Q.1 An electron is moving with a velocity of 107m/s enters a uniform magnetic field of 1T. The direction of velocity of the electron is perpendicular to the magnetic field. What would be the trajectory of electron in this field?
Q.2 An equiconvex lens of focal length 15cm is cut into two halves along the plane perpendicular to the principle axis. What is the focal length of each half?
Q,3 for circuits used for transporting electric power, a low power factor implies large power less in transmission. Explain?
Q.4 What is the shortest wavelength present in Brackett series of the hydrogen spectra?
Q.5 Show graphically how the stopping potential for a given photosensitive surface varies with frequency of incident radiation.
Q.6 Show by diagram that two infinitely long parallel wires carrying equal currents will attract each other. Mark the direction of current, magnetic field and force.
Q.7 Calculate the refractive index of the material of equilateral prism for which the angle of minimum deviation is 600.
Q,8 The electric field at a point due to point charge is 30N/C and the electric potential at that point is 15J/C. Find the magnitude of the charge and the distance of the point from the point charge.
Q.8 A uniform electric field of 5000N/C along positive x axis exists in space, find the flux of this field through a square of 10cm on side whose plane is parallel to the y-z plane. What would be the flux through the same square if the plane makes an angle of 300 with the x axis.
Q.9 A charge particle q is placed at a distance x from the center of short electric dipole on its axial line. Find the work done to move the charge from that point to the center of electric dipole.
Q.10 Out of the two magnetic material , A has relative permeability slightly less than unity and B has relative permeability very much greater than one. Identify the nature of magnetic materials A and B. How will the magnetic lines of force of uniform magnetic field distort if these materials are placed in uniform field.
Q.11 State the condition for maxima and minima in single slit diffraction pattern and thus using this relation find the width of central maxima for slit width ‘d’ on a screen placed at a distance D using wavelength λ.
Q.12 How can we use NAND gate to form OR gate. Write truth table for OR gate.
Q.13 State Kirchoff’s rules. Explain briefly the conservation laws on which these rules are based.
Q.14 An athlete paddles a stationary tricyle whose pedals are attached to a coil having 100 turns each of area 0.1m2. the coil is lying in XY plane and is rotated in this plane at 50rpm about y axis where uniform magnetic field B=0.01T along positive z axis is present. Find the [a] maximum emf [b] the average emf generated in the coil over one complete revolution.
Q.15 State the principle on which Cyclotron is based. Explain briefly how this machine is used to accelerate charge particles to high energies. Why it can’t accelerate neutron.
Q.16 Use Gauss law to find electric field intensity of large sheet. Use the result and diagrammatically find the electric field intensity for two large oppositely charge sheets having surface charge density σ and –σ.
Q.17 A proton and deuteron are accelerated through same accelerating potential. Which one of the two has [a] greater value of de-Broglie wavelength associated with it [b] less momentum . Give reasons to justify your answers.
Q.18 [a]Monochromatic light of frequency 6 x 1014Hz is produced by a laser. The power emitted is 2mW. Estimate the number of photons emitted per second by the source.
[b] Draw a plot showing variation of photoelectric current versus the intensity of incident radiation on a given photosensitive surface.
Q.19 Use mirror formula to show that a convex mirror always produces a virtual image independent of the location of the object.
[b] Use lens equation to deduce algebraically that the object placed within focus of convex lens produces a virtual and enlarged image.
Q.20 Draw plot showing variation of amplitude versus frequency for an amplitude modulated wave. Define modulation index. State its importance in effective amplitude modulation.
Q.21 [a] Give the ratio of number of holes and number of conduction electrons in an intrinsic semiconductor.
[b] How does the energy gap in intrinsic semiconductor vary when doped with trivalent impurity
[c] Drae I vs V graph for forward biased pn junction diode.
Q.22 With the necessary circuit diagram, describe briefly how npn transistor in CE configuration amplifies a small sinusoidal voltage. Write expression for ac current gain and voltage gain.
Q.23 When Aman a physics student of class XII came to know that her parents are planning to rent out top floor of the house to a mobile company he protested. He tried hard to convince his parents that this would be health Hazard and his parents agreed. [a] In what way setting up of transmission power by a mobile company prove injurious to health? [b] By objecting to the plans of his parents, what values does he display? [c] Estimate the range of em waves which can transmitted by antenna of height 20m.
Q.24 [a]State and prove principle of potentiometer. How it be used to find the internal resistance of the cell.
[b]A potentiometer wire of length 1m has a resistance of 5 ohm. It is connected to a 8V battery in series with a resistance of 15 ohm. Determine the emf of the primary cell which gives balance point at 60cm.
Q.25 Draw a labeled diagram showing formation of final image at least distance of distinct vision by a compound microscope.
[b] A convex lens of focal length 20cm is placed coaxially with convex mirror of radius of curvature 20cm. The two are kept 15cm apart. A point object is placed 40cm in front of the convex lens. Find the position of image formed by this combination. Draw the ray diagram showing the image formation.
Q.26 Draw a schematic diagram of an AC generator describing its basic elements. State briefly its working and principle. Show a plot of variation of [a] magnetic flux [b] alternating emf versus time generated by a loop of wire rotating in magnetic field .
[c] Why is choke coil needed in the use of fluorescent tubes with ac mains.