12628066
Description
Flashcards by Eagan Morrell, updated more than 1 year ago
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Created by Eagan Morrell
over 6 years ago
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| Question | Answer |
| What is conventional current flow? | Positive to negative charge |
| What is the formula to work out resistance in series? | RT = R1+R2...+RN |
| The unit of charge | q, the coloumb |
| Properties of current | Unit: I The number of electrons per second carried through a conductor |
| Properties for voltage | Unit: V The potential difference between negatively charged and positively charged objects |
| Properties of resistance | Unit: R Property of material that helps prevent the flow of electrons in it. |
| What is static electricity? | Static electricity occurs when there is a build up of electric charge on the surface of a material. |
| Why is static electricity so called? | Static electricity is so called because the charges don't move. The electricity we use everyday involves moving charges. |
| How is static electricity caused? | Static electricity is caused when certain materials are rubbed against each other and electrons are stripped off. |
| What do electrons have to do with static electricity? | Electrons are stripped off one material and onto another. |
| Materials with extra electrons... | ...are negatively charged. |
| Materials that have lost electrons... | ...become positively charged. |
| What are the 2 types of current (acronyms and names)? | DC - Direct Current AC - Alternating Current |
| Where is AC current commonly found? | In power sockets in the wall. |
| Give one example (probably the main example) of where direct current is used | Main example: Batteries |
| Alternating current | Flow of charge back and forth, changing its direction many times in a second (50-60 Hz) |
| Direct Current | Flow of charge always in one direction |
| 1 Hertz (Hz) | 1 Hertz (Hz) = 1 cycle per second |
| The Central Concept | Closed circuits |
| Ohm's Law states that: | Ohm's Law states that electric current flowing through a wire is directly proportional to the potential difference across its ends, provided its temperature remains the same. |
| What does 'directly proportional' mean? | Directly proportional means if one variable is always the product of the other variable and a constant. eg) Voltage (V) is variable 1 Current (I) is variable 2 Resistance (R) is a constant (K) Variable 1 = Variable 2 x constant Voltage = Current x Resistance V = IR Hence Ohm's Law |
| In a parallel circuit, current is... | ...split |
| In a series circuit, voltage is... | ...split |
| In a series circuit, current... | ...remains the same |
| In a parallel circuit, voltage... | ...remains the same |
| Another equation for current is: | I = Q/t (total charge per second) |
| In the equation I = Q/t, what does each variable mean? | I = Current Q = Total charge t = time |
| Another formula for voltage is: | V = w/q (joules per charge) |
| In the equation V = w/q, what does each variable mean? | V = Voltage w = work done, energy, joules q = charge |
| List as many formulas for POWER as you can: | More common formula: P = w/t, or work done divided by time (seconds) Also known as joules per second. Other formulas for Power: P = VI (watts) P = w/t (watts) P = V squared / R P = R x I squared P = F.d/t (work done/energy) or P = F x V |
| What does Kirchhoff's 1st Law state? | The sum of total current equals to 0 eg) I (in) = I1+I2+I3...+IN |
| What does Kirchhoff's 2nd Law state? | The sum of total voltage equals 0. eg) V (in) = V1+V2+V3...+VN Each path in a parallel circuit is one loop for voltage. eg) There are 4 paths in a parallel circuit. The voltage in each path is 12 volts. One path is therefore 12 volts. With that being said, in series, voltage is split, so if there are 2 equal resistors in the now series path, the voltage will split up into 6 volts each. If the resistors are of different value, the voltage will vary, however, they will always add up to 12 volts at the end of the circuit. |
| Explain how VI = w/t using other known formulas | V = w/q I = Q/t therefore P = w/q x Q/t = w/t therefore VI = w/t OR V = w/q therefore w = Vq I = Q/t therefore t = Q/I So P = w/t = Vq x I/Q = VI therefore VI = w/t |
| Unit for energy: | Joules (J) |
| Unit for time: | Seconds (s) |
| Unit for power: | Watt (w) |
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