CIE iGCSE Co-Ordinated Science P3.2.2 Refraction of light Exam Style Questions Paper 3
Question
(a) Fig. 12.1 shows a block of glass with a ray of light passing through it. The ray of light is passing from the air into the glass.
(i) On Fig. 12.1, label the angle of incidence with the letter i and the angle of refraction with the letter r.
(ii) On Fig. 12.1, complete the diagram to show how the ray of light continues through the glass and out into the air.
▶️Answer/Explanation
(i) The angle of incidence (i) is the angle between the incident ray and the normal (a line perpendicular to the surface of the glass at the point of incidence). The angle of refraction (r) is the angle between the refracted ray and the normal. Both angles should be labeled on the diagram.
(ii) When the ray of light enters the glass, it bends towards the normal (since glass is denser than air). When it exits the glass, it bends away from the normal. The ray should continue in a straight line parallel to the original incident ray but displaced due to refraction.
(b) Fig. 12.2 shows rays of light from an object projected onto a screen through a thin converging lens.
(i) State the name of the distance M.
(ii) Circle two words or phrases that correctly describe the image on the screen.
diminished enlarged inverted same size upright
▶️Answer/Explanation
(i) The distance M is the focal length of the lens, which is the distance from the lens to the focal point where parallel rays of light converge.
(ii) The correct words to describe the image on the screen are enlarged and inverted. A converging lens can produce an enlarged and inverted image when the object is placed between the focal point and twice the focal length from the lens.
(c) A robot is used to collect samples of radioactive material from a nuclear storage facility.
(i) Explain why the robotic vehicle is more suitable to collect the radioactive material than a human being.
(ii) Fig. 12.3 is a graph of the radioactive decay curve for a sample of the radioactive material. Use the graph in Fig. 12.3 to determine the half-life of the sample.
▶️Answer/Explanation
(i) The robotic vehicle is more suitable for collecting radioactive material because it can operate in high-radiation environments without risking human health. Robots can be designed to handle hazardous materials safely, reducing the risk of exposure to harmful radiation.
(ii) The half-life of the radioactive material can be determined from the graph by finding the time it takes for the activity to decrease to half of its initial value. For example, if the initial activity is 1000 counts/s and it decreases to 500 counts/s after 2 years, the half-life is 2 years.
(d) The robot has a d.c. motor. State two ways in which the turning effect of the current-carrying coil in the magnetic field of a d.c. motor can be increased.
▶️Answer/Explanation
Two ways to increase the turning effect (torque) of the current-carrying coil in a d.c. motor are:
- Increase the current flowing through the coil, as the force on the coil is directly proportional to the current.
- Increase the strength of the magnetic field, either by using stronger magnets or by increasing the number of turns in the coil.