Time: 2½ Hours

Cool off time : 15 Minutes

**General Instructions to Candidates**

- There is a ‘cool off-time’ of 15 minutes in addition to the writing time of 2½ hrs.
- In the ‘cool off time’ you are not permitted to write your answers or to discuss anything with others.
- Use the ‘cool off time’ to familiarize yourself with the questions and to prepare your answers.
- Read questions carefully before you answer.
- Only internal choice is allowed and all questions are compulsory.
- Selecting a question means answering all the sub-questions from that question.
- The answer sheet itself should include calculations, graphs, and figures.
- The questions are available in Malayalam as well.
- If necessary, provide equations.
- In the Examination Hall, electronic devices other than non-programmable calculators are not permitted.

Question 1.

A concave lens always produces ………….. images

i. real

ii. virtual

iii. magnified

iv. None of these

Question 2.

A Zener diode is always operated in …….. bias.

Question 3.

Momentum of a photon with wavelength λ is……

Question 4.

Write down the truth table of a NOR gate.

Question 5.

a. How many electrons constitute an electric charge of -16 µC?

(i) 10^{13}

(ii) 10^{14}

(iii) 10^{15}

(iv) 10^{12}

b. An electric dipole is a pair of equal and opposite point charges +q and -q separated by a distance r. Write an expression for its dipole moment.

c. When an electric dipole is subjected to a uniform electric field, what will happen?

Question 6.

A message signal of frequency 10kHz and peak voltage 10V is used to modulate a carrier of frequency 1 MHz and peak voltage 20V. Find the modulation index.

Question 7.

a. Resistivity of a conductor depends upon

(i) its material

(ii) its cross-sectional area

(iii) its length

(iv) All of the above

b. Calculate the current flowing through the following circuit :

c. A potentiometer is a device to measure emf of a cell. Explain how the emfs of two cells can be compared using a potentiometer.

Question 8.

a. Choose the wrong option.

(i) Volt = Weber / second

(ii) Weber = Henry x Ampere

(iii) Joule = Henry x Ampere²

(iv) Volt = Weber x Second

b. The current in a coil of self-inductance 0.1 H varies from 2A to 5A in a time of 1ms. Find the induced emf across the coil.

Question 9.

a. Sound waves do not exhibit

i. interference

ii. diffraction

iii. polarization

iv. reflection

b. Describe Young’s double-slit experiment to determine the bandwidth of the interference pattern.

OR

a. The intensity of scattered light I in Rayleigh scattering is proportional to……

b. Explain the diffraction pattern obtained due to a single slit and represent graphically the variation of intensity with angle of diffraction.

Question 10.

a. Define half-life period of a radioactive nucleus. Write down the relation connecting half-life period and mean life.

b. Define 1 amu. Calculate its energy equivalent in MeV.

Question 11.

Photoelectric current does not depend on energy of the radiation, but on its intensity. Explain?

Question 12.

a. Speed of light in glass is 2 x 10^{8} m/s. The Refractive index of glass is……

b. For an equilateral prism made of a material of refractive index √2 . find the angle of minimum deviation for a ray of monochromatic light.

c. Draw the ray diagram of a simple microscope that uses a single convex lens. Derive an expression for its linear magnification.

Question 13.

a. A dielectric slab is placed between the plates of a parallel plate capacitor. Its capacitance

i. becomes zero

ii. remains the same

iii. decreases

iv. increases

b. Derive an expression for energy stored in a capacitor.

Question 14.

a. At resonance, in an LCR circuit, the emf and current are

(i) in phase

(ii) out of phase

(iii) having a phase difference of π2

(iv) having a phase difference of π6

b. In the following circuit, find the value of V

OR

a. In a circuit carrying an ideal coil with negligible resistance, the power dissipated is …….

b. In the following circuit, find the impedance.

Question 15.

Explain hysteresis and draw hysteresis curve for a ferromagnetic substance.

Question 16.

Choose the appropriate values for X-rays from the given table.

Question 17.

a. Unit of wavenumber is

i. Hz

ii. eV

iii. m

iv. m^{-1}

b.Energy of ground state of a hydrogen atom is -13.6 eV. What is its ionization potential?

Question 18.

The current amplification factor for CB configuration of a transistor is 0.9. Find out the current amplification ion factor for CE configuration.

Question 19.

a. An electric charge q is moving with a velocity v in the direction of a magnetic field B. The magnetic force acting on the charge is

b. starting from Biot – Savart law, obtain an expression for the magnetic field at an axial point of a circular coil carrying current.

OR

a. An ammeter is a current measuring device which is always connected in an electric circuit.

b. Describe a cyclotron and obtain an expression for cyclotron frequency.