About 10% of the power of a 100W light bulb is converted to a visible radiation. What is the average intensity of visible radiation. at a distance of 1m from the bulb?

About 10% of the power of a 100W light bulb is converted to a visible radiation. What is the average intensity of visible radiation. at a distance of 10 m?

The blades of a windmill sweep out a circle of area A. (a) If the wind flows at a velocity v perpendicular to the circle, what is the mass of the air passing through it in time f?(b) What is the kinetic energy of the air? (c) Assume that the windmill converts 25% of the wind’s energy into electrical energy, and that A = 30 m^- 2 , v = 36 km/h and the density of air is 1.2 kg m^-3 . What is the electrical power produced?

The focal lenghts of objectives and eyepiece of a telescope are 200cm and 10 cm respectively. Is is used to get an image of the Sun on a screen placed 40cm behind the eyepiece. The diameter of the image is 6cm. What is the diameter of the Sun? Give the distance from earth to the Sun is 1.5xx10^(11)m .

Calculate the peak value of electric and magnetic field produced by a radiation coming from a 100 watt bulb at a distance 3 cm.

Light from a point source in air falls on a convex spherical glass surface ( refractive index = 1.5, radius of curvature = 20 cm). The distance of light source from the glass surface is 100 cm. At what position is the image formed ?

Joseph jogs from one end A to other end B of a straight 300 m road in 2 minutes 30 seconds and then turns around and jogs 100 m back to point C in another 1 minute. What are Joseph’s average speed and velocities in jogging (a) from A to B and (b) from A to C?