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Name two ways that the electromagnetic force and gravitational force are different. Notes on Electric Potential Electric Field notes Imagine we have the Earth and a large asteroid as shown below. What will happen to the asteroid? Why? Notes on Electric Potential Electric Field notes Imagine we have the Earth and a large asteroid as shown below. What will happen to the asteroid? Why? It will be drawn toward the Earth and impact it from Earth’s gravitational field. Notes on Electric Potential Electric Field Now imagine we have the charges shown below. 1C -1,000 C What will happen to the + charge? Why? Notes on Electric Potential Electric Field Now imagine we have the charges shown below. 1C -1,000 C What will happen to the + charge? Why? It will get pulled to the negative charge because of their electric field. Notes on Electric Potential Field Lines So how do we draw this? The type of charge matters, so we need some way of showing direction and strength. We do this with field lines. Notes on Electric Potential Field Lines So how do we draw this? The type of charge matters, so we need some way of showing direction and strength. We do this with field lines. Scientists decided a long time ago that lines should go out from positive and in to negative. The vectors always point in the direction of the force that would act on a small positive test charge placed in the field Notes on Electric Potential Field Lines There are 3 things we need to know about field lines: 1) + charges move in the direction of the arrow, - charges move backwards. 2) The more closely packed the arrows are, the stronger the electric field is. 3) Unlike gravity, electric field lines can be blocked. Notes on Electric Potential Electric Shielding Metal and conductors shield or change our field lines. This is because electrons in metal can move very easily. Since they can move very easily, they try to spread out into the best configuration possible. Notes on Electric Potential Electric Shielding Metal and conductors shield or change our field lines. This is because electrons in metal can move very easily. Since they can move very easily, they try to spread out into the best configuration possible. Example: a charged, hollow sphere – – – – – – – – – – + – – – – – – – – – The charge spreads evenly, no matter where we place the charge inside! Notes on Electric Potential Electric Shielding Example: a charged, hollow cube –– – – – – – – + – – –– – –– – – – – – – The charge spreads out to get close to the positive, bu away from other negatives. This causes more to cluster on corners. Notes on Electric Potential Electric Shielding Example: a charged, hollow cube –– – – – – – – + – – –– – –– – – – – – – The charge spreads out to get close to the positive, bu away from other negatives. This causes more to cluster on corners. Faraday Cage If we put charges inside a box like this, we can tell how intense the charge is, but not where it's located since it evens out. Places like the FBI make use of this a lot. Notes on Electric Potential Electric Potential Just like how we have gravitational potential energy, we can have electric potential energy. Think of it like gravity. Positive charge wants to flow “downhill”. Negative charge wants to flow “uphill”. Notes on Electric Potential Electric Potential Assuming same charges, the farther we get from a charge, the less potential we have. We can draw lines of equipotential around charges. These are like elevation on a map. Charges can move on an equipotential line without using energy! e-field lines High potential equipotential Low potential circles Notes on Electric Potential Electric Potential move charges around Electric Potential formula Notes on Electric Potential Electric Potential move charges around Electric Potential formula Equations Change in = voltage work done ___________ charge Work (J) Charge (C) Voltage (V) equations Equations Electric Field Strength V or m vocab Vocabulary Electric Field The field created by charges that affects all other charges nearby. Field Lines A way of showing what the electric field looks like around a charge. Conductor An object that has free-flowing electrons. These can also shield electrical fields. Equipotential Places or curves in an electric field that have the same electric potential energy. Electric Potential The energy a charge can gain or lose by flowing “uphill” or “downhill” along field lines. Volt How much energy can be loaded on each Coulomb of charge. Exit Question #6 Which way do electric field lines and potential lines run? a) b) c) d) e) f) Both go from + to Both go around a charge Potential goes from + to -, field lines go around a charge Potential goes from - to +, field lines go around a charge Field lines go from + to -, potential go around a charge Field lines go from - to +, potential go around a charge