Electromagnetic waves from a radio station pass through an open window of a house. The square window has side length 0.75 m and the waves pass through perpendicular to the window's area. The electric field is measured at the window and found to be 0.02 V/m. In air, we can use the vacuum permeability = 4 x 10-7 H/m. (i) What is the magnitude of the Poynting vector, S, for the radio waves passing through the window? (ii) How much energy do the radio waves carry through the window during a 2-minute-long broadcast of BBC Radio 4's shipping forecast? [Hint: think of the units of S [units = (J/s)/m²] and Energy [units = J].

Electromagnetic waves from a radio station pass through an open window of a house. The square window has side length 0.75 m and the waves pass through perpendicular to the window's area. The electric field is measured at the window and found to be 0.02 V/m. In air, we can use the vacuum permeability = 4 x 10-7 H/m. (i) What is the magnitude of the Poynting vector, S, for the radio waves passing through the window? (ii) How much energy do the radio waves carry through the window during a 2-minute-long broadcast of BBC Radio 4's shipping forecast? [Hint: think of the units of S [units = (J/s)/m²] and Energy [units = J].