| what is kirchoffs first law? | charge flowing into a circuit junction must equal the sum of charge leaving the junction |
| what is kirchoffs second law? | within any closed loop the sum of the emfs is equal to the sum of the products of current and resistance |
| what happens when pd is applied across a conducter? | the electrons accelerate and gain kinetic energy |
| what is ohms law? | current flowing within a conductor is directly proportional to the pd across it provided that physical conditions such as temperature remain constant |
| what factors affect resistance ? | cross sectional area , material, length and temperature |
| how does cross sectional area of a wire affect its resistance? | a thicker wire means lower resistance as there is a bigger volume of space for the electrons to flow in |
| how does the material of a wire affect its resistance? | metals have delocalised electrons making them good conductors so resistance is lower . plastics and insulators do not so they have a higher resistance |
| how does the length of a wire affect its resistance? | as the length of the wire increases so does the electrical resistance as electrons experience a smaller pd gradient as wire gets longer. the size of voltage per metre value decreases causing a lower drift velocity and more ions for electrons to collide with |
| how does temperature affect its resistance | as tempt increases it causes ions to gain kinetic energy and move faster making it more difficult to pass without collisions resulting in more resistance |
| explain the current in series circuits | current is the same |
| explain the current in parallel circuits | current splits into each branch and add to make the total current |
| explain the potential difference in series circuits | pd splits in ratios according to resistance |
| explain the potential difference in parallel circuits | voltage in each branch is the same |
| what happens when you add resistors in parallell? | the total resistance decreaces |
| how do you find total emf if there are two emf in series | add them |
| how do you find total emf if there are two emf in parallel | subtract them |
