Q. Write the relation for the speed of electromagnetic waves in terms of the amplitudes of electric and magnetic fields.

Q. A bar magnet is moved in the direction indicated by the arrow between two coils PQ and CD. Predict the direction of the induced current in each coil.

Q. Unpolarised light is passed through a polarised $P_1$. When this polarised beam passes through another polarised $P_2$ and if the pass axis of $P_2$ makes angle $\theta$ with the pass axis of $P_1$, then write the expression for the polarised beam passing through $P_2$. Draw a plot showing the variation of intensity when $\theta$ varies from $0$ to $2\pi$.

Q. (a) Define wave-front. Use Huygen's principle to verify the laws of refraction.
(b) How is linearly polarised light obtained by the process of scattering of light? Find the Brewster angle for air- glass interface, when the refractive index of glass $=1.5$.

Q. A double convex lens is made of a glass of refractive index $1.55$, with both faces of the same radius of curvature. Find the radius of curvature required, if the focal length is $20$cm.

Q. Nichrome and copper wire of same length and same radius are connected in series. Current $I$ is passed through them. Which wire gets heated up more? Justify your answer.

Q. The short wavelength limit for the Lyman series of the hydrogen spectrum is $913.4\stackrel{o}{A}$. Calculate the short wavelength limit for Balmer series of the hydrogen spectrum.

Q. What was the installation at Chernobyl where the disaster took place? What, according to you, was the cause of this disaster?

Q. Explain giving reasons for the following.
(a) Photoelectric current in a photocell increases with the increase in the intensity of the incident radiation.
(b) The stopping potential $\left(V_0\right)$ varies linearly with the frequency $\left(\nu \right)$ of the incident radiation for a given photosensitive surface with the slope remaining the same for different surfaces.
(c) Maximum kinetic energy of the photo-electrons is independent of the intensity of incident radiation.

Q. How does the angle of minimum deviation of a glass prism vary, if the incident violet light is replaced by red light? Give reason.

Q. Name the phenomenon which shows the quantum nature of electromagnetic radiation.

Q. Write two properties of a material suitable for making (a) a permanent magnet, and (b) an electromagnet.

Q. Define self-inductance of a coil. Obtain the expression for the energy stored in an inductor L connected across a source of emf.

Q. (a) The potential difference applied across a given resistor is altered so that the heat produced per second increases by a factor of $9$. By what factor does the applied potential difference change?
(b) In the figure shown, an ammeter A and a resistor of $4\Omega$ are connected to the terminals of the source. The emf of the source is $12$V having an internal resistance of $2\Omega$. Calculate the voltmeter and ammeter reading.

Q. Monochromatic light of wavelength $589$nm is incident from air on a water surface. If $\mu$ for water is $1.33$, find the wavelength, frequency and speed of the refracted light.

Q. Two identical loops P and Q each of radius $5$cm are lying in perpendicular planes such that they have a common centre as shown in the figure. Find the magnitude and direction of the net magnetic field at the common centre of the two coils, if they carry currents equal to $3$A and $4$A respectively.

Q. Draw the intensity pattern for single slit diffraction and double slit interference. Hence, state two differences between interference and diffraction patterns.

Q. Identify the electromagnetic waves whose wavelengths lie in the range.
(a) ${10}^{-11}m<\lambda <{10}^{-14}$m.
(b) ${10}^{-4}m<\lambda <{10}^{-6}$m.
Write one use of each.

Q. Draw a ray diagram showing the formation of image by a reflecting telescope.

Q. Define mutual inductance between a pair of coils. Derive an expression for the mutual inductance of two long coaxial solenoids of same length wound one over the other.

Q. Two identified parallel plate capacitors $A$ and $B$ are connected to a battery of $V$ volts with the switch $S$ closed. The switch is now opened and the free space between the plates of the capacitors is filled with a dielectric of dielectric constant $K$. Find the ratio of the total electrostatic energy stored in both capacitors before and after the introduction of the dielectric.

Q. Write two advantages of a reflecting telescope over a refracting telescope.

Q. Draw a block diagram of a generalized communication system. Write the functions of each of the following.
(a) Transmitter
(b) Channel
(c) Receiver.

Q. (a) How is amplitude modulation achieved?
(b) The frequencies of two side bands in an AM wave are $640$ kHz and $660$ kHz respectively. Find the frequencies of carrier and modulating signal. What is the bandwidth required for amplitude modulation?

Q. (a) In the following diagram, which bulb out of $B_1$ and $B_2$ will glow and why?
(b) Draw a diagram of an illuminated p-n junction solar cell.
(c) Explain briefly the three processes due to which generation of emf takes place in a solar cell.

Q. Explain the process of release of energy in the installation at Chernobyl.

Q. (a) Draw the circuit diagram for studying the characteristics of a transistor in common emitter configuration. Explain briefly and show how input and output characteristics are drawn.
(b) The figure shows input waveform A and B to a logic. Draw the output waveform for an OR gate. Write the truth table for this logic gate and draw its logic symbol.

Q. Find the condition under which the charged particles moving with different speeds in the presence of electric and magnetic field vectors can be used to select charged particles of a particular speed.

Q. What, according to you, were the values displayed by Asha and her mother?

Q. (a) Write the principle of working of a metre bridge.
(b) In a metre bridge, the balance point is found at a distance $l_1$ with resistances R and S as shown in the figure. An unknown resistance X is now connected in parallel to the resistance S and the balance point is found at a distance $l_2$. Obtain a formula for X is terms of $l_1,l_2$ and S.