Question Paper (Section wise)
Mobility of electron in a semiconductor is defined as the ratio of their velocity to the applied electric field. If, for an n-type semiconductor, the density of electrons is 1019 m-3 and their mobility is 1.6 m2 / (V. s) then the resistivity of the semiconductor (since it is an n-type semiconductor contribution of holes is ignored) is close to:
A copper wire is stretched to make it 0.5% longer. The percentage change in its electric resistance if its volume remains unchanged is
When the switch S, in the circuit shown is closed, then the value of current I will be
Consider the nuclear fission Ne20 → 2He4 + C12. Given that the binding energy/ nucleon of Ne20, He4 and C12 are, respectively, 8.03 MeV, 7.07 MeV, and 7.86 MeV, Identify the correct statement:
Charges – q and + q located at A and B, respectively, constitute an electric dipole. Distance AB = 2a, O is the mid-point of the dipole OP is perpendicular to AB. A charge Q is placed at P where OP = y and y >> 2a. The charge Q experience an electrostatic force F. If Q is now moved along the equatorial line to P’ such that , the force on Q will be close to:
A rigid massless road of length 3I has tow masses attached at each end as shown in the figure. The rod is pivoted at point P on the horizontal axis ( see figure). When released from initial horizontal position, its instantaneous angular acceleration will be :
There are two long co – axial solenoids of same length I. The inner and outer coils have radii r1 and r2 and number of turns per unit length n1 and n2 respectively. The ratio of mutual inductance to the self – inductance of the inner – coil is:
The resistance of the meter bridge AB in given figure is 4Ω With a cell emf ε=005 V and rheostat resistance Rh =2Ω the full point is obtained at some point J. When the cell is replaced by another one of emf ε = ε2 the same null point J is found for Rn=6 Ω. The emf ε2 is:
If the de Broglie wavelength of an electron is equal to 10-3 times the wavelength of a photon of frequency 6 × 1014 Hz, then the speed of electron is equal to: (Speed of light=3 × 10=8=m/s; Planck’s constant=6.63 × 10-34J.s; Mass of electron=9.1 × 10-31Kg)
Two satellites, A and B, have masses m and 2m respectively. A is in a circular orbit of radius R, and B is in a circular orbit of radius 2R around the earth. The ratio of their kinetic energies, TA / TB, is:
A block kept on a rough inclined plane, as shown in the figure, remains at rest upto a maximum force 2 N down the inclined plane. The maximum external force up the inclined plane that does not move the block is 10 N. the coefficient of static friction between the block and the plane is:
[Take g = 10 m / s2]
Two particles A, B are moving on two concentric circles of radii R1 and R2 with equal angular speed ω. At t = 0, their positions and direction of motion are shown in the figure:
The relative velocity is given by:
A parallel plate capacitor has 1µF capacitance. One of its two plates is given + 2µC charge and the other plate, +4µC charge. The potential difference developed across the capacitor is:
In a line of sight radio communication, a distance of about 50 km is kept between the transmitting and receiving antennas. If the height of the receiving antenna is 70m, then the minimum height of the transmitting antenna should be: (Radius of the Earth = 6.4×106m)
The very long, straight and insulated are kept at 90° angle from each other In xy – plane as shown in the figure.
These wires cary currently of equal magnitude I, whose directions are shown in the figure. The met magneti field at point P will be:
The figure shows a Young’s double slit experimental setup. It is observed that when a thin transparent sheet of thickness t and refractive index μ is put in front of one of the slits, the central maximum gets shifted by a distance equal to n fringe widths. If the wavelength of light used is λ, t will be:
The stream of a river is flowing with a speed of 2 km/h. A swimmer can swim at a speed of 4 km/h. What should be the direction of the swimmer with respect to the flow of the river to cross the river straight?
The pressure wave, P = 0.01 sin [1000t – 3x] NM–2, corresponds to the sound produced by a vibrating blade on a day when atmospheric temperature is 0°C. On some other day when temperature is T, the speed of sound produced by the same blade and at the same frequency is found to be 336 ms–1. Approximate value of T is:
Two blocks A and B of masses mA = 1kg and mB = 3 kg are kept on the table as shown in figure. The coefficient of friction between A and B is 0.2 and between B and the surface of the table is also 0.2. The maximum force F that can be applied on B horizontal, so that the block A does not slide over the block B is:
The formula X = 5YZ2 X and Z have dimensions of capacitance and magnetic field respectively. What are the dimensions of Y in Sl units?
In a Young’s double slit experiment the ratio of the slit’s width is 4:1. The approximate value of ratio of the intensity of maxima to minima, close to central fringe on the screen will be _______.
A man (mass = 50 kg) and his son (mass = 20 kg) are standing on a frictionless surface facing each other. The man pushes his son so that he starts moving at a speed of 6 ms-1 with respect to the man. The speed of the man with respect to the surface is ______ m/s.
The transfer characteristic curve of a transistor, having input and output resistance 100 Ω and 100 kΩ respectively, is shown in the figure. For the given case the Voltage gain is ________ kV.
A gas can be transported from point A to point B using one of two processes: ACB or ADB. When the path ACB is used, 40 J of heat enters the system. If path ADB is used, the system's work down is 10 J, and the heat flow into the system in path ADB is _____ J.
A conducting circular loop made of a thin wire, has area 3.5 × 10-3 m2 resistance 40 Ω. It is placed perpendicular to a time dependent magnetic field B(t) = (0.4T) sin (50πt). The field is uniform in space. Then the net charge flowing through the loop during t = 0 s and t = 10 ms is close to ______ μC.