NEXT TOPPER INSTITUTE FOR JEE ,NEET, CBSE

1.To which part of the electromagnetic spectrum does a wave of frequency 5 x 10 19  Hz belong?    2.To which part of the electromagnetic spectrum does a wave of frequency 3 x 10 13  Hz belong?    3.Write the condition under which an electron will move undeflected in the presence of crossed electric and magnetic fields.   4.Welders wear special goggles or face masks with glass windows to protect their eyes from electromagnetic radiation. Name the radiations and write the range of their frequency.  5.What are the directions of electric and magnetic field vectors relative to each other and relative to the direction of propagation of electromagnetic waves?  6.Name the electromagnetic waves which (i) maintain the earth’s warmth and (ii) are used in aircraft navigation.  7.A plane electromagnetic wave travels in vacuum along Z- direction. What can you say about the direction of electric and magnetic field vectors...

1. (a) Two magnets are lying side by side as shown below. Draw magnetic field line between poles P and Q. (b) What does the degree of closeness of magnetic field lines near the poles signify? Answer. (b) The degree of closeness of magnetic field lines near the poles signify that the field is stronger there, i.e. the pole of another magnet when placed in the magnetic field experiences a greater force where the field lines are crowded. 2. Magnetic field lines of two magnets are shown in fig. A and fig. B. Select the figure that represents the correct pattern of field lines. Give reasons for your answer. Also name the poles of the magnets facing each other. Answer.  Figure B represents the correct pattern of field lines. In figure A, field lines cross each other which is not possible because if they cross each other, at the point of intersection, there would be two directions of field lines. In figure B, field lines are emerging in nature, so poles of magnet facing each ot...