In a particular experiment, a radioactive samplehas its mass halved every 1.5 hours. After 6 hours from the start of the experiment, its mass is 300 grams, (i) Find the initial mass of the radioactive sample (ii) Calculate the mass of the radioactive sample. 24 hours after the start of the experiment. (iii) Yasir intends to end the experiment once the mass of the radioactive sample is 75 grams. Determine the duration of the experiment.

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.

What is the difference between construction and destruction interference?

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.

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.

How does reflection change a wave?