During the trip to Andaman, Swapnil went to Havloc beach to watch the sunset. He was amased to see the sun with its reddish appearance. Immediately he asked his father about this spectacular sky, His father explained him about this phenomena. |
Read the above passage and answer the following questions. |
(i) What is the cause of reddish appearance of sun at sunset? |
(ii) What values did Swapnil show? |
A silver wire has a resistance of \[2.1\Omega \] at \[27.5\,{}^{o}C\]and a resistance of \[2.7\Omega \] at \[100\,{}^{o}C.\] Determine the temperature coefficient of resistivity of silver. |
Or |
One billion electrons pass from a point A towards a point B in \[{{10}^{-4}}\] s. What is the current in milliamperes? What is its direction? |
In the figure given below, a coil B is connected to low voltage bulb L and placed parallel to another coil A as shown |
Explain the following observations. |
(i) Bulb lights up and |
(ii) Bulb gets dimmer if the coil B is moved upwards. |
(i) In the circuit given below, is the diode forward biased or reverse biased? |
(ii) What is the current flowing in the circuit given below? |
Anuj's father was having a constant back pain and fever for ten days. After a through medical check up, his father was diagnosed with Cancer. Now, he is going to the hospital after a regular interval of time for radiotherapy and feeling much better. |
Read the above passage and answer the following questions : |
(i) Which type of rays are used for treatment of Cancer and why? |
(ii) What basic values do you learn from this study? |
Calculate and compare the energy released by |
(i) fusion of 1 kg of hydrogen deep with in Sun and |
(ii) the fission of 1kg of \[{}^{235}U\] in a fission reactor. |
An \[\alpha -particle\]and proton are accelerated from the state of rest through the same Potential difference, V. Find the ratio of de-Broglie wavelengths associated with them. |
Or |
If light of wavelength \[\lambda =4000\overset{{}^\circ }{\mathop{A}}\,\] and intensity \[100\text{ }W/{{m}^{2}}\] incident on a metal plate of threshold frequency \[5.5\times {{10}^{14}}\text{ }Hz.\] |
What will be the maximum kinetic energy of photoelectron and number of photons incident per \[{{m}^{2}}\] per second. \[(h=6.6\times {{10}^{-34}}Js).\] |
During the Physics period, Mr. Neogi, Raju's Physics teacher was explaining to him and his friends about nuclear force and nuclear stability. He also explained them that stable nuclei like iron or sulphur have more neutrons than protons. He also explained nuclear fission and binding energy curve on the board. |
Read the above passage and answer the following questions: |
(i) Draw a graph showing the variation of binding energy per nucleon with mass number. |
(ii) Give the reason for the decrease of binding energy per nucleon for nuclei with high mass numbers. |
(iii) What are the values shown by Raju's Physics teacher? |
An object is placed exactly midway between a concave mirror of radius of curvature 40 cm and a convex mirror of radius of curvature 30 cm. |
The mirrors face each other and are 50 cm apart. Determine the nature and position of image formed by successive reflections first at the concave mirror and then at the convex mirror. |
(i) Why are Si and GaAs preferred materials for solar cells? |
(ii) Describe briefly with the help of a necessary circuit diagram, the working principle of a solar cell. |
(i) Find the potential difference between the ends A and B of the potentiometer. |
(ii) Would the method work, if the battery \[{{E}_{1}}\]is replaced by a cell of emf of 1 V? |
(iii) Does the high resistance R, used in the secondary circuit affect the balance point? Justify your answer. |
(i) A metallic piece becomes very hot when it is surrounded by a coil carrying high frequency alternating current. |
(ii) A rectangular loop of area \[20\,cm\times 30\,cm\] is placed in magnetic field of 0.3T, with its plane |
(a) inclined \[30{}^\circ \] to the field. |
(b) parallel to the field. |
Find out the magnetic flux linked with the loop. |
The teacher asked the students, "why we are calling the world today as the global village". |
One student Rabat replied due to modem generalised communication among the countries across the world, is leading various types of commercial and traditional relationships between them. |
(i) Do you agree with Rabat's reply? If yes, then why? Justify. |
(ii) Draw a block diagram of a generalized communication system. |
(iii) What are the two values shown by Rahat? |
Two spheres carrying charges \[1.5\mu C\] and \[2.5\mu C\] are located 30 cm apart. Find the potential and electric field |
(i) at mid-point of the line joining the two charges. |
(ii) at a point 10 cm from this mid-point in a plane normal to the line passing through the mid-point. |
Hence, calculate the angle \[(\alpha )\] subtended by the resultant intensity of electric field in case (ii). |
Or |
(i) Deduce the expression for the energy density stored in a charged capacitor. |
(ii) Show that the effective capacitance C, of a series combination, of three capacitors \[{{C}_{1}},{{C}_{2}}\] and \[{{C}_{3}}\] is given by |
Draw a schematic diagram of a step up transformer. Explain the working principle. Deduce the expression for the secondary to primary voltage in terms of the number of turns in the two coils. In an ideal transformer, how is this ratio related to the currents in the two coils? How is the transformer used in large scale transmission and distribution of electrical energy over long distances. |
Or |
In an AC circuit containing a prime inductor, show that the voltage is ahead of current by \[\frac{\pi }{2}\] in phase. Draw the phasor diagram for the circuit and the graph of V and i versus \[\omega t.\] |
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