812249
Description
Flashcards by Chloe Roberts, updated more than 1 year ago
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Created by Chloe Roberts
about 10 years ago
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| Question | Answer |
| What is the national grid? | A network of cables and transformers used to distribute electricity |
| What are step-up transformers? | They increase the voltage and lower the current, so less heat is lost making the system more efficient |
| What are step-down transformers? | They decrease the voltage , so it is more safe to use in buildings. |
| What are 4 disadvantages of underground cables? | Expensive ⟶ difficult to install ⟶ difficult to repair ⟶ closer to humans |
| What do waves transfer? | Energy and information |
| What are transverse waves? | Transverse waves vibrate perpendicular to direction of energy transfer. All electromagnetic waves are transverse |
| What are longitudinal waves? | Longitudinal waves vibrate parallel to direction of energy transfer. Sound waves are longitudinal |
| What is the amplitude? | The Height of the waves from the middle (rest) to the top (peak) |
| What is the frequency (Hertz,HZ) | The number of waves passing in one second |
| What is the Wavelength? | The distance from one wave peak to the next |
| What is a plain mirror? | A flat mirror |
| What is the normal? | A dashed line drawn perpendicular to the mirror |
| What is a Virtual image? | It is a image formed from virtual rays and CANNOT be projected onto a screen |
| What is the angle of incidence? | The angle of reflection |
| How do you draw reflection in 3 steps? | 1. Draw the image same distance from the mirror ⟶ 2. Draw straight lines (virtual and real) from image to eye ⟶ 3. Draw reflected rays the to object |
| What is refraction? | When waves change direction (bend) as they cross a boundary |
| Why does refraction happen? | Because the waves change speed in each substance |
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