Amit was driving a car and suddenly he heard a loud sound coming from behind. He looked through his rear view mirror and saw an ambulance. He gave the way to the ambulance. |
(i) What values did Amit exhibit? |
(ii) What type of mirrors are used as rear view mirror in automobiles and why? |
Explain the following terms used in communication system. |
(i) Attenuation |
(ii) Demodulation |
(iii) Amplification |
A semiconductor has equal electron and hole concentration of \[5\times {{10}^{8}}\text{ }{{m}^{-3}}.\] On doping with certain impurity, electron concentration increases to\[~8\times {{10}^{12}}\text{ }{{m}^{-3}}.\] |
(i) Identify the new semiconductor obtained after doping. |
(ii) Calculate the new hole concentration. |
(i) State Kirchhoff's rules for an electrical network. |
(ii) The plot of the variation of potential difference across a combination of three identical cells in series, versus current is as shown below, What is the emf of each cell? |
Sheela switched ON the radio set to listen her favourite music but found the reception was not clear. Also, there was overlapping of signals. So, she adjusted the tuner in the set till she heard the music clear. |
(i) Name the phenomenon involved in tunning a radio set to a particular station. |
(ii) What values are associated with Sheela? |
A boy, while crossing the road, saw an on overhead street light in the day time. Thinking it to be wastage of current and power, he switched OFF of the street light over when it was at some height on the pole and it was not easy for him to switch off. |
(i) What words would you frame for the little boy and his thinking? |
(ii) What is the basic working principle of a transformer? |
The half-life of a radioactive substance is 30s. |
Calculate |
(i) the decay constant. |
(ii) time taken for the sample to decay 3/4th of its initial value. |
Two persons are standing under a tree and another person near them is inside a car. They were arguing about going out for a movie or to the beach, when a lightning struck the tree with some force. The person inside the car notices his friends standing under the tree are affected by lightning, he comes out and takes them to the nearby hospital. |
(i) Why the person in the car was not affected by lightning? |
(ii) What quality to you find the person inside the car? |
(iii) Explain, the process that takes place during lightning. |
An emf \[E=100\,sin\,314\,t\] is applied across a pure capacitor of \[637\mu F.\] Find |
(i) the instantaneous current I |
(ii) instantaneous power P |
(iii) the frequency of power and |
(iv) the maximum energy stored in the capacitor. |
(i) Identify the semiconductor diode used. |
(ii) Draw the circuit diagram to obtain the given characteristic of this device. |
(iii) Briefly explain one important application of this diode. |
Draw a ray diagram to show the image formation in a refracting type Astronomical telescope when the final image is formed at infinity. Write down the expression for its magnifying power, why should the diameter of the objective of telescope to larger? |
Or |
What is total internal reflection? Explain with the help of a diagram, how this principle is used for transmission of video signals using optical fibres. |
Rahul saw his younger sister wondering with the emission of light from a vapour lamp. She anxiously asked to Rahul, how different lights, Rahul explained that phenomenon to her. She became happy after knowing the cause. |
(i) What are the values related to Rahul?s behavior? |
(ii) Which series in the H-spectrum is in the visible light? |
(iii) Calculate the minimum and maximum wavelengths for Balmer series. |
(i) Charge on each capacitor |
(ii) Equivalent capacitance of the network |
(iii) Energy stored in the network of capacitor |
(i) Distinguish between metals, insulators and semiconductors on the basis of energy bank diagram. |
(ii) Draw a circuit diagram showing the biasing of an LED. State the factor which controls |
(a) wavelength of light, |
(b) intensity of light emitted by the diode. |
Or |
(i) What is the difference between an intrinsic semiconductor and p-type semiconductor. Explain, why a p-type semiconductor is electrically neutral, although \[{{n}_{h}}>>{{n}_{e}}?\] |
(ii) In the figure given below, analyse the action of the gates (1) and (2) and identify the logic gate of the complete circuit so obtained. Give its symbol and the truth table. |
An electron and a positron are released from (0,0,0) and (0,0,1.51R) respectively, in a uniform magnetic field \[B={{B}_{0}}\hat{i},\] each with an equal momentum of magnitude p = eBR. Under what conditions on the direction of momentum will the orbits be non-intersecting circles? |
Or |
(i) Explain the elements of Earth's magnetic field and their meaning. Show these elements in a labelled diagram and deduce various relations between them, |
(ii) Horizontal and vertical components of Earth's magnetic field at a place are 0.15 G and 0.30 G, respectively Calculate the angle of dip and resultant intensity of Earth's magnetic field. |
(i) What do you mean by the polarisation of light? Define law of Malus and then show that the intensity of light become half when ordinary light is incident on a polariser. |
(ii) Two polarising sheets have their polarising direction parallel, so that the intensity of the transmitted light is maximum. |
Through what angle must the either sheet be turned, if the intensity is to drop by one half? |
Or |
(i) Consider a two slit interference arrangements (figure) such that the distance of the screen from the slits is half the distance between the slits. |
Obtain the value of D in terms of \[\lambda \] such that the first minima on the screen falls at a distance D from the centre O. |
(ii) Why are coherent sources required to create interference of light? |
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