While performing experiment on Ohm's law in laboratory, Bhupesh used a bulb as a resistance in the circuit. When he plotted voltage-current graph, he got curved line instead of straight line. He was upset, went to Physics teacher and teacher explained him about the erronous result. Now, Bhupesh identified his mistake. |
Read the above passage and answer the following questions : |
(i) Why the experiment performed by Bhupesh was giving faulty result? |
(ii) What values are shown by Physics teacher? |
A diode is connected to 220 V (rms) AC in series with a capacitor, as shown in figure. What is the voltage V across the capacitor? |
Merrie Curie and her teacher turned husband Pierre Curie worked hard to extract radium chloride \[(RaC{{l}_{2}})\] from uranium ore. They succeeded in 1902 after a long struggle. About 0.19 g of \[RaC{{l}_{2}}\] was extracted and its radioactivity was studied. They were awarded by the nobel prize, which they shared it with Henri Becquerel. |
(i) What are the values shown by Merrie Curie and her husband? |
(ii) The sequence of stepwise decays of a radioactive nucleus is \[D\xrightarrow{\alpha }{{D}_{1}}\xrightarrow{{{\beta }^{-}}}{{D}_{2}}\] |
If the nucleon number and atomic number of \[{{D}_{2}}\] are 176 and 71, respectively, then what are the corresponding values of D and\[{{D}_{1}}?\] |
Justify your answer in each case. |
In a single slit experiment, how is the angular width of central bright maximum changes, when |
(i) the slit width is decreased. |
(ii) the distance between the slit and the screen is increased. |
(iii) light of smaller wavelength \[\lambda \] is used. |
(i) A circular coil of 30 turns and radius 8 cm carrying a current of 6 A is suspended vertically in a uniform horizontal magnetic field of magnitude 1 T. The field lines make an angle \[60{}^\circ \] with the normal of the coil. Calculate the magnitude of the counter torque that must be applied to prevent the coil from turning. |
(ii) Would your answer change, if the circular coil were replaced by a planar coil of some irregular shape that encloses the same area? (All other particulars are also unaltered). |
Or |
Explain the following. |
(i) Why do magnetic lines form continuous closed loops? |
(ii) Why are the field lines repelled (expelled) when a diamagnetic materials is placed in an external uniform magnetic field? |
Ridhima noticed a ragman who used to come to her house frequently was getting weak, nails were turning blue and he had starting losing hair and weight. This happened immediately after he purchased a big container from a nuclear reactor plant as waste. She immediately admitted him in hospital and started treatment. |
(i) Which possible reason was responsible for ragman's ill health? |
(ii) Which value is reflected in Ridhima's advise? |
Electromagnetic waves with wavelength |
(i) \[{{\lambda }_{1}}\] is used in satellite communication |
(ii) \[{{\lambda }_{2}}\] is used to kill germs in water purifiers |
(iii) \[{{\lambda }_{3}}\] is used to detect leakage of oil in underground pipelines |
(iv)\[{{\lambda }_{4}}\] is used to improve visibility in runways, during fog and mist conditions |
(a) Identify and name the part of electromagnetic spectrum to which these radiations belong |
(b) Arrange the wavelengths in ascending order of their magnitude |
The intensity at the central maxima (O) in a Young's double slit experimental is \[{{I}_{0}}.\] the distance OP equals one-third of fringe width of the pattern, then show that the intensity at point P would be \[{{I}_{0}}/4.\] |
Young s double slit experiment |
Rakhi got a new diamond ring by her mother on her 18th birthday. She shared with her best friend Neelima and showed her the ring too. She amazed to see the brilliance of diamond and wanted to know the reason behind it. Neelima, than gave her brief explanation of her queries. |
(i) Which two values are displayed by Neelima in responding to Rakhi's queries? |
(ii) Three light rays, red (R), green (G) and blue (B) are incident on a right angled prism ABC at face AB. The refractive indices of the material of the prism for red, green and blue wavelengths are 1.39, 1.44 and 1.47, respectively. Out of the three, which colour of ray will emerge out of face AC? Justify your answer. |
Light rays are incident on a right angled prism, ABC |
How is the mutual inductance of a pair of coils affected when, |
(i) separation between the coils is increased |
(ii) the number of turns in each coil is increased |
(iii) a thin iron sheet is placed between the two coils, other factors remaining the same? |
Explain your answer in each case. |
Find an expression for the force acting per unit length between two straight parallel current carrying conductors and hence define one ampere current. |
Or |
In a given figure, a rectangular current carrying loop placed 2 cm away from a long, straight, current carrying conductor, What is the magnitude and direction of the net force acting on the loop? |
When a circuit element 'X' is connected across an AC source, a current of \[\sqrt{2}\] A flows through it and this current is in phase with the applied voltage. When another element' Y' is connected across the same AC source, the same current flows in the circuit but it leads the voltage by \[\pi /2\] radians. |
(i) Name the element X and Y. |
(ii) Find the current that flows in the circuit when series combination of X and Y is connected across the same voltage. |
(iii) Plot a graph showing variation of the net impedance of this series combination of X and Y as a function of the angular frequency of the applied voltage. |
(i) What values are displayed by the teacher? |
(ii) Which terminal positive or negative of the cell \[{{E}_{1}}\] is connected at X in case (a) and how is \[{{E}_{1}}\] related to E? |
(iii) What is the advantage of using thick metallic strips to join wires in a potentiometer? |
Find an expression for the torque acting on an electric dipole placed in uniform electric field. A system of two charges \[{{q}_{A}}=2.5\times {{10}^{-7}}C\] and \[{{q}_{B}}=-2.5\times {{10}^{-7}}C\] located at points \[A(0,0-15)cm\] and \[B(0,0,+15)\,cm,\] respectively. |
Find the electric dipole moment of the system and the magnitude of the torque acting on it, when it is placed in a uniform electric field \[5\times {{10}^{4}}\,N{{C}^{-1}},\] making an angle of \[30{}^\circ ,\] with the Z-axis. |
Or |
A capacitor of capacitance C is charged fully by connecting it to a battery of emf E. It is then disconnected, from the battery. If the separation between the plates of the capacitor is now doubled, what will |
(i) capacitance of the capacitor |
(ii) charge stored by the capacitor |
(iii) potential difference across it |
(iv) field strength between the plates |
(v) energy stored by the capacitor? |
Draw the circuit diagram of a common-emitter amplifier using an n-p-n transistor. Draw the input and output waveforms of the signal and also find the expression for its voltage gain. |
Or |
Explain with the help of a circuit diagram, the use of p-n junction diode as a half-wave rectifier. Draw a sketch of the input and output waveforms. |
(i) Draw the ray diagram for the formation of image of an object by a convex mirror and use it (along with the sign convention) to derive mirror formula. |
(ii) Use the mirror formula to show that an object kept between the pole and focus of a concave mirror then the image appears to be formed behind the mirror. |
Or |
With the help of a ray diagram, show the formation of image of a point object by refraction of light at a spherical surface separating two media of refractive indices \[{{n}_{1}}\] and \[{{n}_{2}}\] \[({{n}_{2}}>{{n}_{1}}),\] respectively. Using this diagram, derive the relation |
\[\frac{{{n}_{2}}}{v}-\frac{{{n}_{1}}}{u}=\frac{{{n}^{2}}-{{n}_{1}}}{R}\] |
Write the sign conventions used. |
An unsymmetrical double convex thin lens forms the image of a point object on its axis. Will the position of the image change, if the lens is reversed? |
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