Which type of electromagnetic radiation can not be focused

If a tank filled with water contains a block and the height of the water above point a within the block is 0.8 meter, what is the pressure at point a?

Which atomic model was proposed as a result of j. j. thomson’s work?

Avery long solenoid of inner radius 2.75 cm creates an oscillating magnetic field of the form = for this solenoid, =0.00425 t and =319 rad/s. (a)what is the maximum value of the induced electric field at a perpendicular distance 1.45 cm from the axis of the solenoid? (b) what is the maximum value of the inducted electric field at a point 5.85 cm perpendicular from the axis of the solenoid?