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Name: _________________________________ Date: _________________________ SNC1D CURRENT, VOLTAGE, RESISTANCE Current - - The _____________________ is the movement of the electrons It measures the amount of charge that passes a single point in a wire in every second An _________________________ is a device that is used to measure the amount of electric current flowing through a wire—it needs to be connected __________________ the circuit to be able to measure the current The unit of current is _____________________ (A) Voltage - - - The __________________ (V) measures two things: 1) the electrical potential energy 2) the electrical potential difference _________________________________: the energy that is given to the electrons in the battery (or other source)—this is the energy that is stored As electrons move through the circuit, they will give/lose some energy to the load—the amount of energy that the electrons give to the load is called the ________________________________________ A __________________ is a device that measures the electric potential difference at different parts of the circuit—a voltmeter needs to be connected OUTSIDE of the circuit in order to measure the voltages The unit of voltage is volts (V) Resistance - - Resistance is the ability of a material to slow down the flow of electric current The unit of resistance is the ______________ (Ω) and the device that measures resistance is called an ohmmeter—the ohmmeter also has to be connected on the ___________________ of the circuit. A multimeter is a device that can measure current, voltage and resistance by changing the settings on the machine A _____________________ is a device especially designed to reduce the flow of the current 1 Name: _________________________________ Date: _________________________ SNC1D Factors that Affect Resistance - - All materials have some internal resistance The bigger the resistance, the lower the current and the slower the electrons move. As the electrons move through the circuit, they bump into the atoms of the materials. This causes heat to be released. So the higher the resistance, the more the electrons are bumping into the material and the more it heats up. Internal resistance depends on a few factors: 1. Type of Material o Some materials allow electrons to move more freely than others o Copper is an excellent conductor and has low resistance o ____________________ is even better than copper but is more expensive 2. Cross-Sectional Area o The diameter of the cross-section gives you an idea how thick the wire is o The __________________ the diameter of the cross-section, the less resistance there is—this is because, in wider wires the electrons have more room to move freely 3. Length o When the wire is longer, the electrons have a greater distance to travel and so the resistance ____________________. 4. Temperature o When the wire is warmer, the wire gains energy and starts to vibrate. o As the wire vibrates, the electrons in the current are more likely to bump into the atoms of the wire—so as the temperature increases, the resistance increases 2