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| Questão | Responda |
| What is the law of reflection? The angle of incidence equals the angle of reflection The angle of incidence is less than the angle of reflection The angle of incidence is more than the angle of reflection | The law of reflection states that the angle of incidence equals the angle of reflection. |
| How do we describe the image in a plane mirror? Virtual and upright Virtual and upside down Virtual only | The image in a plane mirror is virtual and upright. It is virtual because it cannot be touched. When you next look in a mirror you are upright not upside down. |
| When does total internal reflection occur? When the angle of incidence equals the critical angle When the angle of incidence is less than the critical angle When the angle of incidence is beyond the critical angle | Total internal reflection occurs when the angle of incidence is beyond the critical angle. |
| How do we calculate the critical angle? sin c = 1 ÷ n sin c = 1 × n sin n = 1 × c | We calculate the critical angle using this equation sin c = 1 ÷ n. N is the refractive index. |
| Where do we use total internal reflection? For wireless signals Inside optical fibres Inside analogue cables | We use total internal reflection to send pulse of light along optical fibres. |
| Which of these is untrue about ray diagrams? The arrowheads show the direction of the light Lines must always be straight More arrowheads on lines means a brighter light | In ray diagrams you should only use one arrowhead. So more arrow heads meaning a brighter light is false. |
| What is the term that describes the changing direction of light when it changes medium? Reflection Dispersion Refraction | Refraction is the term that describes the changing direction of light when it changes medium. This occurs when light moves from air to glass. |
| Which statement explains why refraction occurs? Light rays curve Light rays change speed Light rays change direction | Refraction occurs when light rays change speed as they enter a medium with a different density. |
| Which of these is an advantage of using optical fibres? Fibres are rigid and do not bend Light is lost as it travels along the fibre Light travels very quickly | The fact that light travels very quickly along optical fibres is an advantage. |
| Where are optical fibres often used? By doctors in hospitals By teachers in schools By lawyers in court | Optical fibres are often used by doctors in hospitals to see inside their patients. This is called an endoscope. |
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