also good for PU/CBSE)

Question 11

Describe the Thomson’s e/m experiment by mutually perpendicular set-up of electric field and magnetic field; E and B. Derive in necessary steps how e/m would be determined by this set up from various known parameters such as E and B values.

Question 12

Threshold wavelength of Tungsten is 2400 Angstrom. Tungsten is illuminated by a light of wavelength 1600 Angstrom. Whats the value of work function, maximum kinetic energy of electrons and stopping potential. Describe the ideas of Photoelectric effect. Who discovered photoelectric effect? Which scientist successfully explained this effect?

## Physics midterm questions, for class XII (CBSE/PU but also good for ICSE)

Question 6

Derive the expression for the capacitance of a configuration where two plates are kept distance d apart when a material of thickness t with dielectric constant K is inserted in-between.

Question 7

Derive the magnetic field B of a Toroid by using Ampere’s circuital law.

Question 8

State the Ampere circuital law and define magnetic flux. State the right hand thumb rule for magnetic field created by electric current. From the Lorentz Force expression derive the force acting on a current element of length l by a magnetic field B.

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

Question 7

Derive the magnetic field B of a Solenoid by using Ampere’s circuital law.

Question 8

State the Ampere circuital law and define magnetic flux. State the Maxwell’s cork screw rule. From the Lorentz Force expression derive the force acting on a current element of length l by a magnetic field B.

This question is Compulsory (5×1)
Question 9

Describe the mechanism of a cathode ray tube with a neat and labeled diagram. Write a short history of how electrons were discovered. What is X-ray emission? What are Ka and Kb lines?

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

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.

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

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?

## Physics class tests, XII/ICSE/CBSE

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