Calcular el tiempo necesario en ms. para ofectuar una variación de \( 2 \times 10^{-4} \mathrm{~Wb} \) en el flujo magnético, al desplazarse una bobina de 381 vueltas entre un campo magnético, el cual genera una fem media inducida de 17 V . Coloque tres decimales.

QUESTION 7 (Start on a new page.) 7.1 Reflection of light (and other forms of electromagnetic radiation) occurs when the waves meet a surface or other boundary that does not absorb the energy of the radiation and reflects the waves off the surface. Draw a fully labelled ray diagram to illustrate reflection.

8.4 To produce an emf of 9 V , the area of the coil, with its axis coinciding with the direction of a magnetic field (area perpendicular to magnetic field), is halved in 2 minutes from \( 0.6 \mathrm{~m}^{2} \) to \( 0,3 \mathrm{~m}^{2} \). Calculate the number of turns around the coil.

A coil with an area of \( 0.6 \mathrm{~m}^{2} \) is held with its axis coinciding with the direction of a magnetic field (surface perpendicular to magnetic field), with a strength of 0.4 T . 8.3 Calculate the magnetic flux.

9. Si dejamos caer al suelo una piedra cuya masa es de 4 kg desde una altura de 4 m , ¿Cuál es la energía cinética cuando ya ha recorrido la mitad de la caída a) hacia el suelo? b) CCual es la velocidad cuando alcanza el suelo?

7.2 A beam of light travels from water to plastic. The speed of light in plastic is \( 2,05 \times 10^{8} \mathrm{~m} \cdot \mathrm{~s}^{-1} \). The refractive index of water is 1,33 . Calculate the refractive index of plastic.