Question
Explain the concept of energy bands with a figure.
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A monoenergetic (18 keV) electron beam initially in the horizontal direction is subjected to a horizontal magnetic field of 0.04 G normal to the initial direction. Estimate the up or down deflection of the beam over a distance of 30 cm (me = 9.11 × 10–19 C).
[Note: Data in this exercise are so chosen that the answer will give you an idea of the effect of earth’s magnetic field on the motion of the electron beam from the electron gun to the screen in a TV set.]
[Note: Data in this exercise are so chosen that the answer will give you an idea of the effect of earth’s magnetic field on the motion of the electron beam from the electron gun to the screen in a TV set.]
An electric current flows in a wire from north to south. What will be the direction of the magnetic field due to this wire at a point east of the wire? West of the wire? Vertically above the wire? Vertically below the wire?
- Draw a labelled ray diagram to obtain the real image formed by an astronomical telescope in normal adjustment position. Define its magnifying power.
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- Which lenses should he used as objective and eyepiece? Justify your answer.
- Why is the aperture of the objective preferred to be large?
Consider a wire of length 4m and cross-sectional area 1mm2 carrying a current of 2A. If each cubic metre of the material contains 1029 free electrons, find the average time taken by an electron to cross the length of the wire.
With the help of a labelled diagram, explain how does an AC works. There are $N$ turns in coil of AC generator. Area of each turn is A and the coil is rotating with a uniform angular velocity. Establish an expression for generated induced electromotive force. What is the source of energy production by this method?
→Find out magnetic force on parallel current carrying conductors and also state their special conditions.
A charge of 8 mC is located at the origin. Calculate the work done in taking a small charge of –2 × 10–9 C from a point P (0, 0, 3 cm) to a point Q (0, 4 cm, 0), via a point R (0, 6 cm, 9 cm).
Find the currents through the three reaiators shown in figure.
A rectangular frame of wire abcd has dimensions 32cm × 8.0cm and a total resistance of $2.0\Omega.$ It is pulled out of a magnetic field B = 0.020T by applying a force of 3.2 × 10-5N (figure). It is found that the frame moves with constant speed. Find
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- The emf induced in the loop.
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i. A coin is placed inside a denser medium. Why does it appear to be raised? Obtain an expression for the height through which the object appears to be raised in terms of refractive index of the medium and real depth.
ii. A compound microscope consists of an objective lens of focal length 2 cm and an eyepiece of focal length 6.25 cm separated by a distance of 15 cm. How far from the objective should an object be placed in order to obtain the final image at the least distance of distinct vision (25 cm)? Calculate the magnifying power of the microscope.
ii. A compound microscope consists of an objective lens of focal length 2 cm and an eyepiece of focal length 6.25 cm separated by a distance of 15 cm. How far from the objective should an object be placed in order to obtain the final image at the least distance of distinct vision (25 cm)? Calculate the magnifying power of the microscope.